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Belaribi, Chakib. "Etude rhéologique et thermique des mélanges binaires et ternaires. : Polycarbonates/Tetraméthyl/Polycarbonates, Polystyrène/Polycarbonates/Tétraméthyl Polycarbonate." Pau, 1985. http://www.theses.fr/1985PAUU1002.
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Propriétés rhéologiques et thermiques de ces mélanges amorphes à l'état fondu à l'aide de différentes techniques rhéologiques et physicochimiques. Dans chacun des cas, on essaye de corréler le comportement rhéologique à l'état fondu a la microstructure des mélanges, déterminée par analyse thermique et microscopie électronique.
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Le, Bail Nicolas. "Conception, synthèse par chimie douce et caractérisation de revêtements sol-gel hybrides multifonctionnels sur polycarbonate." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0040/document.
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Le polycarbonate (PC) est un matériau polymère très répandu, fort apprécié pour sa faible densité, sa transparence, ses bonnes propriétés mécaniques et surtout pour son faible coût. Même s’il présente quelques limites essentiellement liées à sa faible résistance à l’abrasion, à la rayure et à sa dégradation dans le temps (sous UV ou hydrolyse), le PC trouve sa place dans un large spectre d’applications (bâtiment, automobile, médical, optique…). Il reste à ce jour indispensable sur ce marché car aucun autre polymère ne présente d’aussi bonnes propriétés mécaniques à prix égal. C’est dans ce contexte que ces travaux de thèse ont permis de développer une solution permettant de protéger le PC de toute agression extérieure par le dépôt d’un revêtement protecteur. L’étude s’est orientée vers le dépôt d’un film hydride organique / inorganique à base de silice, préparé par voie sol-gel, ce procédé permettant une élaboration à une température compatible avec la température de transition vitreuse du PC (Tg) (148°C). Les solutions retenues pour obtenir un revêtement performant sont basées sur la synthèse de revêtements hybrides à base d’oxydes de silicium et de zirconium. Une attention particulière a été portée sur l’augmentation de l’adhérence du film au substrat d’une part, et l’optimisation du procédé (synthèse et traitement de densification), d’autre part. Les résultats sont présentés d’un point de vue physico-chimique (IR, XRR, RMN) et mécanique (nanoindentation, adhésion et test à la rayure)The polycarbonate is a widespread polymer material, highly appreciated for its low density, its transparency and its good mechanical properties. This material is used for divert applications (automotive, medical, optical...) and is very competitive in terms of quality and prices. However, it displays some weaknesses, essentially due to its poor abrasion and scratch resistance and its possible degradation under UV or hydrolysis. In this context, the PhD aim is to design and develop a new hybrid organic / inorganic protective coating with silica and zirconia based precursors prepared by the sol gel process, which allow a curing compatible with the polycarbonate's Tg (148°C). Here, it is discussed on the solutions retained to obtain a scratch resistant, hydrophobic and transparent coating. It is showed that, scratch resistant protective coatings can be deposited on pristine PC thanks to a performing hybrid organic / inorganic coating by modulating its bulk properties. Moreover, results demonstrate the key role played by a phenylsilane precursor in enhancing the adherence. Nanoindentation, scratch-test, NMR and FTIR analysis will be discussed
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Dreistadt, Cynthia. "Analyse expérimentale et modélisation micromécanique du comportement du polycarbonate soumis aux chargements complexes." Thesis, Metz, 2007. http://www.theses.fr/2007METZ049S/document.
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Le comportement des polymères amorphes suscite un intérêt certain dans le monde de la recherche car leurs domaines d'application sont très varies. La transparence et une grande rigidité sont de grands atouts qui font du polycarbonate (pc) un des polymères techniques les plus usités. Les lois phénoménologiques ne permettent pas de reproduire correctement le comportement de ce polymère. Cette étude se propose donc d'étudier le comportement du pc a partir d'essais simples et complexes de compression uniaxiale en quasi statique et à température ambiante. Des essais comprenant plusieurs cycles de charge – décharge – maintien a effort constant sont réalisés avec différents niveaux et temps de maintien. Une autre série d’essais est destinée a mettre en évidence l’anisotropie induite du pc. L’ensemble de ces essais est ensuite comparé au modèle de boyce, parks et argon (1988) très référencé dans la littérature afin de tester sa validité. Certaines lacunes de cette approche sont ainsi mises en évidence. Finalement, un nouveau modèle micromécanique est proposé, basé sur la structure du polymère et l'évolution de celle-ci et inspire des modèles de plasticité pour les métaux. La notion de pelote comprenant plusieurs chaînes moléculaires est introduite. La déformation totale est décomposée de façon additionnelle en parties élastique, anélastique et plastique. L’écrouissage est naturellement introduit grâce à la combinaison de la notion de pelote et du modèle de lin (1957). Une première validation de ce modèle est proposée, fournissant des résultats particulièrement encourageants pour les travaux futursThe behaviour of amorphous polymers is of a great interest in the research world because their application fields are various.transparency and high stiffness are the major advantages which made polycarbonate (pc) one of the most machined technical polymers. Phenomenological laws don’t allow reproducing correctly the behaviour of this polymer. this study proposes to analyze the pc’s behaviour based on simple and complex uniaxial compressive tests, in quasi static conditions and at room temperature. Tests with different loading – unloading – maintaining at constant forces cycles are done with various levels and maintaining times. Another series of tests is dedicated to show the induced anisotropy of pcs. all these experiments are compared to the boyce, parks and argon’s model (1988) very represented in the literature in order to check its validity. some lacks of this approach are enlightened. finally, a new micromechanical model is proposed based on the polymer structure and on its evolution, and inspired from metal plasticity models. the concept of balls which include several molecular chains is introduced. the total strain is additionally decomposed of three parts: elasticity, anelasticity and plasticity. The hardening is naturally introduced thanks to the combination of ball concept and lin’s model (1957). A first validation of this model is proposed, giving encouraging results for further works
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AKELE, NGONGO. "Vieillissement hydrolytique du polycarbonate." Paris, ENSAM, 1995. http://www.theses.fr/1995ENAM0014.
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Le vieillissement hydrolytique du polycarbonate de bisphenol-a (pc) a ete etudie dans l'intervalle 70-100c, par mesure des masses moleculaires, gravimetrie et analyse enthalpique differentielle. Pour les echantillons etudies (epaisseur 2 mm), la cinetique d'hydrolyse n'est pas gouvernee par la diffusion. Cette derniere n'est pas affectee par le vieillissement physique. L'hydrolyse se traduit par une augmentation de l'hydrophilie liee a l'accumulation d'especes tres polaires (phenols et acides). On observe une perte de masse environ quatre fois superieure a ce que l'on attendait dans le cas d'un processus de coupure de chaine statistique accompagne d'une decarboxylation de l'acide. Cette perte de masse est essentiellement due a la formation de bisphenol-a (qui cristallise) et d'oligomeres. Pour expliquer un rendement aussi eleve en monomere, nous avons teste un certain nombre d'hypotheses dont la plus realiste est la suivante: l'hydrolyse est un processus equilibre. La reaction inverse (recombinaison) est favorisee car les extremites de chaines sont peu mobiles dans le polymere a l'etat vitreux. Cependant, lorsque l'hydrolyse se produit au voisinage d'une extremite de chaine, la diffusion du fragment court ainsi forme est favorisee et la vitesse apparente d'hydrolyse s'en trouve augmentee. Ce mecanisme a l'avantage de rendre eventuellement compte de l'effet accelerateur de contraintes de traction sur l'hydrolyse. Cette interpretation est confortee par l'etude comparative des modeles cycliques (effet de la tension) et non cycliques
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Robertson, Jennifer E. "Thermal Degradation Studies of Polycarbonate." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27704.
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Polymeric materials are increasingly being used in diverse, very demanding applications. Either pre- or post- application environments may require exposures to conditions hostile to the polymer's integrity. Frequently, these demanding conditions result in degradation of the polymer and subsequent decreases in desirable properties. Clearly then, a methodology to predict important properties, such as Tg, molecular weight, and tensile strength, from knowledge of the environmental history of a polymeric-based specimen is beneficial.
The current study focuses on bisphenol A polycarbonate and tracks changes in the properties of this material as a function of the degree of degradation, t. For the purposes of the present research, the environmental effects have been limited to those associated with elevated temperature, although the methodology is general. This t parameter is a product of the kinetic rate constant, k, found from isothermal kinetics, and the time of degradation, t. Elucidation of t has been linked to measurement of the molecular weight distribution which in turn can be related to various properties to yield predictive relationships for these properties. Only the thermal history of the polymer and its initial properties are required for the model. This technique is not limited to a specific polymer or even to thermal degradation. As long as the kinetics of the process can be mathematically modeled, this approach should apply to a host of other situations, providing property prediction simply from knowledge of the material history.
The research seeks to better understand the thermal degradation of polycarbonate. Kinetics of the process was explored, and the chemical mechanisms were examined. A key part of the project was the determination of the molecular weights and molecular weight distributions at each level of degradation. Furthermore, mechanical stress-strain properties, glass transition temperatures, and melt viscosities were also measured. This information, together with the kinetic expressions, facilitated prediction of these types of material properties for a known thermal history.Ph. D.
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Hokenek, Selma. "Characterization of Conductive Polycarbonate Films." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/2016.
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Transparency and conductivity are highly desirable qualities in materials for modern gas sensors. Polymer gas sensors have been developed in which the polymer acts as a solid electrolyte. However, these types of sensors are opaque, which limits their potential for integration with dichromatic materials. The development of a sensor integrating conductive polymer films and dichromatic materials requires the implementation of a transparent conductive polymer film. The potential of iodine-doped bisphenol-a polycarbonate films containing bis(ethylenedioxy)-tetrathiafulvalene (BEDO-TTF) dye for sensor applications will be tested through characterization of the films at various stages of their fabrication using Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), transmission Fourier Transform Infrared Spectroscopy (FTIR), Optical Microscopy (OM), and Four Point Probe conductivity measurements (FPP). FTIR results show that there is an interaction between the polycarbonate matrix and the dye-iodine complex. Measured resistivities of the iodine doped films range from 148 Omega-cm to 2.82 kOmega-cm depending on the concentration of the iodine and exposure time. The imaging techniques used show a significant difference in the structure and the surface of the iodine doped-PC-BEDO-TTF films with respect to the bare polycarbonate films or the films mixed with the organic dye. It is also clear that the surface roughness of the prepared conductive films increases with iodine loading. These films have the potential to be used in sensor or photovoltaic applications.
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Dubromez, Vincent. "Amélioration des performances du polycarbonate et des mélanges polycarbonate/polystyrène par des copolymères à blocs ABC." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10139.
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Le polycarbonate (PC) est un polymère thermoplastique particulièrement intéressant pour de nombreuses applications industrielles et biomédicales, de par ses propriétés d’usage exceptionnelles (transparence, résistance mécanique et thermique). Néanmoins, il présente deux défauts majeurs : sa viscosité élevée et sa sensibilité à l’entaille. L’objectif de cette étude est de remédier à ces inconvénients, tout en préservant sa transparence. Pour ce faire, trois voies ont été envisagées : (i) amélioration de la fluidité par ajout de polystyrène (PS), (ii) renforcement par des copolymères à blocs de type poly(styrène-b-butadiène-b-méthacrylate de méthyle) (SBM) et (iii) utilisation simultanée de PS et de SBM. L’incorporation du PS permet de fluidifier le PC, tout en conservant sa transparence. Toutefois, les propriétés mécaniques des mélanges PC/PS sont inférieures à celles du PC seul. L’étude des mélanges binaires PC/SBM montre que la nature et la fraction de copolymère SBM incorporé, ainsi que la viscosité de la matrice, jouent un rôle déterminant sur les propriétés finales. L’étude des mélanges ternaires PC/PS/SBM démontre qu’il est possible d’obtenir une amélioration des propriétés au choc, toute en préservant la transparence du PC, à condition de générer une morphologie homogène et bien dispersée. Ceci implique une combinaison optimale entre la fluidité de la matrice PC, la nature et la fraction de copolymères à blocs et du PS dans le mélange, et un choix judicieux des paramètres technologiques de mise en œuvrePolycarbonate (PC) is a widely used thermoplastic polymer for numerous industrial and biomedical applications, due to its exceptional use properties (transparency, mechanical and thermal behavior). Nevertheless, the PC exhibits two major defects: high viscosity and poor notch impact properties. The goal of the present study was to propose a solution for these two issues, while preserving the PC transparency. Three ways were investigated: (i) the decrease of viscosity via adding polystyrene (PS), (ii) the improvement of notch impact behavior by adding poly(styrene-b-butadiene-bmethylmethacrylate) block copolymers (SBM) and (iii) simultaneous use of PS and SBM. Adding PS to a PC matrix does decrease its viscosity, while preserving the transparency. However, the mechanical properties of PC/PS blends are inferior to those of the neat PC. The experimental study on binary PC/SBM blends point out the great influence of the nature and proportion of the copolymer in the blend, as well as of the matrix viscosity, on the final properties of the blends. The investigation of the ternary PC/PS/SBM blends demonstrate that it is possible to obtain an improvement of the notch impact properties, while preserving the PC transparency – by generating a homogeneous and well dispersed blend morphology. This requires an optimal combination between the matrix fluidity, the nature and the proportion of block copolymers and PS, and also an appropriate choice of the processing conditions
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Guérin, William. "Préparation catalytique de nouveaux matériaux polyesters et polycarbonate." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S069.
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Les polyesters et polycarbonates aliphatiques biocompatibles et biodégradables sont typiquement utilisés pour la fabrication de matériaux médicaux tels que les fils de sutures ou les capsules de libération contrôlée de principe actif. Ces polymères synthétiques sont aussi développés comme substituts aux plastiques issus du pétrole. La méthode de choix pour obtenir des polycarbonates ou polyesters de longueur et de structure contrôlée est la polymérisation par ouverture de cycle (ROP) de monomères cycliques à cinq ou six chaînons. Actuellement, la majorité de ces polymères présentent des propriétés physiques intéressantes mais souvent limitées à certaines applications spécifiques. Des efforts sont donc consacrés à la synthèse de nouveaux monomères et polymères ou copolymères avec des microstructures contrôlées afin de moduler à convenance les propriétés thermiques et mécaniques du matériau final. Tandis que le poly(triméthylène carbonate), PTMC, est un élastomère, le poly(L-lactide), PLLA, est un polyester fragile. L’association de ces monomères au sein d’un copolymère a permis d’améliorer et de moduler les propriétés thermo-mécaniques du PLLA. Selon la nature de la copolymérisation (séquentielle ou simultanée) et du système catalytique utilisé, des copolymères de microstructures différentes ont été obtenus. Cette approche a permis de synthétiser de nouveaux polycarbonates ou poly(carbonate-co-ester) bien définis, notamment à partir de carbonates cycliques à cinq chaînons, comme le carbonate d’éthylène ou le carbonate de cyclohexène, réputés non polymérisable. Il devient alors envisageable de préparer de nouveaux polymères jusqu’alors supposés non synthétisable et ainsi d’accéder à de nouveaux matériaux biodégradable susceptibles de pouvoir remplacer les polymères de commodités problématiques comme le polycarbonate de bisphénol ABiocompatible and biodegradable aliphatic polyesters and polycarbonates are typically used for the manufacture of medical devices such as sutures or capsules for controlled release of active molecules. These synthetic polymers are also developed as substitutes for petroleum-based plastics. The method of choice for the synthesis of polycarbonates or polyesters with controlled length and structure is the ring-opening polymerization (ROP) of five or six membered ring cyclic monomers. Currently, the majority of these polymers exhibit interesting physical properties but often limited to specific applications. Efforts are therefore devoted to the synthesis of new monomers and polymers or copolymers with controlled microstructure to modulate at convenience the thermal and mechanical properties of the final material. Whereas poly(trimethylene carbonate), PTMC, is an elastomer, poly(L-lactide), PLLA, is a fragile polyester. The combination of these monomers in a copolymer has improved and modulate the thermo-mechanical properties of PLLA. Depending on the nature of the copolymerization (sequential or simultaneous) and the catalytic system used, copolymers of different microstructures were obtained. This approach has allowed to synthesize new well defined polycarbonates or poly(carbonate-co-ester), especially from five-membered cyclic carbonates such as ethylene carbonate or cyclohexene carbonate, known for being not polymerizable. It then becomes possible to prepare new polymers supposed to be not synthesizable and access to new biodegradable materials that can replace problematic commodity polymers such as bisphenol A polycarbonate
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Clay, Stephen Brett. "Characterization of Crazing Properties of Polycarbonate." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28648.
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The purpose of this study was to characterize the craze growth behavior of polycarbonate (PC) as a function of stress level, model the residual mechanical properties of PC at various craze levels and strain rates, and determine if the total surface area of crazing is the sole factor in residual properties or if the crazing stress plays a role. To obtain these goals, a new in-situ reflective imaging technique was developed to quantify the craze severity in transparent polymers.
To accomplish the goal of craze growth rate characterization, polycarbonate samples were placed under a creep load in a constant temperature, constant humidity environment. Using the new technique, the relative craze density was measured as a function of time under load at stresses of 40, 45, and 50 MPa. The craze growth rates were found to increase exponentially with stress level, and the times to 1% relative craze density were found to decrease exponentially with stress level. One exception to this behavior was found at a crazing stress of 50 MPa at which over half of the samples tested experienced delayed necking, indicating competitive mechanisms of crazing and shear yielding. The draw stress was found to be a lower bound below which delayed necking will not occur in a reasonable time frame.
The yield stress, elastic modulus, failure stress, and ductility were correlated to crazing stress, relative craze density, and strain rate using a Design of Experiments (DOE) approach. The yield stress was found to correlate only to the strain rate, appearing to be unaffected by the presence of crazes. No correlation was found between the elastic modulus and the experimental factors. The failure stress was found to decrease with an increase in relative craze density from 0 to 1%, increase with an increase in crazing stress from 40 to 45 MPa, and correlate to the interaction between the crazing stress and the strain rate. The ductility of polycarbonate was found to decrease significantly with an increase in relative craze density, a decrease in crazing stress, and an increase in strain rate.
The craze microstructure was correlated to the magnitude of stress during craze formation. The area of a typical craze formed at 40 MPa was measured to be more than 2.5 times larger than the area of a typical craze formed at 45 MPa. The fewer, but larger, crazes formed at the lower stress level were found to decrease the failure strength and ductility of polycarbonate more severely than the large number of smaller crazes formed at the higher stress level.Ph. D.
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Berlich, Robert. "Alterung und Rissbildung unter Medieneinfluss bei Polycarbonat = Aging and crack initiation under the influence of liquid medium at polycarbonat /." Aachen : Mainz, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014188220&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Cloarec, Thomas. "Processing and Characterization of Polycarbonate Foams with Supercritical Co2 and 5-Phenyl-1H-tetrazole." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc799500/.
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Since their discovery in the 1930s, polymeric foams have been widely used in the industry for a variety of applications such as acoustical and thermal insulation, filters, absorbents etc. The reason for this ascending trend can be attributed to factors such as cost, ease of processing and a high strength to weight ratio compared to non-foamed polymers. The purpose of this project was to develop an “indestructible” material made of polycarbonate (PC) for industrial applications. Due to the high price of polycarbonate, two foaming methods were investigated to reduce the amount of material used. Samples were foamed physically in supercritical CO2 or chemically with 5-phenyl-1H-tetrazole. After thermal characterization of the foams in differential scanning calorimetry (DSC), we saw that none of the foaming methods had an influence on the glass transition of polycarbonate. Micrographs taken in scanning electron microscopy (SEM) showed that foams obtained in physical and chemical foaming had different structures. Indeed, samples foamed in supercritical CO2 exhibited a microcellular opened-cell structure with a high cell density and a homogeneous cell distribution. On the other hand, samples foamed with 5-phenyl-1H-tetrazole had a macrocellular closed-cell structure with a much smaller cell density and a random cell distribution. Compression testing showed that polycarbonate foamed physically had a compression modulus a lot greater. Then, XLPE mesh 35 or 50 and wollastonite were added to the polymeric matrices to enhance the foaming process and the mechanical properties. DSC experiments showed that the addition of fillers changed the thermal properties of polycarbonate for both foaming methods by inducing a shift in glass transition. SEM revealed that fillers lowered the average cell diameter and increased the cell density. This phenomenon increased the compression modulus for polycarbonate foamed in supercritical CO2. However, mechanical properties decreased for samples foamed with 5-phenyl-1H-tetrazole due to their relative brittleness and the propagation of microcracks.
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Abdallah, Jassem. "Polycarbonate-silsesquioxane and polycarbonate-siloxane nanocomposites: synthesis, characterization, and application in the fabrication of porous inorganic films." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37271.
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Three types of poly(norbornane carbonate) or PNC oligomers were synthesized and characterized via spectroscopic methods and elemental analyses to validate their chemical structures. Using the results from proton nuclear magnetic resonance (1H NMR) experiments, the degree of polymerization and size of each PNC chain was estimated via end-group analysis. All three types of PNC structures were both thermally-labile and acidolytically-labile, allowing them to be used as sacrificial materials in both direct-write and thermally-processed template systems. Thermogravimetric analysis (TGA) data was used to determine the kinetic parameters for the thermolytic decomposition reactions and evolved-gas analysis via mass spectrometry (TGA-MS) was used to determine the mechanisms for thermolytic degradation.
PNC oligomers were freely-mixed with hydrogen silsesquioxane (HSQ) to form solutions that were spin-coated to form templated films. Transmission electron microscopy (TEM) showed that the free-mixing of PNCs with HSQ resulted in the agglomeration of the porogen molecules during the spincoating step. This phase-segregation produced domain sizes much larger than those of the individual chains, and during decomposition large pores were produced. To combat the phase segregation, hydrosilylation reactions were used to covalently bond vinyl end-capped PNC chains to silane-functionalized siloxane and silsesquioxane molecules. These matrix-like materials served as compatibilizers in order to improve the phase-compatibility of the sacrificial polymers in HSQ films. NMR and GPC analyses showed that the solids recovered from the hydrosilylation reactions were binary mixtures of hybrid nanocomposite molecules and residual ungrafted PNC chains.
TEM imaging showed that the domains in these nanocomposite films had bimodal size distributions due to the presence of two components in the mixtures. The hybrid molecules produced pores ranging in size from about 6-13 nm as a result of improvements in the phase-compatibility of the grafted oligomers. However, the residual ungrafted oligomers in the blends produced larger domains measuring 30-40 nm. It is believed that separation difficulties can be avoided if the vinyl termination reaction conditions can be adjusted to ensure 100% conversion of all the terminal hydroxyl groups to vinyl groups. Doing so would allow all PNC chains to be grafted during hydrosilylation reaction; thus, avoiding the recovery of free PNC oligomers.
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Johnson, Michael DeShawn 1977. "Deformation and fracture of polycarbonate and rubber-modified polycarbonate under controlled temperature, deformation rate, and notch stress triaxiality." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8544.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (leaves 217-220).
The deformation and fracture of polycarbonate and polycarbonate toughened with methyl-methacrylate shell/polybutadiene core sub-micron particles are investigated. The effects of strain rate, temperature, and notch stress triaxiality on deformation and fracture are studied. The Arruda-Boyce constitutive model for glassy polymers and finite element simulations are used to simulate the deformation of the polycarbonate homopolymer subjected to compression and tension under un-notched and notched conditions. Compression of polycarbonate in uniaxial compression is found to exhibit an initially elastic response followed by yield, then strain softening and strain hardening at large strains. The yield stress is found to be dependent on temperature and strain rate. Yield stress is shown to increase with increasing strain rate and decrease with increasing temperature. Load-displacement behavior of un-notched polycarbonate is shown to exhibit an initially elastic response followed by macroscopic yield, then a load drop, and then a load plateau as the neck stably propagates, soon after the neck has propagated the full length of the specimen it begins to travel into the grip region, ductile failure occurs due to extensive stretching. The fracture is surface initiated. The load at yield is shown to be dependent on temperature and displacement rate. The load at yield increases with increasing strain rate and decreases with increasing temperature. Notched tension specimens are shown to exhibit an initially elastic behavior. Mildly notched specimens tested at room temperature are shown to fail in a ductile manner similar to un-notched specimens. More severely notched specimens, and the moderately notched specimen tested at 100° C are shown to fail in a brittle manner where the brittle failure is found to be internally initiated. The un-notched and notched tension test data together with simulation results enabled construction of ductile and brittle fracture criteria. A ductile failure criterion of maximum strain is proposed. This maximum strain is seen in the ductile failures of both the un-notched and the mildly notched specimens and has a value of approximately 0.65. A temperature dependent brittle failure criterion is proposed. This brittle failure criterion establishes critical values of negative pressure for brittle failure at various temperatures. Rubber-modified compression and tension specimens are shown to exhibit stress-strain and load-displacement behavior similar to that seen for the un-modified material compression and tension tests respectively. The elastic modulus, yield stress, amount of strain softening, and strain hardening are all seen to decrease with increasing rubber volume content. The inclusion of sub-micron rubber particles is shown not to dramatically enhance the mechanical properties of un-notched or mildly notched specimens. The inclusion of sub-micron rubber particles is shown to drastically increase the displacement to failure of more severely notched specimens tested at room temperature, but is shown to provide little improvement for tests conducted at -60° C.
by Michael DeShawn Johnson.
S.M.
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Cupta, Mark Glenn. "Photoacid Generators for Catalytic Decomposition of Polycarbonate." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10448.
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It is the goal of this body of work to research an assortment of different photoacid generators (PAGs) and quantify their ability to perform the decomposition of poly(propylene carbonate) (PPC). Adding PAGs to PPC allows for a decreased polymer decomposition temperature, which can in turn be used as a sacrificial polymer for the fabrication of various microelectromechanical and microfluidic devices. A focus will be placed on relating the properties of the PAG such as acid strength, acid volatility, and PAG activation to processing issues like percentage of total film decomposition, amount and composition of film residue, decomposition rate, decomposition temperature, and environmental dependencies. This research discovered that the use of superacid triflic and nonaflic based PAGs were not adequate for the decomposition of PPC due to the high vapor pressure of the acid. Furthermore, the non-fluorinated sulfonic acid based PAGs do not posses the super-acid level acidity needed to sufficiently decompose PPC. Conversely, a perfluorinated methide and a tetrakis(pentafluoropheyl)borate based PAG both demonstrated the capability for high level PPC decomposition. Building on the knowledge gained through experimentation with these individual PAGs, the creation of a novel Combination PAG was accomplished. The Combination PAG uses acid groups with different physical properties collectively working to achieve what neither could complete individually.
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Chow, Jimmy T. "Environmental assessment for bisphenol-a and polycarbonate." Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/368.
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Belcadi, Mohammed. "Comportement mécanique du polycarbonate prédéformé par laminage." Poitiers, 1990. http://www.theses.fr/1990POIT2317.
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La modification des proprietes mecaniques des polymeres sous l'effet d'une deformation plastique a temperature ambiante demande a etre connue, non pas seulement pour les applications de mise en forme qui restent peu developpees a ces temperatures, mais surtout pour une meilleure analyse des phenomenes de fissuration notamment en fatigue dans lesquels elle peut jouer un role determinant. Comme il n'est pas possible d'obtenir des faibles deformations par traction a cause d'une tres importante striction, nous avons utilise le laminage pour preparer des plaques deformees de 18% ou 46% a partir d'un polycarbonate recuit. Des eprouvettes de traction ont ete prelevees selon trois directions (0,/4 et /2) par rapport au sens long, pour mesurer les grandeurs elastiques (module d'young) et plastiques (seuil d'ecoulement et comportement uniaxial, allongement a la rupture, contractions transversales). Le trait le plus marquant apres laminage, par rapport a l'etat recuit, est la chute du seuil d'ecoulement plastique et la disparition simultanee de l'instabilite de deformation. La loi de comportement est decrite par une exponentielle. L'anisotropie des proprietes est mise en evidence et l'ecrouissage apparait a dominante cinematique. D'un point de vue physique, l'orientation moleculaire, si elle permet d'expliquer l'anisotropie et l'ecrouissage, ne rend pas compte d'importantes differences avec l'etat recuit, notamment sur les valeurs du module d'young et du seuil d'ecoulement plastique extrapolees a deformation nulle: le laminage prealable a laisse une structure plus facilement deformable (dislocations?). Enfin, d'un point de vue technologie, le laminage confere au polycarbonate d'excellentes proprietes d'emboutissabilite (avec cependant l'inconvenient de retours elastiques importants) et probablement une tenacite elevee
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Cheng, Chih-Min. "Irreversible deformation processes in rubber-toughened polycarbonate." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1061566661.
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Grewell, David A. "Laser Microwelding of Polystyrene and and Polycarbonate." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1396276070.
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Lionti, Krystelle. "Élaboration d’un revêtement dense et protecteur sur polycarbonate." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10225/document.
Full textAbstract:
Ce travail s’intéresse a la synthèse et à la caractérisation de revêtements hybrides O/I à base de silice, préparés par voie sol-gel et déposés sur polycarbonate (PC), pour des applications en milieu chaud et humide dans le domaine culinaire. Le PC étant connu pour sa sensibilité à l’hydrolyse dans ce type de milieux (provoquant sa dépolymérisation progressive et ainsi la libération de bisphénol A, molécule suspectée comme étant toxique), le rôle du revêtement est donc de protéger le PC et d’éviter son vieillissement prématuré, tout en améliorant ses propriétés mécaniques. Dans un premier temps, de nombreux sols ont été synthétisés et optimisés, principalement en termes de nature et quantités de précurseurs, et de pH, dans le but d’obtenir des revêtements homogènes et transparents. Un suivi des réactions d’hydrolyse et de condensation des sols a également été réalisé afin de déterminer le temps minimal de maturation de ces derniers. Apres dépôt des revêtements par dip-coating, les propriétés mécaniques des films ont été étudiées par de nombreuses techniques. D’un point de vue général, les propriétés des échantillons revêtus ont été trouvées supérieures à celles du PC nu. L’influence de nombreux paramètres de synthèse comme le ratio organoalcoxysilane(s)/silice colloïdale, l’ajout d’additifs, le type de traitement de surface du PC pré-dépôt ou encore les conditions de recuit, a également été étudiée. L’ensemble de ce travail a permis d’obtenir, à partir de deux systèmes sol-gel différents, des revêtements performants en termes de transparence, d’adhésion au substrat, de non-toxicité, couplés à des valeurs élevées de dureté, de densité et de module de YoungThis work deals with the synthesis and the characterization of hybrid O/I silica coatings prepared by the sol-gel route and deposited on polycarbonate (PC), for applications in hot and humid environment in the alimentary field. PC is well-known for undergoing hydrolysis in such conditions (causing its progressive depolymerization and thus leading to the release of bisphenol A, a molecule suspected to be toxic): the function of the coating would thus consist in preventing PC from this kind of premature ageing, along with the enhancement of its mechanical properties. As a first step, a lot of different sols were synthesized and optimized, mainly in terms of type and quantity of precursors, along with the pH, in order to obtain transparent and homogeneous coatings. The hydrolysis and condensation reactions were monitored in order to determine the minimum ageing time to be waited before any film deposition. After deposition by dip-coating, the mechanical properties of the films were assessed by using many different techniques. Basically, the coated-PC samples display higher properties than the uncoated one. The influence of numerous synthesis parameters such as the organoalkoxysilanes/colloidal silica ratio, the presence of additives, the kind of surface treatment of PC before film deposition, or the annealing conditions was also studied. This whole work led to the synthesis, from two different sol-gel systems, of superior quality coatings in terms of transparency, adherence to the substrate, non-toxicity, along with elevated hardness, density and Young’s modulus values
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Phelps, Andrea Lee. "Metal catalyzed copolymerization processes involving carbon oxides as substrates." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2531.
Full textAbstract:
Studies concerning two different copolymerization processes are detailed in this
dissertation: propylene oxide/CO2 coupling to afford poly(propylene carbonate) and Nbutylaziridine/
CO coupling to afford poly-??-butylalanoid. The copolymerization of
propylene oxide and CO2 to form the industrially useful poly(propylene carbonate) has
been investigated employing chromium(salen)N3 complexes as catalysts. Unfortunately
the reaction could not be studied in real time via in situ infrared spectroscopy, thereby
obtaining detailed kinetic data, because of the copolymer-limited solubility in most
solvents. Studies employing batch reactor runs concentrating on varying the cocatalyst,
the equivalents of cocatalysts, and the steric and electronic structure of the catalyst
through modification of the salen ligand were undertaken. It was discovered that the
optimal catalyst for copolymer selectivity vs. the monomeric propylene carbonate was
one that contained a salen ligand with an electron withdrawing phenylene backbone and
electron donating tert-butyl groups in the phenolate rings. This catalyst was used to
investigate the effect of altering the nature of the cocatalyst and its concentration. The coupling of carbon monoxide and aziridines has been shown to be selective
for comonomer-alternating enchainment in the presence of PhCH2C(O)Co(CO)4 to
afford poly-??-peptoids. The mechanistic aspects of the reaction of CO and Nbutylaziridine
by means of in situ infrared spectroscopy employing CH3C(O)Co(CO)3L
(L = PPh3 and P(o-tolyl)3) as precatalysts was investigated. It was found the PPh3
precatalyst exists in solution under catalytic conditions as an equilibrium mixture of
CH3C(O)Co(CO)3PPh3 and CH3C(O)Co(CO)4, and affords both poly-??-butylalanoid and
the corresponding lactam as a side-product. By way of contrast, the P(o-tolyl)3
precatalyst which possesses the sterically bulky and labile phosphine ligand, affords only
the acyl cobalt tetracarbonyl species in solution during catalysis with the selective
production of the copolymer. Kinetic studies conducted with CH3C(O)Co(CO)3P(otolyl)
3 showed the coupling reaction to have a first order dependence on catalyst, a first
order dependence on N-butylaziridine, and only a slight dependence on the concentration
of CO over the pressure range 17-69 bar. The working mechanistic model for the
copolymerization reaction involves first aziridine insertion into the cobalt-acyl bond, rate
determining ring opening by the cobaltate species, followed by the migratory CO
insertion.
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Gedler, Chacón Gabriel Eduardo. "Development of polycarbonate multifunctional foams with graphene nanoplatelets." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/397689.
Full textAbstract:
The goal of this research was to determine the relations between processing, structure and
properties of polycarbonate-graphene nanoplatelets (PC-GnP) foams. Using two different foaming
processes (in one and two steps) using supercritical carbon dioxide (scCO2) as a physical foaming
agent, a series of foams were prepared and investigated. The effects of processing variables (P, T
and time) and the materials composition (% GnP) on the cellular morphology, microstructure and
properties of the foams were investigated. The addition of GnP promoted cell nucleation in PC,
allowing the preparation of foams with a broad range of relative densities, varying from 0.07 to
0.80, with average cell sizes ranging from a few to hundreds of micrometers. Changes in PC
microstructure during processing in the presence of CO2 and GnP were investigated as well as the
variation of the thermal stability of the foams. At the microstructural level, the foams prepared in
two steps (typical foaming temperature of 165 ºC) the foams remained amorphous, while the foams
prepared in one step with typical foaming temperatures above 200 ºC, developed a degree of
crystallinity. The thermal stability of the foams was observed to be higher when compared with the
thermal stability of the unfoamed material, attributed to the thermal insulator effect of the cellular
structure. In addition, the presence of GnP delayed the diffusion of gaseous products due to the
barrier effect. These enhancements suggest the use of these foams in higher temperatures when
compared with PC. The influence of density, morphology and microstructure on the mechanical and
transport properties of the foams was analyzed. Regarding the viscoelastic properties of foams, it
was observed different linear relations in terms of their storage modulus with density, depending on
the density, composition and cellular morphology. The crystallinity in the foams prepared in one
step allow to explain the stiffer nature when compared with the foams prepared in two steps,
regardless of their comparatively smaller cell densities and larger cells. Regarding the electrical
conductivity, in addition to the content of conductive nanoparticles, the effect of the cellular
structure on the electrical conductivity of the foams was evident. The enhancement of conductivity
while reducing the relative density of foams, suggesting the formation of a more effective
conductive network, resulting from a better dispersion and/or distribution of nanoparticles when
increasing the expansion ratio. This effect was also observed in the electromagnetic interference
(EMI) shielding properties. In the case of the thermal conductivity, it was mainly controlled by
foam densities, while the cellular morphology of foams had a smaller impact. It was observed a
reduction of 90 % in density of pure PC promoted a reduction in thermal conductivity of 80 %
approximately. The addition of a small fraction (0.5 wt%) of GnP promoted up to 95%
enhancement of the thermal conductivity as compared to pure PC foams with similar relative densities. This was attributed to a better thermal conductivity through the solid fraction with GnP.
The addition of higher GnP contents (5 wt%) led to foams with thermal conductivities similar to
that of the unfoamed composite (5 wt%). These results suggest the use of PC-GnP foams could be
considered for applications where dissipation of heat is needed while using lightweight materialsEste trabajo fue llevado a cabo con el objetivo de determinar las relaciones entre procesado, estructura y propiedades de los nanocompuestos espumados de policarbonato con nanoparticulas de grafeno (PC-GnP). Se prepararon e investigaron series de espumas producidas según dos procesos diferentes de espumación (proceso en una etapa y en dos etapas) usando dióxido de carbono supercrítico (scCO2) como agente físico de espumación. Se analizaron los efectos de las variables del proceso (presión, temperatura y tiempo) y de la composición del material (% GnP) sobre la morfología, estructura y propiedades de las espumas. La incorporación de GnP favoreció la nucleación celular en el polímero, permitiendo preparar espumas con un amplio rango de densidades relativas, entre 0.07 y 0.80, con tamaños celulares promedio de entre unos pocos micrómetros hasta varios cientos. Se investigaron, asimismo, los cambios microestructurales desarrollados por el PC durante el procesado en presencia de scCO2 y GnP, así como la variación de la estabilidad térmica de las espumas. A nivel estructural, en el caso de espumación llevada a cabo en dos etapas (Temperatura típica de espumación 165 ºC) las espumas no desarrollaban cristalinidad, mientras que las espumas producidas directamente en una etapa, con temperatura típica de espumación superior a 200 ºC, presentaban un grado de cristalinidad. La estabilidad térmica de las espumas resultaba superior a la del material no celular, debido al efecto aislante de la estructura celular. Asimismo, las nanopartículas GnP limitaban la difusión de los productos gaseosos por efecto barrera. Ello sugiere, para estas espumas, eventuales aplicaciones de mayor temperatura que las del propio PC. Por otra parte, con respecto a las propiedades termomecánicas de las espumas, se encontraron diferentes relaciones entre los valores del módulo de almacenamiento con la densidad, dependiendo de la densidad, composición y morfología celular. Asimismo, la cristalinidad desarrollada en las espumas producidas en el proceso de una etapa, permitió explicar su mayor rigidez frente a las producidas en dos etapas, a pesar de tener menores densidades celulares y superiores tamaños de celda. Por lo que respecta a la conductividad eléctrica, además de la concentración de partículas conductoras GnP, se evidenció la influencia de la estructura celular de la espuma como una característica relevante sobre dicha propiedad. Así, se puso de manifiesto el aumento de la conductividad al disminuir la densidad relativa de las espumas, sugiriendo una red de conducción eléctrica más efectiva, que resultaría de una mayor dispersión y/o mejor distribución de las partículas al aumentar el grado de espumación. Este efecto se pudo observar sobre las propiedades de protección frente a la interferencia electromagnética (EMI-SE). En el caso de la conductividad térmica, esta fue determinada principalmente por la densidad relativa de las espumas y, en menor medida, por su morfología celular. Así, una disminución del 90 % en la densidad del material conllevó una reducción de la conductividad térmica de un 80% aproximadamente. De igual modo, una fracción másica tan pequeña como un 0.5 % de GnP promovió hasta un 95% de incremento de conductividad térmica en espumas de similar densidad. El efecto se atribuye a una mejor conducción de la fase sólida que contiene las partículas GnP. En este sentido, las espumas con contenidos de GnP del 5 % en peso, manifestaron conductividades térmicas del mismo orden que las del compuesto no celular sin espumar. Estos resultados sugieren eventuales aplicaciones para las espumas de PC-GnP donde se requiera disipación de calor con materiales ligeros
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Silberstein, Meredith N. "Mechanics of Notched Izod impact testing of polycarbonate." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32917.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 62).
Polycarbonate is widely used as a transparent protective material because of its low density and excellent mechanical properties. However, when defects such as cracks or notches are introduced, it is subject to catastrophic brittle failure at relatively low loads. Notched Izod testing is a common qualitative measure of toughness of a material, measuring energy absorbed prior to failure under high triaxiality and high rate loading conditions. Much research has been done using Izod testing to compare the fracture energies of blends of Polycarbonate and rubbery materials; however the specific yielding and fracture mechanisms associated with each blend are rarely analyzed. This study presents detailed images, fracture energies, and time durations of the deformation and failure processes actively occurring during the Notched Izod testing of 3.23mm and 6.35mm thick Polycarbonate specimens, as well as of a quasi-static version of Notched Izod bending. The thin specimens were found to yield in a ductile manner followed by tearing across most of the ligament width, resulting in a final failure including a small plastically-deformed ligament hinging the two failure surfaces in both the Notched Izod impact and Quasi-Static tests.
(cont). The thick specimens exhibited slight yielding followed by catastrophic failure, where the crack initiated ahead of the notch and then propagating back towards the notch root as well as across the remaining ligament.. In the thick Izod tests local pre-failure yielding was evident at the notch root resulting in extensive blunting of the notch. The fracture energies per unit thickness for the thin specimens were almost a full order of magnitude larger than those for the thick specimens. A finite element simulation for the Notched Izod Impact test was developed using the Arruda and Boyce(1988) constitutive model of polymers as modified by Mulliken and Boyce(2004) for high rate deformation. The 3.23mm Notched Izod impact test was successfully modeled from initial contact of the pendulum through initiation of failure and early tearing. The yielding patterns and failure occurred along the same lines as in the experiment where diagonal shear bands and lobes initiate plastic deformation from the notch tip and tearing progresses in a horizontal manner across the specimen width. An extensive shear yielded region is observed ahead of the propagating tear. The 6.35mm thick model shows the beginning of the formation pressure concentration which causes brittle fracture, but further refinement of the mesh needs to be performed for more accurate modeling.
by Meredith N. Silberstein.
S.B.
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Knauss, Daniel M. "Synthesis and characterization of new polycarbonate material systems." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40208.
Full textAbstract:
Bisphenol A polycarbonate is an engineering thermosplastic which can be utilized for a variety of applications. Modifications to improve upon the properties of this useful material have been attempted since its invention. Three modifications of bisphenol A polycarbonate and its copolymers have been examined in this work.
The hydrolytic stability of copolymers of polydimethylsiloxane and polycarbonate was improved by the synthesis of pre-formed phenol functional polydimethylsiloxane oligomers in which the Si is attached directly to the aromatic ring of the hydroxyaryl functional component. In situ random block copolymers of polydimethylsiloxane and polycarbonate were synthesized by interfacial polymerization techniques. The Si-aryl bonds of the novel polydimethylsiloxane oligomers were found to impart good thermal and hydrolytiC stability to the random block copolymers.
Terminally reactive polycarbonate oligomers were also synthesized in order to form polycarbonate network materials. 4-Acetoxystyrene was utilized as a stable precursor to 4-vinylphenol which could then be used to quantitatvely control the molecular weight and functionality of the polycarbonate chains. The reactive oligomers were found to undergo a thermal cure above the respective glass transition temperatures to form insoluble networks. These network materials were found to have superior solvent resistance as compared to the linear material while retaining much of the useful mechanical properties (high fracture toughness, etc.) of bisphenol A polycarbonate. Furthermore, the glass transition temperatures of the networks were found to increase with a decrease in the molecular weight between crosslinks.
The fire resistance properties of polycarbonate were modified by the copolymerization of bisphenol A with phenol derivatives of triphenylphosphine oxide. The effect of changes in the composition were determined by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature, as well as the residual char yield at elevated temperatures was found to increase with an increase in the phosphorus monomer content as measured by the two respective methods. Cone calorimetry was also performed on the samples to determine the heat release rate, which reflected an increase in the fire resistance properties with an increase in the phosphorus content.Ph. D.
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Farmer, Robin Sandra. "A Study of Crystallization in Bisphenol-A Polycarbonate." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35996.
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The crystallization behavior of bisphenol-A polycarbonate (BAPC) was studied, focusing on the initial stage of crystallization and the secondary stage of crystallization. Bisphenol-A polycarbonate was the polymer chosen for this study because of its slow crystallization rate. With slow crystallization kinetics, the polymer morphology does not change when quenched below its glass transition temperature, enabling the study of different stages of crystallization through the frozen morphology.
The study of the initial stages of crystallization pertained to crystallization times prior to the growth of detectable crystallinity. This study employed BAPC because of the long induction period, a direct result of the slow crystallization kinetics. During the induction period of polycarbonate crystallized at 190°C there was no evidence of polymer chain ordering that was seen in literature for other polymers. The length of the induction period determined by differential scanning calorimetry and wide-angle X-ray diffraction varied by over 6 hours because differential scanning calorimetry can detect a smaller amount of crystallinity than wide-angle X-ray diffraction. Signs of pre-ordering in the literature could be a result of experimental sensitivity.
The study of the secondary crystallization dealt with the isothermal lamellar thickening of BAPC crystals during annealing, after crystallization for an extended period of time. Small-angle X-ray scattering and differential scanning calorimetry experiments were performed on bisphenol-A polycarbonate samples crystallized near 190°C for 8 days and annealed at either 223°C or 228°C for various times. The Gibbs-Thomson relationship, which can be defined using the experiments mentioned, yielded two thermodynamic constants, the equilibrium melting temperature and the surface free energy. Including data from literature in the determination of the constants, the equilibrium melting temperature and surface free energy of BAPC is 303°C and 36.6mJ/m2, respectively. Comparing the lamellar thickness measurements by small-angle X-ray diffraction with direct measurements by microscopy was difficult because the morphology of the polymer was not easily seen in the bulk using atomic force microscopy or scanning electron microscopy. Etching the sample was the most promising technique for future investigations of revealing the bulk morphology for direct lamellar thickness measurements. Crystallizing thin films of polycarbonate on calcite substrates allowed the measurement of lamellar thickness using scanning electron microscopy because the lamellae grow epitaxially to the substrate. The measurement of the long spacing in thin film samples was comparable to that of bulk samples.Master of Science
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Al-Lafi, Waleed. "Performance of polycarbonate nanocomposites at high strain rates." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9699.
Full textAbstract:
This project was conducted in order to develop high-performance (Polycarbonate (PC) based nanocomposite) materials at high strain rate, for potential applications in military, sports and personal protection. In this project, a series of PC nanocomposites were successfully fabricated by melt compounding method. The two kinds of nanofillers namely Na + montmorillonite clay and chemically modified multiwalled carbon nanotubes with hydroxyl group (MWCNTs-OH), respectively, were employed to fabricate polymer nanocomposites. A number of techniques including wide angle X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), modulated differential scanning calorimetry (DSC), were employed to study microstructure and morphology of these nanocomposites. Mechanical properties at low and high strain rates of these nanocomposites were mainly investigated. The SEM images revealed that uniformly dispersion and distribution of CNTs in nanoscale have been achieved in PC or high density polyethylene (HDPE) matrix. By means of DSC studies, the 'nanoeffects' on the glass transition temperature of PC and crystallinity of HDPE were examined and discussed. A simple method to detect state of dispersion of nanofiller in polymer matrix by the comparison of the values of bulk density determined theoretically and experimentally, respectively has been established. The dynamic mechanical behaviours of PC and its nanocomposites with MWCNT and clay nanofillers were analysed with temperature and frequency. The addition of the nanofillers has significant influence on the dynamical response of the PC to temperature and frequency. The results revealed that MWCNT and clay nanofillers can enhance the storage modulus and decrease the damping property of the PC. Abstract ii The addition of MWCNTs has significant influence on the impact performance of PC and HDPE at a quasi-static rate revealed by an instrumented falling weight impact test (IFWIT). The results indicated that the maximum load of PC is significantly improved by the filler. The PC specimen containing 1 wt% MWCNTs showed the highest peak load value of approximately 884N, much higher than 209N of the pure PC. The PC nanocomposites are able to sustain much higher external force before fracture, and the behaviour contributes to greater deflection. The increased filler content leads to higher impact force due to the particle interface react and form a tortuous fracture path. The incorporation of MWCNTs causes a significant improvement of impact failure energy of the PC. Incorporation of 1 wt% MWCNTs caused significant improvement of 500% in impact failure energy. The performance of the PC and HDPE nanocomposites were examined by means of Split Hopkinson Pressure Bars Apparatus. The strain rates from 102 to 104 s -1 were used. For PC/clay nanocomposites, a slight enhancement in yield stress was observed. Yield stress decreases with increasing strain at a certain range of strain rates. In addition to increasing the strain rate, the process of strain hardening dominates the plastic deformation and then thermal softening upon reaching stress collapse. The region of thermal softening was increased with the increase of strain rate. Similar conclusions were drawn for the PC/MWCNT nanocomposites. Yield stress decreases with increasing strain at a certain level of strain rate. Moreover, with an increase in MWCNT content, the temperature effect on the performance of the PC appeared. For HDPE/MWCNT nanocomposites, it is clear that the high strain rate and high MWCNT contents have a significant influence on the performance of the HDPE. The rapid decrease in yield stress was observed due to the temperature effect. From our results, we concluded that polymer nanocomposites could be used for the minimisation of the trauma injury at certain impact rates as results of significant improvement on the performance of PC matrix by adding nanofiller. At very high impact rates, the function of nanofillers could vanish due to temperature effect.
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Schuchert, Ingrid U. "Elektrochemische Untersuchungen zur Abscheidung und zum Korrosionsverhalten von Kupfermikrostrukturen." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962730688.
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Fateh, Razan [Verfasser]. "Transparent self-cleaning coatings on polycarbonate surfaces / Razan Fateh." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2014. http://d-nb.info/1063728134/34.
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Wright, Stuart Charles. "High strain rate response and ballistic impact of polycarbonate." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335252.
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Robinson, Alexander M. "Blends of Poly(ethylene terephthlate) with bisphenol-A polycarbonate." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/6749.
Full textAbstract:
Blends of Poly(ethylene Terephthalate) with Bisphenol-A-Polycarbonate The objective of the study was to determine the extent to which bisphenol-Apolycarbonate (PC) influences the rheology, processing behaviour and subsequent crystallinity and mechanical properties of poly(ethylene terephthalate) (PETP) in the 'compatible' region, when the polycarbonate is the minor blend component. Also, further characterisation of this blend system, in terms of miscibility and micro- structure development was required. After careful drying in a desiccant-type hopper drier melt-phase, blending was carried out using a twin-screw extruder with a purpose-designed screw configuration. Blends were made up at three levels (PETP/PC); 85/15,80/20 and 75/25 using three different molecular weights of PC, and virgid-materials were also included in the study. The extrudates were then dried and injection moulding was carried out under various conditions, which were chosen to modify the degree of order in the crystallisable phase. The effects of PC on the shear-flow behaviour of the blends was examined, and in general the PETP/PC 80/20 blends demonstrated lower shear viscosities than expected from additivity. Otherwise the shear flow behaviour was generally consistent with blend composition. Thermal analysis and crystallisation behaviour of the blends were investigated to determine the effects of PC on the crystallisability of the blend and the PETP T. Solid state isothermal crystallisation behaviour was studied using a modified thermal analysis technique. Crystallisation of the PETP portion of the blend was shown to be impeded by PC. A specific and rapid technique has been developed to determine depth-dependent orientation distributions Three dimensional analyses of birefringence were obtained for moulded plaques of various PETP/PC blends. The orientation distribution was in accordance with the flow pattern during processing and was noticeably planar in nature. However, the level of orientation in the mouldings investigated was very low. Thermal analysis and microscopy techniques indicate there is no evidence for miscibility in the blends. The effect of PC molecular weight and content on mechanical properties of the blend was investigated. Generally, the PETP/PC blends exhibited improved toughness, in terms of total energy absorbed, and the properties were influenced further by the degree of crystallinity. It has been shown that mechanical properties of the blend deteriorate rapidly when samples are stored for extended periods in water at 70'C. Due to the PET? portion in the blends crystallising, and hydrolysis, the samples pass into the brittle mode. The addition of PC to PETP was found to modify the thermoelastic behaviour. Addition of PC permits thermoelastic processing of PETP/PC blends over a wider temperature range than would be suitable for PETR Also, the addition of PC appears to accelerate the onset of strain-induced crystallisation in the PETP.
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Stamp, Louise Michelle. "Alkene synthesis and polycarbonate formation in supercritical carbon dioxide." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619690.
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Cannon, Michael J. "Transesterification of poly(ethylene terephthalate) and bisphenol-A-polycarbonate." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/2589/.
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Blends of Poly(ethylene terephthalate) (PET) and bisphenol-A-polycarbonate (PC) have been made by solution and melt blending and these blends were subject to isothermal heating to induce a transesterification reaction. The raw materials and products of this reaction have been studied by a variety of different methods to ascertain the chemical, physical and mechanical properties they possess. The conclusions drawn are listed below. PET and PC are immiscible but are compatibilised by transesterification. Transesterification is a second order reversible process and is fast only when water is present, when absent the rate of transesterification is so slow that little or no reaction is observed in after 60 minutes at 300 c. When water is present in the blend significant chain scission and degradation takes place, this is not observed in the absence of water• The material obtained from melt blending has a molecular weight higher than that of commercial PET and it is possible to increase it further by standard solid state polymerization techniques. The PC concentration in PET is critical to the existence and extent of crystallisation. PET blends containing 10% PC are not significantly stronger or weaker than commercial PET and perform very similarly to the yield point. PET blends containing 10% PC are less ductile than commercial PET and will therefore fail sooner when they have yielded under tension. PET blends containing 10% PC do not injection mould as well as commercial PET under conventional procedures for PET, surface crazing and voiding is observed.
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Steer, Philippe. "Viscoplasticité dynamique du polycarbonate aux grandes vitesses de sollicitation." Lille 1, 1985. http://www.theses.fr/1985LIL10143.
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Zhou, Tingting. "Mechanical Analysis of Polycarbonate/Polysiloxane Block Copolymers and Blends." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26869.
Full textAbstract:
Polydimethylsiloxane (PDMS) can be used to react with polycarbonate (PC) to generate PC-PDMS multiblock copolymers and PC/PC-PDMS-PC triblock blends to overcome the notch sensitivity of PC while maintaining its transparency. It was found in this study that PDMS can act as a rubber particle to absorb energy and promote multicrazing. As a result, the incorporation of PDMS can increase PC's toughness. Meanwhile, high optical clarity can be observed even at 62 wt% PDMS in the multiblock copolymers with uniform morphology. However, PC/PC-PDMS-PC triblock blends damage PC's transparency and become opaque due to the phase separation. Furthermore, compared to compression molding, injection molding introduces shear due to the decrease of the area at the nozzle, which leads to the orientation of polymer chains and, subsequently, better properties of specimens.
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Zhang, Wei. "Sustainable Polycarbonate Nanocomposites: Impact of Production Method and Composition." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1417954859.
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CROS, PIERRE-EMMANUEL. "Comportement sous impact d'assemblages en polycarbonate et en polyurethanne." Université Louis Pasteur (Strasbourg) (1971-2008), 2000. http://www.theses.fr/2000STR13229.
Full textAbstract:
Les feuilletages sont aujourd'hui couramment utilises dans l'industrie car ils permettent de limiter les phenomenes de fragilisation et d'augmenter l'efficacite massique d'un vitrage face a un choc. L'objectif de la these est d'etudier les modes de deformation et de rupture de cibles en pc et en assemblage pc/pu/pc afin de determiner le role de l'elastomere dans l'assemblage lors d'un impact et de developper un modele pour simuler la perforation d'une cible par un projectile. Une campagne d'essais balistiques en temperature a ete menee afin de determiner le comportement sous impact face a un projectile spherique en acier. Des essais de caracterisation statique et dynamique ont ete effectues sur des echantillons en polycarbonate et en polyurethanne et ont permis d'identifier un modele qui a ete implante dans un code par elements finis. Ce modele couple a un critere d'erosion a ete valide sur des cibles minces en polycarbonate a differentes temperatures et pour des ruptures ductiles par petalisation. Sur des cibles epaisses et pour des temperatures basses, proches de la transition ductile / fragile, on observe des modes de rupture par bouchonnage et il est necessaire dans la simulation, de diminuer le seuil de deformation plastique a rupture avec la vitesse incidente du projectile en cas de perforation. Le comportement sous impact des assemblages dans la gamme de temperature etudiee montre que le polyurethanne ne transmet que les contraintes en pression et absorbe les contraintes en cisaillement, ce qui augmente la capacite de l'assemblage a se deformer sans se rompre. La presence du polyurethanne rend les performances balistiques plus sensibles a la temperature au voisinage de la transition vitreuse par rapport a des cibles en polycarbonate d'epaisseur equivalente. L'observation des facies des assemblages apres impact indique des modes de rupture par petalisation caracteristiques de cibles monolithiques minces, quelle que soit l'epaisseur de polyurethanne.
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Clay, Stephen B. "Effect of ultraviolet exposure on the durability of polycarbonate." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06302009-040551/.
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Christmann, Anne. "Elaboration et propriétés de nanocomposites transparents à matrice polycarbonate." Montpellier 2, 2007. http://www.theses.fr/2007MON20126.
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Cette étude porte sur l'élaboration de nanocomposites transparents à matrice polycarbonate et repose sur deux objectifs antagonistes : le renforcement mécanique par incorporation de nanoparticules minérales et la conservation des propriétés optiques du polycarbonate. La présence de nanoparticules minérales (silice, alumine et carbonate de calcium) dans la matrice induit une augmentation du module élastique des matériaux ; cependant, la résilience et les propriétés optiques se trouvent diminuées en raison d'un manque d'interactions à l'interface matrice-particules. Des traitements de surface ont été réalisés sur les nanoparticules permettant l'amélioration significative des performances mécaniques et optiques des nanocomposites, la nature du traitement de surface est déterminante. De plus, dans le cadre d'une réflexion plus générale sur le comportement mécanique des nanocomposites, une étude a mis en évidence l'influence des particules nanométriques sur les propriétés mécaniques des composites et sur les mécanismes d'endommagement et de localisation des déformations au sein des nanocomposites au cours d'un essai de traction uniaxiale
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Pionnier, Nicolas. "Amélioration des propriétés antibuée du polycarbonate transparent par traitement topographique." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC043/document.
Full textAbstract:
La présence de buée sur des surfaces transparentes altère la transmission de la lumière. La buée est un ensemble de gouttes condensées sur une surface froide. Ces gouttes absorbent, réfléchissent et diffractent la lumière, réduisant la transparence de la surface sur laquelle elles se sont formées. Ce phénomène peut, en fonction des applications, causer des problèmes esthétiques et de sécurité. Une solution répandue dans le secteur industriel est l’utilisation de revêtements chimiques. Mais cette approche à un coût ; elle oblige à ajouter une nouvelle étape sur la chaine de production. Une autre solution, celle choisie durant ce doctorat, est l’approche topographique. En contrôlant la topographie par texturation de surface, les propriétés de mouillage peuvent être pilotées. Ainsi, des surfaces antibuées peuvent être développées. En fonction de la surface initiale, deux mécanismes sont possibles. Sur des surfaces hydrophiles, la création d’un film liquide uniforme remplaçant les gouttes d’eau est à privilégier. Avec ce type de film, la surface conserve de bonnes propriétés de transparence. Si la surface est plutôt hydrophobe, l’idée est de favoriser le déperlement des gouttes et ainsi d’évacuer l’eau le plus rapidement possible. Les travaux de ce doctorat portent sur le développement d’un traitement de surface topographique par injection plastique. Ce traitement vise à supprimer l’impact optique de la buée sur les surfaces en polycarbonate transparent des phares automobiles. L’une des contraintes majeures de ces travaux est de concevoir des texturations de surfaces facilement industrialisables. Les moyens de texturations doivent être adaptésThe presence of dew on transparent pieces impairs light transmission. Dew is a group of droplets condensed on cold surfaces. These droplets absorb, reflect and diffract light, reducing condensation surface transparency. This can cause aesthetic or security issues. The most widely used method currently for improving transparency of surfaces covered with dew is to apply anti-fog chemical coatings. These coatings suppress the whitish opaque layer caused by condensation by reducing the surface tension of water droplets, causing them to disperse into a thin liquid sheet. However, this solution is expensive. It is adding a step in the production line. Surface texturing offers a viable alternative to the use of chemicals. Controlling the surface topography by modifying textured allows wetting property management. This approach, chosen during this PhD thesis, allows the design of anti-fog surfaces. Depending on the surface, two droplets suppression mechanisms are possible. On hydrophilic surfaces, liquid sheet formation replacing droplets has to be favored. If the surface is hydrophobic, droplets sliding off should be increased, thus water evacuation will be faster. Our work consists in the development of a topographical surface treatment by molding injection. The aim is to limit the optical impact of the dew on transparent polycarbonate surfaces of car headlights. The major constraint of this work is to design easy industrialized textured surfaces. Production means must be adapted
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Zhao, Xiaomin. "Formaldehyde mass-transfer properties study." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51597.
Full textAbstract:
Formaldehyde, an important feedstock in industrial processes and manufacture, is widely present in numerous consumer products. Emitted by many types of consumer products and indoor materials, indoor air can contain high concentrations of formaldehyde. Exposure to formaldehyde is hazardous to human health. Thus knowledge of formaldehyde mass-transfer properties is critical to efforts to reduce formaldehyde emissions and establish related standards and regulations.
The primary objectives of this project include: 1) documenting and validating procedures and methods for analyzing and measuring formaldehyde mass-transfer characteristics; 2) evaluating and comparing formaldehyde mass-transfer properties in different materials using micro-balance sorption/desorption tests; 3) investigating observed formaldehyde mass-transfer irreversibility and the recently developed formaldehyde polymerization theory.
The procedures and methods for analyzing and measuring formaldehyde mass-transfer characteristics were developed in an effort to minimize experimental variability and were strictly followed during the research. The formaldehyde mass-transfer properties of five polymer materials (polycarbonate, polystyrene, poly(methyl methacrylate), polyethylene and polypropylene) were measured through sorption/desorption testing. Results indicated that formaldehyde solubility was highest in polyethylene while the rate of diffusion was the highest in polypropylene. Results also showed that the diffusion process in the selected polymer materials was irreversible in all cases. Furthermore, additional testing showed no detectable polyformaldehyde formation on polymer surfaces after exposure to formaldehyde. The causes of observed mass-transfer irreversibility need further study.Master of Science
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Papka, Scott Duane. "In-plane uniaxial and biaxial crushing of a polycarbonate honeycomb /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Durand, Pierre-Luc. "Fatty acids as a source of original aliphatic polycarbonate materials." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0710.
Full textAbstract:
Cette thèse porte sur la valorisation de dérivés d’acides gras dans l’objectif d’élaborer des matériaux polycarbonates aliphatiques (PCAs) bio-sourcés originaux. Dans cette optique, deux plateformes de carbonates cycliques à 6 chaînons (6CCs) ont été synthétisés en utilisant des voies d’accès impliquant soit la formation d’un intermédiaire de type malonate ou un couplage entre un acide gras et le 2-amino-1,3-propanediol. La polymérisation par ouverture de cycle de ces monomères a été étudiée. La première plateforme de 6CCs a été polymérisée en présence de Sn(Oct)2 comme catalyseur, donnant accès à des polycarbonates de faible Tg allant de -61°C jusqu’à-26°C du fait de longues chaines latérales pendantes. La polymérisation de la seconde plateforme de6CCs a été effectuée de manière contrôlée en utilisant un système catalytique composé de la DBU et d’une thio-urée. Tirant profit de ces polycarbonates aliphatiques bio-sourcés linéaires porteurs d’insaturations, des matériaux originaux réticulés ont été synthétisés. Plusieurs méthodes de réticulation ont été testées telles que le couplage thiol-ène irréversible, la réaction de Diels-Alder thermo-réversible et la cyclo-addition photo-réversible [2+2] entre deux groupements cinnamate.Ainsi, des PCAs réticulés issus d’acides gras ont été synthétisés et caractérisés; ces derniers possèdent des propriétés physico-chimiques modulables selon la nature des monomères de départ etla densité de réticulation des réseauxFatty acids were derivatized with the objective to design bio-based aliphatic polycarbonate(APC) materials. To that purpose, two platforms of lipidic 6-membered cyclic carbonates were prepared following synthetic routes either involving the ring-closure of a malonate intermediate or the coupling reaction between a fatty acid and 2-amino-1,3-propanediol. The ring-openingpolymerization (ROP) of these cyclic carbonates was next investigated. The first platform of 6CCswas polymerized in the presence of Sn(Oct)2 as catalyst, yielding low Tg aliphatic polycarbonates ranging from -61°C to -26°C with respect to the size of the pendant aliphatic side chains. The polymerization of the second lipidic 6CC platform was performed in a controlled fashion using DBU/Schreiner thiourea as catalytic system. Taking advantage of the presence of unsaturation functions on the linear bio-based APCs, cross-linked polycarbonate materials were then prepared.Several cross-linking methods were tested such as the irreversible thiol-ene coupling, the thermoreversible Diels-Alder reaction and the photo-reversible [2+2] cyclo-addition reaction between two cinnamate moieties. Fatty acid-based cross-linked APCs were thus designed and characterized; the latter exhibit tunable physico-chemical properties as a function of the monomer structure and the cross-linking density
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Lu, Yong. "Modification of nanofillers and evaluation in polyurethane and polycarbonate nanocomposites." Aachen Shaker, 2008. http://d-nb.info/989220206/04.
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Nita, Elisabeta Maria Iuliana. "Structure and properties of reactive polycarbonate-poly(ethylene terephthalate) blends." Thesis, Manchester Metropolitan University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324144.
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Clark, Darren. "Formability of Polycarbonate." Thesis, 2008. http://hdl.handle.net/10012/4176.
Full textAbstract:
Current thermoplastic processing techniques involve high capital costs for moulds and
significant use of energy to melt or soften the materials. Single-step process cold
forming techniques, such as stretch forming, could be cost effective methods for
manufacturing large parts with shallow cross-sections from plastic sheet. The present
work is a preliminary investigation of a cold forming technique for polycarbonate.
The objective of this work is to characterize the bulk deformation behaviour of
polycarbonate using tensile tests and dome stretch forming tests. Two different
molecular weight polycarbonate sheets with 1.6 mm thickness were studied: (i) one with
Mw = 42,000 g/mol and (ii) the other with Mw = 52,000 g/mol. For the latter, 3.2 mm
sheets were also studied.
Tensile tests conducted at three different cross-head speeds, i.e., 2, 20 and 200 mm/min
showed very similar elastic and plastic deformation properties for the two molecular
weights. Correspondingly, the activation volumes at yield were almost identical. There
was also negligible difference in the thermophysical properties between the two materials
as found by differential scanning calorimetry.
Dome stretch forming tests were conducted on a metal forming machine. Specimens of
varying width were tested to give different strain states ranging from deep drawing to biaxial. The limiting dome height or the maximum level of stretch forming
iv
increases with specimen width. This is due to biaxial deformation which increases the
maximum strain. Forming limit diagrams (FLDs) were also constructed from the local
strains measured from printed fine circle grid patterns on the polycarbonate sheet
surfaces. The FLDs showed common general characteristics with metals except for a few
key differences. An area of very few data points was found to lie between the “safe
zone” and the “necked zone”. This void was referred to as the “unstable neck formation
zone”. It exists because of the large local increases in strain associated with the unstable
nature of polymer neck formation.
Much more study is required before polycarbonate can be cold formed at strains below
the unstable neck deformation. However, the materials and techniques used in this work
have demonstrated that the process can be viable for forming shallow large parts from
relatively thin thermoplastic sheet a as long as the local biaxial strains are less than 20%.
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Chung, Shung Shing, and 張雙燻. "Polycarbonate by transesterification." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/05317221643575690068.
Full textAbstract:
碩士國立成功大學
化學工程研究所
81
The polycarbonate (PC) resin can be producedby phosgenationand transesterification processes. Both processes have advantages and disadvantages. Because of environmental concern (toxicity of phosgene) in Taiwan,the transesterification process may be the choice in this location. In our transesterification study ,various catalysts were evaluatedwith changing operating parameters and the reactants ratios to develop the best process for the production of PC.The processes is applied in the synthesis of high performance PC derivatives (such as high Tg , high impact, low water absorption and still retain high transparency). It was found that alkaline catalysts induce side reaction and discolored the polycarbonate.The electron-donor catalysts (eg.4-Dimethyl-aminopyridine、2- Methylimidazole) were found to be excellent catalysts for the transesterification process. These catalysts not only promote polymerization but also minimize discoloration.To maximize polycarbonate heat stability ,the addition of specific antioxidants were found to be effective and the final product has high intrinsic viscosity (I.V)and high degradation temperature. Several PC derivatives with different glass transition temperatures(Tg) were synthesized by varying the main chain structure of polymer with intention of expanding the areas of PC application.
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CHEN, SHI-XIONG, and 陳世雄. "Polycarbonate complexed membrane." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/52596262900756069012.
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Huang, Jen-Kai, and 黃仁楷. "Characterisation of recycled polycarbonate /acrylonitrile butadiene styrene and polycarbonate/polybutylene terephthalate blends." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/5p3mc5.
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博士國立臺灣科技大學
材料科學與工程系
107
The drastically increasing quantity of waste generated caused by the rapid development of 3C products has a serious impact on the environment. For a better management of 3C product waste, the EU has not only developed a series of environmental protection directives e.g. WEEE, RoHS, and EuP, in 2006 but also requested all member states to complete their legislation before August 2007. In addition, the EU has also urged manufactures to build up green procurement specifications by taking advantage of the EU single market. To reflect the requirements laid down by the EU and for environmental protection, there is an increasing essence to explore the potential to recycle and reprocess the aforementioned materials. In the laboratory, reprocessing 6 to 8 times in small batches was frequently performed for verifying the physical and rheological degradation of PC, ABS and PC/ABS blends. The research results have evidenced that the polymeric material is subjected to heat and mechanical shearing force during processing, resulting in the molecular chain break and, consequently, decreases in tensile properties and the glass transition point (Tg). Nevertheless, the effects induced by heat, shear force and moisture during actual mass production vary frequently largely from those in the laboratory test. Therefore, the objective of this study was (1) to quantify the degradation of polymeric materials during actual mass reprocessing, (2) to elevate the recycling and reprocessing efficiency of the polymeric materials via the introduction of modifiers for the purpose of environmental protection and (3) to optimise the “cost to performance ratio”. PC/ABS blend (a.k.a CS) is one of the most popular engineering plastics to date, frequently considered as a good alternative to PC or ABS. To estimate the potential to recycle and reprocess CS, we characterised the thermal, rheological and mechanical behaviour of CS reprocessed 0 to 20 times in real industrial facilities and, furthermore, unprecedentedly attempted to modify the 20-time reprocessed CS until its functionality within 15% deviation from the virgin CS. Consistent thermal weight loss (30% at 300-450oC and 40% at ~470oC) and Tg points (at ~100oC) of CS from various cycles of reprocessing reflected the associated high thermal stability. However, increased stress values (from 4.71 to 5.23 kgf mm2) and melting index (from 40 to 66 g (10 min)1) but decreased stain (from 27.2 to 11.7 %), impact strength (from 87.7 to 14.2 J m1) and torque values (from 71 to 49 N m1) suggested that CS underwent Ⅲ polymer chain breaks during reprocessing and became stiffer. Recovery of the 20-time reprocessed CS was achieved by adding ~30% (w/w) virgin PC and ABS together with 1.5% (w/w) of chain extender and 2% (w/w) of styrene maleic anhydride (SMA) simultaneously. The study demonstrated the potential for recovering repeatedly reprocessed PC-based polymer blends and a new way of recycling polymer resource for environmental protection. Polycarbonate (PC)/polybutylene terephthalate (PBT) blends (CBs) represent a good compromise between the properties of PC and PBT and are among the most popular engineering plastics today. To evaluate the capability of recycled and reprocessed CBs, the physical and mechanical properties of 0 to 20 times reprocessed CBs were characterised, and an attempt was made to modify a 20-time reprocessed CB to reach 85% of the functionality of a virgin CB. Generally, the thermal weight loss (30% at 300–450 °C and 40% at ~470 °C) of the CBs varied little with the reprocessing cycles, reflecting their high thermal stability. The increased melting index (from 18.7 to 92.0 g (10 min)1) but decreased stress values (from 6.08 to 4.99 kgf mm2), strains (from 79.0 to 29.1 %), impact strength (from 144 to 14.7 J m1) and torque values (from 82 to 60 N m1) with reprocessing cycles suggest that the CBs undergo thermal/mechanical decomposition when reprocessing and become thereafter stiffer. Satisfactory modification of the 20 times reprocessed CB succeeded simply via adding ~30% (w/w) virgin PC and PBT. Adding styrene maleic anhydride and a chain extender failed to improve the stress values of reprocessed CBs, probably due to their weak interaction with the PC and PBT molecules.
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Jheng, Kai-Hong, and 鄭凱鴻. "Transparent Zirconia/polycarbonate nanocomposite." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2u46k9.
Full textAbstract:
碩士國立中央大學
化學工程與材料工程學系
105
In this study, we developed a high refractive index thermoplastic zirconia/polycarbonate nanocomposite useful in preparing optical components via injection molding. We have employed our alkaline hydrothermal method to synthesize cubic zirconia nanoparticles having 5 nm grain size. The surface of these zirconia nanoparticles was further modified with a carboxylic acid to form a stable dispersion in a nonpolar solvent. Sulfonated polycarbonate (SPC), produced by the sulfonation reaction of polycarbonate, was chosen as the coupling agent to make the zirconia compatible with the polycarbonate (PC) matrix. The carboxylic acid chelated zirconia nanocrystals formed a stable suspension in dichloromethane. Upon the adding of SPC, the carboxylic acid ligand was replaced by the SO 3 group of the SPC and the nanocrystals became transparently dispersible in the solvent. This approach is different from the use of PEAH as capping agent reported in the literature. The SPC capped zirconia obtained, after removing the carboxylic acid and solvent, could be cast or hot- pressed into a transparent piece about 100 µm thick. The maximum zirconia loading achieved was about 60wt%, leading to an index of 1.67 for the composite. We used the XRD and Raman spectroscopy to analysis the grain size and crystal phase of the zirconia nanoparticle, and the DLS to check the particle size distribution in nonpolar solvents. The Fourier transform infrared (FTIR) spectrometer was employed to investigate the chemical structure of the nanocomposite. The thermal stability of nanocomposite was studied by the thermogravimetric analysis and differential scanning calorimetry. The optical properties of nanocomposite were investigated by the UV-spectrum and Abbe refractometer. Our study showed that the degree of sulfonated influences the compatibility between zirconia and PC. More zirconia nanoparticles must be added to increase the refractive index of a nanocomposite, which requires a higher degree of sulfonation. However, excessive sulfonation decreases the thermal stability of the SPC, leading to yellowing upon thermal treatment during the hot press process. Therefore, there is an optimal degree of sulfonation that gives a balance between the thermal processability and refractive index.
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Chou, Dah-Cheng, and 周大成. "Polyblends of Polycarbonate and Polyamides." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/66200519423893171777.
Full textAbstract:
碩士國立交通大學
應用化學系
81
Both Polycarbonate (PC) and Polyamide (PA) are useful engineer- ing thermoplastics with excellent properties. The resulted blends have coarse domain morphology and phase debonding that indicate the poor compatibility between these two blending components and therefore poor mechanical properties. This dissertation includes two main parts. First we investigate the effect on mechanical properties of rubber distribution by adding core-shell type rubber with butadiene core and methyl methacrylate outer shell, with and without containing maleic anhydride reactive group. Since PMMA is more compatible to PC than to PA therefore the non-reactive rubber is in favor of PC phase. The maleic anhydride group in the reactive rubber particle can react with PA and form the PA- bonded rubber particles, which are more favorable residing in the PA phase than in PC phase.The results of mechanical properties show that the rubber residing in PC phase results in better toughening than residing in PA phase of the PC/PA blends.In the second part we try to use difunctional epoxy resin with phenoxy main chain to improve compatibility by reactive blending sequence.Results from morphological, mechanical and rheological properties show significant improvements essenti- ally on all compositions. We can futhur optimalize the physical properties of this blend by the combined use of epoxy resin and core-shell rubber.
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Liu, Fan-Shuan, and 劉凡瑄. "Recycling Polycarbonate Wastes into Polyurethanes." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/48790734528670142002.
Full textAbstract:
碩士國立中興大學
化學工程學系所
103
Green chemistries and processes have attracted tremendous attention nowadays in industrial research as well as academic studies to address chemical safety, atom economy along with environmental protection issues. As the result, the recycling technologies have occupied an important part of these green efforts by emphasizing waste management. This research explored the possibility of converting poly(bisphenol-A carbonate) (PC) by recycling it into new polyurethanes (PUs) in one-pot two-step process. The process took advantage of highly selective amine-carbonate reaction into carbamate formation, so that carbonate groups of PC could be utilized for making key urethane bonds. This basic chemistry has been studied in our recent non-isocyanate route to polyurethanes and non-phosgene isocyanate syntheses. In the first step of this recycling methodology, PC was digested by aliphatic diamines in anisole solution using 1,6-hexanediamine or 1,12-dodecanediamine to form N,N′-diphenyl-isopropylidene bisphenylene-carbamates (DP-biscarbamates) and bisphenol A as the interim products. Then, diisocyante such as hexamethylene diisocyanate, or 4, 4′-diphenylmethane diisocyanate were added into the digested mixtures for chain-extension to form PU. As the results, PC was completely turned into long-chained polyurethanes through this simple one-pot two-step process affording new PU materials. Differently from prior arts in PC-recycling, the carbonate groups of PC were fully utilized for making urethane bond while the rigid bis-phenyl structure of PC, BPA and DP-biscarbamates become the hard-segment components of the new polyurethane products. Thus, 100% of PC was utilized and incorporated into new PU product with minimum loss of weight.