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1
Adhikari, Kamal. "Effects of functionalized single walled carbon nanotubes on the processing and mechanical properties of laminated composites." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99617.
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Carbon Nanotubes are thought to have tremendous potential as reinforcements for the next generation of composite materials. In the past decade, the enhancing effects of the nanotubes on the mechanical, electrical as well as multi-functional properties of polymer composites have been reported. However, the same nanotubes/polymer composites investigated by different research groups, in many cases, do not show a good agreement with one another. The root cause of this variability is believed to lie in the processing methodology employed to prepare the composites. Before one can propose an ideal and systematic processing condition, it is imperative to have a fundamental understanding of the effect of these nanotubes on the processing of the nanotube-based composites. In this study, the effect of 0.2wt.% functionalized single walled carbon nanotubes on the various thermo mechanical and thermo chemical properties of aerospace grade epoxy was investigated. Namely, the thermal degradation, rheological behavior, cure kinetics as well as the thermal expansion behavior of the epoxy were addressed. In addition, the effect of the application small quantity of nanotube/epoxy composite film on the interlaminar shear strength (ILSS) of a conventional laminated carbon fibre/epoxy prepregs was also investigated. The characterization results show that the presence of the nanotubes has a very significant effect on some of the inherent physical and chemical properties of the epoxy. The presence of these nanotubes leads to a delay in the degradation temperature of the epoxy. The viscosity sees a seven-fold increase at room temperature and the resin also gels at a lower temperature in the presence of the nanotubes. At the same time, the total heat of reaction is also lowered on addition of the nanotubes. The mechanical test, however, shows that the addition of the nanotube/epoxy film does not affect the ILSS of the laminated carbon fibre/epoxy composite. This ILSS value is also found to be dependant on the controlled alignment of the nanotubes and the method of application of the film at the interfaces of the laminates. Finally, it was observed that the nanotubes, when used in such low contents, also had no effect on the thermo mechanical properties of the epoxy.Les nanotubes de carbone sont considérés comme ayant un potentielénorme pour assurer le rôle de renforts dans la prochaine génération de matériauxcomposites. Dans les décennies précédentes, les effets des nanotubes surl'amélioration des propriétés mécaniques, électriques et multi-fonctionnelles despolymères ont été révélés. Par contre, dans la plupart des cas, les études réaliséespar différents groupes de recherche et portant sur les mêmes composites faits depolymère renforcé de nanotubes ne présentent pas toutes des résultatscomparables. La cause majeure de cette variabilité est la méthodologie utiliséelors du procédé de fabrication de ces composites. Avant que quiconque ne suggèreune méthodologie idéale et systématique, il est impératif de comprendre les basesfondamentales de l'effet des nanotubes sur le procédé de fabrication. Dans cetterecherche, les effets des nanotubes de carbone à paroi simple sur les propriétésthermo mécaniques et thermo chimiques d'une résine époxy de gradeaéronautique ont été investigués. Les caractéristiques étudiées comprennent ladégradation thermique, le comportement rhéologique, la cinétique depolymérisation, ainsi que l'expansion thermique. L'effet de l'application d'unfilm de nanotube/époxy sur la résistance interlaminaire au cisaillement aégalement été étudié avec un préimprégné conventionel de fibre de carbone etd'époxy. Les résultats de caractérisation montrent que les nanotubes ont un effetsignificatif sur certaines propriétés physiques et chimiques inhérentes à l'époxy.La présence des nanotubes crée un délai dans la température de dégradation del'époxy. La viscosité de la résine est 7 fois plus élevée à la température de la pièceet sa température de gélification est inférieure. De plus, la chaleur totale deréaction est diminuée. Par contre, les tests mécaniques montrent que l'applicationd'un film de nanotube/époxy ne cause pas de changement dans la résistanceinterlaminaire au cisaillement d'un préimprégné de fibre de carbone et d'époxy.Par ailleurs, cette valeur de résistance est dépendante de l'alignement desnanotubes et de la méthode d'application du film sur les interfaces du laminé.Finalement, il a été observé que les nanotubes n'ont aucun effet sur les propriétésthermo mécaniques.
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Sharma, Bed P. "Effect of sonication on thermal, mechanical, and thermomechanical properties of epoxy resin /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1966551531&sid=3&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Sharma, Bed Prasad. "Effect of sonication on thermal, mechanical, and thermomechanical properties of epoxy resin." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/113.
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Epoxy resin is an important engineering material in many industries such as electronics, automotive, aerospace, etc not only because it is an excellent adhesive but also because the materials based on it provide outstanding mechanical, thermal, and electrical properties. Epoxy resin has been proved to be an excellent matrix material for the nanocomposites when including another phase such as inorganic nanofillers. The properties of a nanocomposite material, in general, are a hybrid between the properties of matrix material and the nanofillers. In this sense, the thermal, mechanical, and electrical properties of a nanocomposite may be affected by the corresponding properties of matrix material. When the sonication is used to disperse the nanofillers in the polymer matrix, with the dispersal of the nanofillers, there comes some modification in the matrix as well and it finally affects the properties of nanocomposites. In this regard, we attempted to study the thermal, mechanical, and dynamic properties of EPON 862 epoxy resin where ultrasonic processing was taken as the effect causing variable. Uncured epoxy was subjected to thermal behavior studies before and after ultrasonic treatment and the cured epoxies with amine hardener EPICURE 3223 (diethylenetriamine) after sonications were tested for mechanical and dynamic properties. We monitored the ultrasonic processing effect in fictive temperature, enthalpy, and specific heat capacity using differential scanning calorimetry. Fictive temperature decreased whereas enthalpy and specific heat capacity were found to increase with the increased ultrasonic processing time. Cured epoxy rectangular solid strips were used to study the mechanical and dynamic properties. Flexural strength at 3% strain value measured with Dillon universal testing machine under 3-point bending method was found to degrade with the ultrasonic processing. The storage modulus and damping properties were studied for the two samples sonicated for 60 minutes and 120 minutes. Our study showed that the 60 minutes sonicated sample has higher damping or loss modulus than 120 minutes sonicated sample.
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Gilbert, A. H. "Toughening tetrafunctional epoxy resins with thermoplastics." Thesis, Cranfield University, 1988. http://dspace.lib.cranfield.ac.uk/handle/1826/10722.
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The study described in this thesis examines how modification with different thermoplastics affects the structure and properties of a tetrafunctional epoxy re5ín_ Polyetherimide (PEI) is found to give the best improvement in fracture properties without loss in Youngs Modulus and the PEI/epoxy system is used as the basis for further study. The influences of PEI concentration, initial cure temperature, test temperature and the presence of a second thermoplastic additive, are investigated. The information provided gives insight into the likely mechanisms of toughening in tetrafunctional epoxy/thermoplastic blends. Flory-Huggins Lattice Theory is used to describe miscibility behaviour for a number of curing thermoplastic/epoxy blends and the predictions compared with the actual morphologies observed. Further, the sensitivity of the expected miscibility behaviour to fluctuations in Flory Huggins interaction parameter X12 and number-average molecular weight Mn of the thermoplastic, is considered. Dynamic mechanical analysis is used to monitor the changing viscoelastic properties of curing thermoplastic/epoxy blends, allowing investigation of the way different thermoplastics influence the state transformation profile of a curing epoxy resin.
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Thota, Phanindra. "Electrical Properties of Copper Doped Curcuminated Epoxy Resins." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1337031967.
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Ottemer, Xavier. "Effects of processing and environmental conditions on the properties of epoxy materials." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/18383.
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Hofmann, Klaus. "Synthesis, properties, and morphology of lignin based epoxy resins." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/37407.
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Star-like lignin-poly(propylene oxide) copolymers were prepared by chain-extending steam exploded lignins (tulipifera liriodendron) with propylene oxide and by subsequent endcapping with ethylene oxide. Epoxidation of these copolymers was carried out with epichlorohydrin at room temperature, using KOH as oxyanion forming reagent. The epoxidized compounds were fractionated by solvent precipitation to remove poly(alkylene oxide) homopolymers and to prepare fractions of narrow molecular weight distributions.
The epoxides were cross-linked with meta phenylene diamine yielding thermosets which were, depending on lignin content, either low modulus elastomers, or high modulus materials with considerable ductility. The modulus of elasticity was a strong and linear function of lignin content, whereby the highest value was 1100MPa (57% lignin).
The curing reaction was of nth-order type, whereby the reaction order changed from close to one at the beginning of the curing reaction to 2, once the reaction becomes diffusion controlled. Curing induced partial demixing of the lignin and poly(propylene oxide) phases which yielded a secondary structure where lignin rich domains in the order of 10 nm were interspersed in a matrix of lignin poor material. However, from TEM and ¹³C solid state cross-polarized NMR analyses it was evident that the domain structure was not that of a classical micro-phase separated copolymer with well defined phase boundaries, but rather had broad interphases. Additionally, the results of multifrequency dynamic mechanical thermal analysis showed that the lignin containing thermosets have very broad glass transition ranges which most likely were due to transitional phase inhomogeneities and provided these materials with good vibrational damping ability.Ph. D.
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Thitipoomdeja, Somkiat. "Factors influencing the properties of epoxy resins for composite applications." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/10852.
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The aim of the work reported here was to determine the influence of an amine curing agent, and postcure cycle on the mechanical and thermal properties of diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The results of this initial study were then used as the basis for selecting material to obtain optimum toughness in epoxy/glass fibre systems. These basic materials were further used to make comparisons with the properties of modified resin systems which contained commercial elastomers. Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analysis (DMTA), Fourier Transform Infrared Spectroscopy (FTIR), flexural and interlaminar shear tests, Instrumented Falling Weight Impact (IFWI), visual observation, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) were all used to investigate various properties and the structures which gave rise to them. The properties of cured products were found to be affected by the amounts of curing agent, curing times and temperatures, and the structure of the elastomers. Not surprisingly the maximum thermal and mechanical properties tended to be found in the stoichiometric (standard) mix systems. However, postcuring at higher than room temperature, which was used as the basic curing temperature, led to more conversion. This effect improved the thermal and mechanical properties of both the unmodified and modified resin systems. The maximum flexural strength of 104 MPa of the unreinforced resins was found in the stoichiometric mix ratio after postcure at 150°C for 4 hr. However, the maximum flexural modulus and glass transition temperature (Tg) were found after postcuring at the same temperature for 48 hr. This was believed to be due to increased crosslinking, but unfortunately the longer curing time led to degradation of the resins. In the systems modified with -20 phr of polyetheramine elastomers, the one modified with the lowest molecular weight (2000) was found to have the highest flexural strength (85.8 MPa) and modulus (2.5 GPa). The impact properties of all the composites with modified resin matrices were found to be higher than the unmodified resin matrix composites. The best impact properties were, however, obtained with the elastomer modifier with a molecular weight of 4000. The impact energy at maximum force increased from 11.9 to 16.4 J, and energy at failure increased from 18.7 to 21.6 J. This increase in impact properties was due to the increase in areas of phase separated elastomer particles over similar systems with lower molecular weight modifier.
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Balasubramani, Praveen Kumar. "Properties and Curing Kinetics of Epoxy Resins Cured by Chitosan." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1480328803855009.
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Greenfield, C. L. "The cure characteristics and physical properties of glycidyl-ether epoxy resins." Thesis, Brunel University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381904.
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Lau, C. H. "The synthesis and properties of epoxy resins of controlled crosslink density." Thesis, Brunel University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355209.
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Aziz, Roslan Abd. "The influence of thermohumid conditions on compression-after-impact properties of fibre-reinforced laminate materials." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/34052.
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Advance composite materials based mainly on epoxy resins are being used in increasing amounts in aerospace components due to their high strength:weight ratio. Such components have to survive in a range of temperature and humid environments in different parts of the world. The current generation of epoxy resins used in high performance fibre reinforced laminates absorb moisture from the atmosphere. Moisture absorption by the epoxy resins leads to a reduction in glass transition temperature and to a softening of the resin with a loss of resin stiffness and strength. In certain applications the components have to survive low impacts from dropped tools and rough handling during maintenance. Low energy impacts of this nature are considered potentially dangerous mainly because the damage might be left undetected. Even where no visible impact damage is observed at the surface, matrix cracking and interlaminar failure can occur, and the load carrying properties of the composite components is considerably reduced. A compression after impact (CAI) test is widely used in industry as the major screening parameters for materials selection. The aim of the work reported in this thesis was to determine the influence of thermohumid conditions on CAI properties and to assess the degradation behaviour of composite laminates under these thermohumid conditions.
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Simpson, Joycelyn Ovetta. "Modeling viscosity and ionic conductivity of epoxy resins using free volume concepts." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/10258.
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Ratnam, Mamatha D. "Correlation between the dielectric, rheological and structural properties of DGEBA-DDS epoxy." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/10203.
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Bolasodun, Babatunde. "Microwave effects on the curing, structure properties and decomposition of epoxy resins." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/microwave-effects-on-the-curing-structure-properties-and-decomposition-of-epoxy-resins(805aec6d-44e5-4a57-8f45-d61486a83bfc).html.
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Comparative studies were carried out on the curing kinetics, physical and mechanical properties of conventionally and microwave cured epoxy resins. Epoxy resins Araldite LY 5052 and DLS 772 were used for this study. 4 4' Diaminodiphenyl sulfone was used as a hardener in the preparation of both systems. Nuclear magnetic resonance and gel permeation chromatography were used to identify the chemical structure of the resins. Differential scanning calorimetry was used to monitor the curing kinetics of conventionally cured epoxy samples while a microwave heating calorimeter was used to monitor the curing kinetics of microwave cured epoxy samples 'in situ'. These studies were carried out under non-isothermal and isothermal conditions. For both conditions, there was a significant increase in the fractional conversion of the microwave cured samples compared to the conventionally cured samples. The curing reactions for samples cured using microwave heating took place over a smaller temperature range. Higher reaction rates were observed in the samples cured using microwave heating.There were some differences in the kinetic parameters of the non-isothermal curing reactions of samples cured using microwave and conventional heating. For the Araldite LY 5052 / 4 4' DDS epoxy system, the microwave cured samples had higher activation energy than conventionally cured samples, while for the Araldite DLS 772 / 4 4' DDS epoxy system, the microwave cured samples had lower activation energy. The activation energies of the microwave isothermal curing of both Araldite LY 5052 / 4 4' DDS and Araldite DLS 772 / 4 4'DDS epoxy systems were lower than the activation energies of the conventionally cured samples.Infrared spectroscopy showed that the curing reaction followed the same path during conventional and microwave heating. It also revealed that the reaction rate of the microwave cured samples was higher than the conventionally cured samples.For both epoxy systems, the microwave cured samples had a higher glass transition temperature (Tg) , higher cross-link density (v) and lower molecular weight between cross-links. These showed that the microwave cured samples had a more compact network structure than the conventionally cured samples, which is an indication of better mechanical properties.A microwave reaction system was used to successfully dissolve conventional and microwave cured samples of Araldite DLS 772 / 4 4' DDS epoxy system. The chemical structure of the decomposed product was determined.
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BERRY, NARA GUIDACCI. "MECHANICAL AND ADHESIVE PROPERTIES EVALUATION OF EPOXY RESINS BEFORE AND AFTER AGEING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6060@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOUm tipo de resina epoxídica (RE) foi modificada com polibutadieno líquido hidroxilado (PBLH) a partir da mistura física de ambos os componentes (EPH) ou a partir da obtenção de copolímeros em bloco da resina epoxídica com PBLH funcionalizado com grupos isocianato (EPI) e carboxila (EPA). Foi realizado um estudo do comportamento mecânico desses sistemas epoxídicos, após a cura com um endurecedor a base de aminas, antes e após envelhecimento. Também foram avaliadas as propriedades adesivas, antes e após envelhecimento, através de ensaios com juntas de topo e juntas sobrepostas simples fabricadas com esses adesivos e com substratos de aço. O estudo do envelhecimento abrangeu absorção de água a temperatura ambiente e envelhecimento térmico. Foi possível concluir que a condição de pós-cura estabelecida em um trabalho anterior não acarretou na densidade máxima de ligações cruzadas dos sistemas e isto afetou o comportamento dos mesmos após os envelhecimentos. Para as condições de cura e pós-cura aplicadas, a água, no período de tempo estudado, acarretou na plastificação dos sistemas, mas não afetou as propriedades adesivas das juntas fabricadas com os adesivos RE, EPA e EPI. Já o tratamento de envelhecimento térmico a 150oC por 7 dias acarretou na queda de algumas propriedades mecânicas, mas teve o efeito distinto de melhorar as propriedades adesivas das juntas fabricadas com EPI, EPH e EPA em relação à carga de ruptura, todavia resultando num aumento da rigidez efetiva dessas juntas.
A kind of epoxy resin was modified with hydroxyl- terminated polybutadiene (HTPB), using a physical blend of both components (EPH) or using a block copolymer of HTPB-RE. The block copolymers were prepared by reacting RE with isocyanate-funcionalized HTPB (EPI) or carboxyl- funcionalized HTPB (EPA). The cure agent was a blend of amines. A study of the mechanical behavior of these systems was carried out, before and after aging. Also the adhesive properties were evaluated, before and after aging, testing bonded joints (both butt and single-lap) manufactured with these adhesives and employing a steel adherent. This ageing study enclosed water absorption, at ambient temperature, and thermal aging. It can be concluded that the condition of post-cure, established in a previous work, did not promote the maximum crosslink density of the systems and this affected the behavior of these systems after aging. Considering the conditions of cure and post-cure and the period of time applied in this work, the water caused the plasticization of the systems, but it did not affect the adhesive properties of the joints manufactured with the adhesives RE, EPA and EPI. Considering the thermal aging treatment at 150oC during 7 days, it caused the decrease of some mechanical properties, but it had the distinct effect to improve the adhesive properties of the joints manufactured with EPI, EPH and EPA regarding the rupture load, however resulting in an increase of the joints stiffness.
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Bussi, Philippe Jacques. "Dynamic mechanical properties of epoxy resin/epoxidized rubber blends." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1060697951.
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Bilyeu, Bryan. "Characterization of Cure Kinetics and Physical Properties of a High Performance, Glass Fiber-Reinforced Epoxy Prepreg and a Novel Fluorine-Modified, Amine-Cured Commercial Epoxy." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4437/.
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Kinetic equation parameters for the curing reaction of a commercial glass fiber reinforced high performance epoxy prepreg composed of the tetrafunctional epoxy tetraglycidyl 4,4-diaminodiphenyl methane (TGDDM), the tetrafunctional amine curing agent 4,4'-diaminodiphenylsulfone (DDS) and an ionic initiator/accelerator, are determined by various thermal analysis techniques and the results compared. The reaction is monitored by heat generated determined by differential scanning calorimetry (DSC) and by high speed DSC when the reaction rate is high. The changes in physical properties indicating increasing conversion are followed by shifts in glass transition temperature determined by DSC, temperature-modulated DSC (TMDSC), step scan DSC and high speed DSC, thermomechanical (TMA) and dynamic mechanical (DMA) analysis and thermally stimulated depolarization (TSD). Changes in viscosity, also indicative of degree of conversion, are monitored by DMA. Thermal stability as a function of degree of cure is monitored by thermogravimetric analysis (TGA). The parameters of the general kinetic equations, including activation energy and rate constant, are explained and used to compare results of various techniques. The utilities of the kinetic descriptions are demonstrated in the construction of a useful time-temperature-transformation (TTT) diagram and a continuous heating transformation (CHT) diagram for rapid determination of processing parameters in the processing of prepregs. Shrinkage due to both resin consolidation and fiber rearrangement is measured as the linear expansion of the piston on a quartz dilatometry cell using TMA. The shrinkage of prepregs was determined to depend on the curing temperature, pressure applied and the fiber orientation. Chemical modification of an epoxy was done by mixing a fluorinated aromatic amine (aniline) with a standard aliphatic amine as a curing agent for a commercial Diglycidylether of Bisphenol-A (DGEBA) epoxy. The resulting cured network was tested for wear resistance using tribological techniques. Of the six anilines, 3-fluoroaniline and 4-fluoroaniline were determined to have lower wear than the unmodified epoxy, while the others showed much higher wear rates.
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Simpson, Joycelyn Ovetta. "Structure-dielectric property relationships for epoxy systems : a free volume analysis." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/10102.
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Gedeon, Sa'ad S. "The effect of gamma irradiation on the electrical properties of the epoxy resins." Thesis, University of Strathclyde, 1988. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21487.
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This thesis is concerned primarily with the curing of epoxy resin and the effect of gamma-irradiation on the electrical properties of epoxy resin systems. The particular systems examined were a diglycidyl ether of bisphenol A (DGEBA, Ciba Geigy MY750) epoxy resin cured using one of two hardeners. These were a hydroxyalkylated polyamine (Ciba Geigy HY956) and a dodecenyl-succinicanhydride (DDSA) with an accelerator of benzyldimethylamine. Different methods of examining the curing of the epoxy resin system have been carried out including differential scanning calorimetry (DSC), infrared spectroscopy (I.R.), dielectric measurements, volume resistivity measurements and thermally stimulated discharge current. The results of dielectric relaxation measurements obtained during the curing of the epoxy resin system were interpreted on the basis of a model considering the growing polymer molecules to be in solution, the solvent being the unreacted monomer and hardener. The investigation of the effect of gammairradiation on the electrical properties (conduction mechanism and dielectric behaviour) of the epoxy resin system was achieved by examining the electrical properties of the fully cured epoxy resin system before and after irradiation and the results compared. To establish the electrical properties of the fully cured epoxy resin system before and after irradiation, a series of experiments which provide information about the conduction mechanism, the dielectric properties, the infrared spectra (I.R.) and the glass transition temperature (Tg) obtained from (DSC) measurements were carried out. For the epoxy resin system MY750/HYS56, it was found that the D.C. conductivity, dissipation factor and capacitance values increase, whereas the glass transition temperature (Tg) and the activation energy, E, obtained from D.C. measurements decreased for the irradiated samples. Furthermore, a modification in the I.R. spectrum in the 1600 to 1800 cm⁻¹ range due to the formation of carbonyl groups (C = O) in the irradiated sample has been observed. However in the case of epoxy resin system MY750/DDSA, it was found that the dissipation factor and capacitance values decrease, whilst the glass transition temperature (Tg) and the activation energy obtained from dielectric measurements increased for the irradiated samples.
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Wang, Yunfei. "Correlation of dynamic dielectric properties to reaction kinetics and changing mechanical properties of epoxy resins during cure." W&M ScholarWorks, 1997. https://scholarworks.wm.edu/etd/1539623894.
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The principal objective of this paper is to describe how complex impedance, obtained from frequency dependent dielectric sensing technique, can be used as an effective diagnostic tool for in situ real-time investigation in the fabrication of thermoset structures.;Two epoxy systems (Pr500 from 3M and My720 from Ciba Geigy) with different functionality are characterized in terms of their dielectric, thermal, and rheological behavior. It is observed that there is a one to one relationship between Tg and conversion which is independent of cure temperature. The chemical kinetics of the reaction is satisfactorily described by an autocatalyzed reaction mechanism. The chemical rate constant has the usual Arrhenius form, whereas the diffusion rate constant is assumed to be given by a modified form of the Williams-Landel-Ferry (WLF) equation. The overall reaction rate constant is modeled by a combination of the chemical rate constant and the diffusion rate constant. The ability of the frequency dependent dielectric sensing technique to monitor the progress of curing reaction, build up in glass transition temperature, viscosity and to detect the time of occurrence of gel during thermoset cure are explored. The temperature dependence of the dielectric relaxation time, ionic conductivity and viscosity are described by the modified WLF equation. This approach provides a common framework for describing and comparing different related properties.
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Zitouni, Faiza. "Chemical modification of perfluoropolyether oligomers and effects on compatability and properties of epoxy resins." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/12452.
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The incorporation of fluorine in epoxy resins has been the focus of research for many years, aiming to reduce water absorption and to improve the degradation resistance in hot-moist environments. To this end resins have been synthesised from fluorinated monomers while crosslinking was induced by conventional hardeners. In the present work conventional diglycidyl ether of bisphenol A epoxy resins were modified by the addition of small amounts of perfluoropolyether oligomers containing functional groups at the chain ends. Compatibilisation of these oligomers in epoxy resins was achieved through end-capping and chain extension reactions. Such modifications of the fluoroligomers only affect marginally the viscosity of the resin mixture. Using hexahydrophthalic anhydride as the main hardener and through selective curing procedures the morphology of the crosslinked resins was controlled to. produce either transparent formulations, consisting essentially of an IPN monophase structure, or opaque systems containing precipitated spherical particles. Perfect adhesion is exhibited at the particle interface with the matrix, i.e. there was a complete absence of de bonding during fracture.
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Shah, Rakesh K. "Enhancements of Mechanical, Thermal Stability, and Tribological Properties by Addition of Functionalized Reduced Graphene Oxide in Epoxy." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699889/.
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The effects of octadecylamine-functionalized reduced graphene oxide (FRGO) on the frictional and wear properties of diglycidylether of bisphenol-A (DGEBA) epoxy are studied using a pin-on-disk tribometer. It was observed that the addition of FRGO significantly improves the tribological, mechanical, and thermal properties of epoxy matrix. Graphene oxide (GO) was functionalized with octadecylamine (ODA), and then reduction of oxygen-containing functional groups was carried out using hydrazine monohydrate. The Raman and x-ray photoelectron spectroscopy studies confirm significant reduction in oxygen-containing functional groups and formation of ODA functionalized reduced GO. The nanocomposites are prepared by adding 0.1, 0.2, 0.5 and 1.0 wt % of FRGO to the epoxy. The addition of FRGO increases by more than an order of magnitude the sliding distance during which the dynamic friction is ≤ 0.1. After this distance, the friction sharply increases to the range of 0.4 - 0.5. We explain the increase in sliding distance during which the friction is low by formation of a transfer film from the nanocomposite to the counterface. The wear rates in the low and high friction regimes are approximately 1.5 x 10-4 mm3/N·m and 5.5 x 10-4 mm3/N·m, respectively. The nanocomposites exhibit a 74 % increase in Young’s modulus with 0.5 wt. % of FRGO, and an increase in glass transition and thermal degradation temperatures.
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Puebla, Karina. "Effects of build orientation, aging, and pre-conditioning on mechanical properties for stereolithography-manufactured ASTM type I specimens using a design of experiments approach." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Briceno, Garcia Ruben Dario. "Crosslinking of ethylene copolymers from epoxy chemistry." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0037.
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La plupart des couches d'isolation de câbles pour la moyenne tension "MV" et haute tension "HV" sont fabriquées en polyéthylène réticulé (XLPE) par voie peroxyde. L'impact des sous-produits de réaction sur les propriétés et la nécessité d'une étape de dégazage au cours du processus sont les principaux problèmes liés à cette technologie. Cette étude se concentre sur le développement d'une méthode de réticulation alternative sans les problèmes liés aux sous-produits. Des copolymères d’éthylène/époxy ont été réticulés thermiquement en utilisant un agent aminoacide pour créer des liaisons covalentes entre les fonctions époxydes. L’influence de différents paramètres sur la cinétique de réaction tels que la température de réticulation, les proportions aminoacide/époxy, la taille des particules de l’aminoacide et la teneur en époxy dans les copolymères a été étudiée par techniques de caractérisation telles que : rhéologie dynamique, spectrométrie FTIR, microscopie à balayage électronique et calorimétrie différentielle. En outre, l'étude de la structure du réseau avant et pendant un vieillissement thermique a été effectuée par différentes techniques (mesures de gonflement, spectroscopie FTIR, propriétés de traction et thermoporosimétrie) sur deux types de réseaux : un pré-contraint et un autre non-contraint. Enfin, une caractérisation des propriétés électriques par spectroscopie diélectriques et mesures de claquage électrique a été faite. Les résultats concernant les cinétiques de réaction, les propriétés thermomécaniques et le comportement électrique ont montré que la formulation développée dans cette étude peut être utilisée pour une application de câbleMost of insulation layers of cables for medium voltage “MV” and high voltage “HV” applications are made of crosslinked polyethylene (XLPE) by peroxide technology. The impact of reaction by-products on properties and the consequential need of a degassing stage during the process are the main problems related to this technology. This study focuses on the development of an alternative crosslinking method without by-products issues. Epoxy-ethylene copolymers were thermally crosslinked by using an amino-acid agent to create covalent cross-links between epoxide functions. Influence of several parameters on kinetic reactions such as crosslinking temperature, amino acid/epoxy proportions, size particle of amino acid and epoxy content in copolymers were studied by characterization techniques such as: dynamic rheology, FTIR spectrometry, SEM microscopy and differential calorimetry. In addition, study of the network structure before and during a thermal aging was done on a pre-constrained and a non-constrained network by different techniques (swelling ratio measurement, FTIR spectroscopy, tensile properties and thermoporosimetry analysis). Finally, a characterization of electrical properties by dielectric spectroscopy and breakdown measurements was done. Results related to reaction kinetic, thermo-mechanical properties and electrical behavior have shown that the developed formulation can be used for cable application
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Michon, Marie-Laure. "Heterogeneous epoxy-amine networks from the dispersion of cross-linked polymer microparticles." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0018/document.
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Lors de cette étude, il a été étudié l'influence de l'ajout de microparticules de polymère réticulé (CPM) dans des formulations d'époxy-amine, sur la cinétique, la morphologie et les propriétés thermo-mécaniques des réseaux finaux obtenus. Tout d'abord, un protocole simple, robuste et bien contrôlé a été développé afin d’ obtenir une large gamme de taille de CPM, de Tg et de fonctionnalité amine. Ce protocole de polymérisation par précipitation, basé sur les phénomènes de séparation de phases, a également été appliqué à différentes compositions chimiques et différents monomères époxy hydrosolubles, ceci montrant les grandes possibilités de cette méthode. Une bonne interface entre les CPMs et la matrice a été recherchée en synthétisant les CPMs en excès de groupes amines. La quantification de ces groupes amines réactifs sur les CPMS était d'un grand intérêt et a donc été étudiée en profondeur. Le titrage des amines de surface a été réalisé en mettant au point un nouveau protocole qui a permis la quantification des amines primaires et secondaires sur les CPMs. Il a ensuite été mis en évidence que, bien que ces microparticules réticulées ne soient pas poreuses, des fonctions amines sont disponibles au cœur des particules et peuvent réagir avec d'autres molécules qui sont capables de diffuser dans la CPM. Il a été montré que lorsque les CPM ont été dispersées dans des mélanges d'époxy- amine, la diffusion des monomères dans le cœur de la CPM s'est produite mais différemment selon le procédé de dispersion. En effet, en utilisant le tétrahydrofurane comme solvant pour aider à la dispersion, la diffusion de la DGEBA est amplifiée et modifie les propriétés thermo-mécaniques du réseau final en modifiant le rapport stœchiométrique de la matrice. Le même phénomène a été observé mais moins amplifié lorsque les microparticules sont uniquement dispersées mécaniquement. En dispersant les CPMs dans l'amine qui est l'agent réticulant, on observe l'absorption complète de l'amine au coeur des CPMs, conduisant ainsi à la désorption de celle-ci dans une deuxième étape, permettant de créer le réseau. Ainsi, un comportement très complexe des CPM a été mis en évidence en présence des monomères et/ou solvant : le gonflement et les phénomènes de diffusion qui dépendent d'un certain nombre de paramètres tels que la température, la densité de réticulation des CPM, les paramètres de solubilité, etc. L'intensité du phénomène de diffusion conduit à une variété de comportements lorsque les CPMs sont ajoutées dans une formulation d'époxy-amine tels que: (a) une légère diminution du temps de gélification et l'augmentation de la conversion, (b) la modification de la température de transition vitreuse de la matriceThroughout this work, the influence of the addition of cross-linked polymer microparticles (CPMs) in epoxy-amine formulations on the kinetics, morphology and thermo-mechanical properties of the final networks have been investigated. First, an easy, robust and well-controlled protocol was developed to obtain a large range of CPM size, Tg and amine functionality. This protocol based on reaction induced phase separation via precipitation polymerization was also applied to different chemistries and water soluble epoxy pre-polymers showing the large possibilities of this method. The capacity of obtaining a good compatibility between the CPMs and the matrix was ensure by synthesizing the CPMs in excess of amino groups. The study of the remaining reactive amino groups on the CPMS was of great interest and therefore deeply investigated. The titration of the surface amine was performed by developing a new protocol that enabled the quantification of primary and secondary amines on CPMs. It was then highlighted that even though these cross-linked microparticles were not porous, amino groups are available into the core and can react with other molecules that are able to diffuse into the CPM core. It was shown that when CPMs were dispersed into epoxy-amine blends, the diffusion of monomers into the CPM core occurred but differently depending on the dispersion process. Indeed, using tetrahydrofuran as solvent to help for the dispersion increased the diffusion of DGEBA into the CPM core and changed the thermo-mechanical properties of the final network by modifying the stoichiometric ratio of the matrix. Same phenomenon was observed but less amplified when CPMs were mechanically dispersed in DGEBA. Regarding the dispersion of CPMs in the amine cross-linker, IPD, its complete absorption could be observed into the CPMs, leading then to the desorption of IPD to create the network. Thus, a very complex behavior of CPMs was highlighted in presence of monomers or/and solvent: swelling and diffusion phenomena that are dependent on a number of parameters such as temperature, CPM cross-link density, solubility parameters, etc. The intensity of those phenomena leads to a variety of behaviors when CPMs are added into an epoxy-amine formulation: (a) slight decrease of gel times and increase of conversion, (b) modification of glass transition temperature of the matrix
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Rosa, Bruno de Paula [UNESP]. "Caracterização mecânica e térmica de um polímero termorrígido modificado com fibra de buriti." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150094.
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Pensando na sustentabilidade, a introdução de fibras naturais em substituição às sintéticas no reforço de matrizes poliméricas, faz-se necessária entre outras coisas devido à preservação do meio ambiente, redução de custos, sem que comprometa a qualidade final do material. Esse projeto tem o objetivo de obter as características mecânicas e térmicas de materiais compósitos a base de resina epoxídica curada DGEBA/TETA com a adição de porcentagens específicas de fibras de buriti. A fibra escolhida foi o buriti, pela abundância no Mato Grosso do Sul, buscando um desenvolvimento sócio econômico para a região e a matriz escolhida foi a epóxi DGEBA/TETA por ser a resina mais utilizada no mundo. Foram utilizadas fibras com diâmetro de 0,17mm e comprimento de 30mm em porcentagens em massa de 1%,5%,10%,15% e 17,6% do total do compósito. A caracterização mecânica foi realizada através de ensaios de tração. Após a ruptura dos corpos de prova foi verificado com uso da Microscopia Eletrônica de Varredura (MEV),a formação de microvazios através dos ensaios de Termogravimetria (TGA) e Calorimetria Diferencial de Varredura (DSC) foram verificadas a degradação e temperatura de transição vítrea (Tg) dos compósitos. O compósito com a adição de 5% em massa de fibras apresentou um aumento de 11,98% (60,12 para 67,32 MPa) no limite de resistência a tração (LRT) e de 8,21% no módulo de elasticidade (E) (901,06 para 977,82 Mpa) em relação a resina pura, acima de 5% as propriedades permaneceram constantes. Já o Limite de Resistência à propagação de trincas (K1C) não apresentou alterações significativas ao se adicionar fibras a resina (permanecendo em torno de 1,19 MPa). Não houve alteração na transição vítrea, ficando em torno de 70ºC. Já o TGA verificou que a temperatura de degradação dos compósitos apresentou um valor intermediário entre a resina pura e a fibra pura.
Thinking about sustainability, the introduction of natural fibers instead of synthetic fibers in the reinforcement of polymer matrices, is necessary among other things due to the preservation of the environment, cost reduction without compromising the final quality of the material. This project aims to obtain the mechanical and thermal characteristics of composite materials based on cured DGEBA / TETA epoxy resin with the addition of specific percentages of buriti fibers. The fiber was buriti, due to the abundance in Mato Grosso do Sul, seeking a socioeconomic development for the region and the chosen matrix was the epoxy DGEBA / TETA as the most used resin in the world. Fibers with a diameter of 0.17mm and a length of 30mm were used in mass percentages of 1%, 5%, 10%, 15% and 17,6% of the total composite. The mechanical characterization was performed through tensile tests. After the rupture of the specimens was verified with the use of Scanning Electron Microscopy (SEM), the microgravity formation through the Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC) tests showed the degradation and glass transition temperature ( Tg) of the composites. The composite with the addition of 5% by mass of fibers presented an increase of 11.98% (60.12 to 67.32 MPa) at the tensile strength limit (LRT) and 8.21% in the modulus of elasticity ( E) (901.06 to 977.82 MPa) relative to pure resin, above 5% the properties remained constant. However, the Limit of Resistance to crack propagation (K1C) did not show significant changes when adding fibers to the resin (remaining around 1,19 MPa). There was no change in the glass transition, being around 70ºC. The TGA verified that the degradation temperature of the composites showed an intermediate value between the pure resin and the pure fiber.
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Rosa, Bruno de Paula. "Caracterização mecânica e térmica de um polímero termorrígido modificado com fibra de buriti /." Ilha Solteira, 2017. http://hdl.handle.net/11449/150094.
Full textAbstract:
Orientador: Newton Dias FilhoResumo: Pensando na sustentabilidade, a introdução de fibras naturais em substituição às sintéticas no reforço de matrizes poliméricas, faz-se necessária entre outras coisas devido à preservação do meio ambiente, redução de custos, sem que comprometa a qualidade final do material. Esse projeto tem o objetivo de obter as características mecânicas e térmicas de materiais compósitos a base de resina epoxídica curada DGEBA/TETA com a adição de porcentagens específicas de fibras de buriti. A fibra escolhida foi o buriti, pela abundância no Mato Grosso do Sul, buscando um desenvolvimento sócio econômico para a região e a matriz escolhida foi a epóxi DGEBA/TETA por ser a resina mais utilizada no mundo. Foram utilizadas fibras com diâmetro de 0,17mm e comprimento de 30mm em porcentagens em massa de 1%,5%,10%,15% e 17,6% do total do compósito. A caracterização mecânica foi realizada através de ensaios de tração. Após a ruptura dos corpos de prova foi verificado com uso da Microscopia Eletrônica de Varredura (MEV),a formação de microvazios através dos ensaios de Termogravimetria (TGA) e Calorimetria Diferencial de Varredura (DSC) foram verificadas a degradação e temperatura de transição vítrea (Tg) dos compósitos. O compósito com a adição de 5% em massa de fibras apresentou um aumento de 11,98% (60,12 para 67,32 MPa) no limite de resistência a tração (LRT) e de 8,21% no módulo de elasticidade (E) (901,06 para 977,82 Mpa) em relação a resina pura, acima de 5% as propriedades permaneceram consta... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Thinking about sustainability, the introduction of natural fibers instead of synthetic fibers in the reinforcement of polymer matrices, is necessary among other things due to the preservation of the environment, cost reduction without compromising the final quality of the material. This project aims to obtain the mechanical and thermal characteristics of composite materials based on cured DGEBA / TETA epoxy resin with the addition of specific percentages of buriti fibers. The fiber was buriti, due to the abundance in Mato Grosso do Sul, seeking a socioeconomic development for the region and the chosen matrix was the epoxy DGEBA / TETA as the most used resin in the world. Fibers with a diameter of 0.17mm and a length of 30mm were used in mass percentages of 1%, 5%, 10%, 15% and 17,6% of the total composite. The mechanical characterization was performed through tensile tests. After the rupture of the specimens was verified with the use of Scanning Electron Microscopy (SEM), the microgravity formation through the Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC) tests showed the degradation and glass transition temperature ( Tg) of the composites. The composite with the addition of 5% by mass of fibers presented an increase of 11.98% (60.12 to 67.32 MPa) at the tensile strength limit (LRT) and 8.21% in the modulus of elasticity ( E) (901.06 to 977.82 MPa) relative to pure resin, above 5% the properties remained constant. However, the Limit of Resistance to crack... (Complete abstract click electronic access below)
Mestre
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Dessertenne, Estelle. "Matériaux solide conducteur thermodurcissable : Application aux plaques bipolaires pour pile à combustible." Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00808869.
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Parmi les nouvelles technologies pour l'énergie inscrites dans un contexte de développement durable, les piles à combustible à membrane échangeuse de protons (PEMFC) présentent des aspects séduisants. Toutefois, pour rendre cette technologie compatible avec une application à grande échelle, elle doit répondre à des exigences strictes en termes de coût, performance, et durabilité. Alors que les plaques bipolaires métalliques sont pénalisées par leur résistance à la corrosion et celles en graphite par leurs propriétés mécaniques et leur coût (dû aux phases d'usinage des canaux), les plaques bipolaires composites apparaissent attrayantes en raison de leurs propriétés et performances et de leur coût. Cette thèse s'inscrit dans ce cadre, en proposant un matériau composite à matrice organique de type époxy et charges conductrices de graphite. L'objectif de notre étude consiste à mettre au point un matériau thermodurcissable à base d'une formulation époxyde solide (permettant de contrôler sa chimie et plus particulièrement sa réactivité) fortement chargée en graphite. Deux formulations différentes sont étudiées. La première est à base de prépolymère époxy appelé DGEBA et de dicyandiamide (DDA) comme durcisseur. L'autre formulation étudiée est constituée de DGEBA et de durcisseur : le 3,3',4,4'-benzophénone dianhydride tétracarboxylique (BTDA). Ces deux formulations ont la particularité d'être très réactives à haute température (180-200°C) caractérisées par des temps de gel très courts (plus petit que 1min) afin d'avoir un temps de cycle de réticulation court pour une industrialisation de la fabrication. De plus, ces mêmes matrices ont montré une bonne stabilité chimique à température ambiante ainsi qu'une bonne stabilité thermique du système réticulé compatible avec la température d'utilisation des piles en fonctionnement. Concernant les réseaux composites résultant de la polymérisation DGEBA/BTDA et DGEBA/DDA, le module au plateau caoutchoutique est dominé par le taux de charge qui est très élevé (85%), celui-ci est ainsi très proche d'un réseau à l'autre et reste supérieur à 1 GPa. Nous constatons une viscosité relativement élevée pour les systèmes fortement chargés, point à prendre en compte lors du procédé de transformation. Enfin, la dernière partie des travaux réalisés concerne l'étude de mélange constitué de la matrice thermodurcissable (DGEBA/DDA/urée) modifiée par un thermoplastique (PEI). L'originalité et l'intérêt de ce travail résident dans l'incorporation de charges conductrices afin que celles-ci puissent se disperser dans la phase continue ou co-continue époxyde-amine lors de la séparation de phase pour limiter la proportion de charges et ainsi la viscosité des systèmes chargés. L'autre intérêt est d'améliorer les propriétés de résistance à la rupture du réseau époxyde TD final grâce à la présence de la phase thermoplastique séparée.
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Škarabelová, Lenka. "Degradace epoxidových pryskyřic s různými plnivy slunečním zářením." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377078.
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This master’s thesis is focused on the study of chemical and physical properties of dielectric materials with main focus on epoxy resins. It includes possible processes that can influence the properties of epoxy resins, both processes that improve polymer properties and processes that cause material degradation. Next part of the thesis is a description of diagnostic methods suitable for measurement of basic electrical quantities of material and design of a suitable method for measuring properties of epoxy resins with different additives, influencing the samples by solar radiation. At the end, the work includes an experiment dedicated to the degradation of epoxy resins with various additives by solar radiation and the evaluation of the experiment.
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Matoušová, Klára. "Dielektrické vlastnosti epoxidových pryskyřic." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-402126.
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This diploma thesis deals with the fundamental properties of epoxide mixtures, as determining of these fundamental properties of epoxide mixtures could in the case of favorable results lead to diminishing the amount of defects in epoxide-embedded instrument transformers. As the influence of effects in the manufacturing process of transformers causing poor quality is very extensit, the biggest emphasis is laid capitally on the influence of the epoxide casting mixture composition. The thesis describes the manufacture technology including used methodics and materials. The compositions of epoxide resins and the mechanisms of their curing. Also, the definitions of fundamental properties of dielectric materials and the description of diagnostic methods used to relative permitivity, dissipation factor and inner resistivity are included. suitable casts of acquired samples were set and dried out within the experimental part, followed by measurement of fundamental electrical properties in temperature and frequency relations. Hereafter a comparison of individual samples and the evaluation of their electrical properties will be carried out.
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Horák, Luděk. "Analýza elektrických vlastností epoxidových pryskyřic s různými plnivy v teplotní a kmitočtové závislosti." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-376991.
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Presented master's thesis is focused on studying electroinsulating epoxy resin-based sealings. It describes the chemical composition, production, properties and measuring methods of basic electric quantities of these materials. The aim of the thesis is to compare several sets of samples of composite epoxy resins with different kinds of micro-ground siliceous sand as a filling. The temperature and frequency dependence of relative permittivity, dissipation factor and inner resistivity are measured for given samples.
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Reck, Bernhard. "Comportement mécanique anisotrope des composites stratifiés carbone/époxyde sous contraintes complexes : élasticité, endommagement, rupture." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10183.
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L'objet de ce travail est l'analyse experimentale et theorique du comportement mecanique anisotrope de trois types de stratifies composites carbone/epoxyde (unidirectionnel, croise et quasi-isotrope) dans les domaines de l'elasticite, des deformations irreversibles, de l'endommagement et de la rupture, sous sollicitations uniaxiales monotones et cycliques et sous contraintes complexes. L'instrumentation des eprouvettes par des jauges extensometriques a permis d'acceder aux differentes composantes du tenseur des deformations de green-lagrange. Les techniques experimentales tiennent compte des exigences particulieres des materiaux composites par l'utilisation du montage en doubles rotules ponctuelles en traction et du montage de boehler en compression simple et en compression sous pression de confinement. Les essais ont mis en evidence la forte anisotropie des differents stratifies. Pour les orientations hors-axes des stratifies unidirectionnel et croise, la deformation de distorsion joue un role important pour les modes de deformation et de rupture. Le plan du stratifie quasi-isotrope presente un comportement elastique isotrope et un comportement a la rupture anisotrope. A l'aide des essais cycliques, l'endommagement a ete evalue par les mesures des deformations irreversibles, des evolutions des modules directionnels et des variations relatives des modules directionnels en fonction des deformations irreversibles correspondantes. Sous etats de contraintes complexes, le critere de tsai et wu prevoit mal les resistances directionnelles des stratifies unidirectionnel et croise. La generalisation du critere de boehler, qui comporte trois branches correspondant a trois modes de rupture differents, est en tres bon accord avec les resultats experimentaux. Pour le stratifie quasi-isotrope, le critere de tsai et wu prevoit un comportement isotrope a la rupture, ce qui est en contradiction avec les donnees experimentales ; le critere de boehler prevoit correctement le comportement anisotrope a la rupture de ce stratifie
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Mathole, Alinah Phindiwe. "The effect of epoxidised soybean oil on the curing and (THERMO) mechanical properties of epoxy resins." 2012. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001351.
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M. Tech. Polymer Technology.Studies the effects of incorporating epoxidised soybean oil (ESO) in a standard bisphenol A-type epoxy resin (EP) cured by both amine and anhydride hardeners. The EP/ESO ratio was set for 100/0, 75/25, 50/50, 25/75 and 0/100 (wt./wt.). The investigations performed covered the curing, rheology (gelling), and thermomechanical analysis and thermogravimetric analysis of the sample produced.
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Peta, Neo Phyllis. "The effect of acrylated epoxidised soyabean oil on the curing and (THERMO) mechanical properties of vinyl ester resins." 2012. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001350.
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M. Tech. Polymer Technoliogy.Studies the basic curing, rheological and thermomechanical behaviours of hybrids composed of a VE resin and acrylated epoxidised soyabean oil (AESO). The hybrid systems were cured by free radical initiated radical copolymerisation with styrene. The prospective outcomes were: To find suitable initiators/accelerators for the VE/AESO hybrids which work within the entire composition range? To contribute to the selection of VE resins for AESO modification To establish the optimal quantity of AESO required obtaining the best cure characteristics, the most acceptable reduction in Tg, and stiffness as compared with the parent VE resin.
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Botha, Surene. "Effect of accelarator on the curing, chemorheology, thermal and mechanical properties of benzoxazine and benzoxazine epoxy resins." 2014. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001362.
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M. Tech. Engineering: Chemical.Aims to establish the cure kinetics of the thermosetting systems through the use of rheology and differential scanning calorimetry. Dynamic mechanical and thermal mechanical analyses will be used to ascertain the mechanical properties. The resistance to thermal degradation will be determined by thermogravimetric analysis.
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Chung, Yen-pin, and 鐘彥斌. "The physical properties of the siloxane-type epoxy resins blended with the commercial epoxy resins." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/76701393011428321352.
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碩士國立成功大學
化學工程學系
86
In this research, the siloxane-type epoxy resins were synthesized by hydrosily-lation reaction and the epoxide rings were attached on the side chain of the polysiloxanes, Their structures were characterized by the FT-IR and 1H-NMR.The siloxane-type epoxy resins were blended with the commercial epoxy resins and DICY was used as curing agent for the curing process. The reactivity of this blending system was determined by the DSC, and the physical properties of cured pieces were investigated by the TGA and the DMA.The TGA results show that the siloxane type epoxy resins are more stable at high temperature. The Tg obtained by DMA of the rigid epoxy network decrease when the amount of the siloxane-type epoxy resins increase because of the softness of -Si-O-Si- bonds.
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Chen, Weihsien, and 陳韋銜. "Properties study of ultraviolet curing epoxy resins." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/70631695335220854029.
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碩士東海大學
化學工程與材料工程學系
100
In this study, the photoinitiator, oligomers, and monomers with different proportions were mixed. The epoxy resins were cured by UV-A ultraviolet under a circulating nitrogen atmosphere. The completeness of curing was examined by using FTIR. Applying of TGA, TMA, and AFM for the initial degradation temperature, the glass transition temperature, the thermal expansion coefficient, and the average roughness helps to obtain the best curing condition. When the Irgacure 250 photoinitiator content was fixed at 2 wt. % and the percentage between oligomers and monomers changed, the initial degradation temperature, the glass transition temperature, the thermal expansion coefficient, and the average roughness of the resins with D-1217 monomer increased with increasing monomer percentage. Nevertheless, these variation trends were contrary to those of the samples with D-669 monomer. When the Chivacure 1176 photoinitiator content was fixed at 2 wt. % and the percentage between oligomers and monomers changed, no matter which monomer was used, the thermal expansion coefficient and the average roughness of the samples increased with increasing monomer percentage, but the initial degradation temperature of the samples decreased with increasing monomer percentage. The glass transition temperature of the resins with D-1217 monomer increased with increasing monomer percentage, but this variation trend was contrary to that of the samples with D-669 monomer. When the Irgacure 250 photoinitiator content changed and the amounts of oligomers and monomers were fixed, no matter which monomer was used, the initial degradation temperature and the average roughness of the samples increased with increasing photoinitiator percentage. The glass transition temperature and the thermal expansion coefficient of the resins with D-1217 monomer increased with increasing photoinitiator percentage, but these variation trends were contrary to those of the samples with D-669 monomer. When the Chivacure 1176 photoinitiator content changed and the amounts of oligomers and monomers were fixed, no matter which monomer was used, the glass transition temperature and the average roughness of the samples increased with increasing photoinitiator percentage, but the thermal expansion coefficient of the samples decreased with increasing photoinitiator percentage. The initial degradation temperature of the resins with D-1217 monomer increased with increasing photoinitiator percentage, but this variation trend was contrary to that of the samples with D-669 monomer.
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Fu, Shih-Chi, and 傅士奇. "Synthesis and Flame-Retardant Properties of Epoxy Resins." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/32749003399046851715.
Full textAbstract:
碩士國立臺灣大學
化學工程學系
85
In this experiment, the aryl-phosphonate is attached to the itaconic anhydride and used as flame-retardant curing agent (named DIA) for the epoxy resins. The epoxy resins, DER331 and DEN438, are cured with different proportion of DIA/HHPA and DIA/PA with 0.1phr BDMA as curing accelerator. The kinetics of DIA with epoxy are observed as auto- catalytic model. DMA is used to determine the variation of Tg with different proportion of DIA and TGA degradation curve in nitrogen and air are also investigated. The results indicates phosphorus will residue in the condensed phase(823K) and with increasing P content, the more char will be found. With addition of less than 1.5%P into the resin, it effectively raise the LOI of epoxy resins (DER331 series) to 30 from 19, providing excellent flame retardant property for the epoxy resins.
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Sun, Ming-Hsiao, and 孫明孝. "Curing and Properties of Phosphorus-Containing Epoxy Resins." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/97915185706298218976.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
86
The curing reaction of a bisphenol A type epoxy prepolymer(DER331)coupled with a curing agent containing phosphorus ( phenyl phosphorodiamidate ) was c onducted to obtain an epoxy resin containing phosphorus, PPDE. The kineticpara meters of the curing reaction were obtained by DSC analysis. The gel point in the curing reaction and the Tg changes of PPDE were observed by DMA analysis. The thermal degradation behavior of these phosphorus PPDE with different conte nts of phosphorus were examined by TGA analysis. The effectof the phosphorus c intent in PPDE on the LOI value was also studied.
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Yu, Su-Yun, and 尤素雲. "Synthesis and Properties of Phosphorus-containing Epoxy Resins." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/70331542246381829043.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
85
Both novel phosphorus-containing oxiranes in main chain (GPPDCO) and side chain (GDPPCO) were synthesized by glycidol reacted with phenyl phosphonic dichloride and diphenyl phosphonic chloride. These phosphorius-containing epoxy mixed with DER331 and cured with diethylene triamine (DETA) These systems were studied by differential scanning calorimeter (DSC),and kinetic parameters were determined. Furthermore, the thermal degradation and flame resistance behaviors of the cured epoxy resins were studied by thermogram (TGA) analysis method, and the limit of oxygen index analysis (LOI).According to the results of DSC analysis, the activation energies of the curing reactions of GPPDCO and GDPPCO are 51.2 KJ/mol and 45 KJ/mol ,respectively, which are lower than DER331,and decrease with increasing of the content of phosphorus. Both of the curing reactions of GPPDCO and GDPPCO are about first order. The thermal behaviors of two types epoxy resins showed lower degradation temperature than DER331,but the thermal degradation energy calculated by Ozawa's method were higher than DER331. The LOI value of phosphorus- containing oxiranes in main chain (GPPDCO) was 31.The high char yields (at 550℃) as well as high LOI values of the DER331based resin confirmed the effectiveness of GPPDCO resins, but an opposite result of GDPPCO resins. Key Words: epoxy resin, phosphorus, cure, decomposition, LOI ,flame resistance
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Yang, Ai-Chi, and 楊艾琪. "Preparation and Properties of Polyphenylene Oxide Based Epoxy Resins." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/02670967486192305552.
Full textAbstract:
碩士國立高雄應用科技大學
化學工程與材料工程系
97
Polyphenylene oxide (PPO) are suitable as a material for the printed circuit boards used in the electronic devices that utilize broadband, owing to their high glass transition temperature (Tg ) and favorable high frequency characteristics for example in dielectric constant and dielectric loss. However, PPO resins were not so far sufficiently high in heat resistance and dimensional stability. In addition, these PPO resins carry the disadvantage that they generally have a high melting point, and the use of such a PPO resin for production of prepregs for ordinary multilayer printed circuit boards often resulted in increases in melt viscosity of the prepreg, causing processing defects. Therefore, there is need a low molecular weight PPO (LPPO) and to modify it into a thermosetting resin so as to increase the heat resistance properties and to improve processability. The goal of this research is focused on the preparation of polyphenylene oxide based epoxy resin composition, which can be used in preparing prepregs and copper-clad laminates for high frequency printed circuit boards. Low molecular weight polyphenylene oxides (LPPO) can be synthesized by the oxidatively coupling a bifunctional phenol and a monofunctional phenol compound in the presence of cupric chloride and an amine. The structure of synthesized LPPOs will be confirmed by Fourier transform infrared spectroscopy (FTIR), Gel-Permeation Chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR). Later utilized OH of polyphenyl ether and epichlorohydrin to epoxidation in base-catalyzed condition, it can get LPPO-based epoxy resin (EPPO). EPPO cured with cyanate ester (BADCy), and their thermal curing behavior of EPPO was studied by differential scanning calorimetry (DSC). The properties of cured EPPO/BADCy were studied by dynamic mechanical analysis (DMA), dielectric analysis (DEA), thermal gravimetric analysis (TGA) and moisture absorption. The results show that cured EPPO possess a low dielectric constant, high Tg, low water absorption, and good retention of mechanical properties. The dielectric constant and moisture absorption of resulting cured epoxy resins decreased with the increasing of EPPO contents and decreasing of molecular weight. Reveal the low molecular weight EPPO has good promotion to signal velocity and transmit losses to signal pace which of the high-frequency printed circuit board, and have more ideal improvement to the resistance of moisture absorption. In thermal stability properties, the cured epoxy resins of higher molecular weight has better heat-resisting properties and also can promote char yield Various contents of EPPO were added into o-Crcsol Novolac epoxy resin and Bismaleimide-Triazine (BT) resin, respectively. The thermal curing behaviors of thermocurable epoxy resin and thermocurable BT resin were investigated, and their cured network’s physical properties were also investigated. The results indicate that EPPO effectively reduce the dielectric constant and moisture absorption both of cured epoxy resin and BT resin. The thermal stability properties of cured epoxy resins were increased with the increasing of EPPO contents, whereas the glass transition temperature slightly decreased. Then the thermal stability properties of BT resins were increased with the decreasing of EPPO contents, whereas the glass transition temperature slightly increased.The cured green materials prepared therefrom will be highly solder resistant, solvent resistant and also have excellent dielectric properties. The use of this resin composition will be environmentally friendly and demand on technology.
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Wei, Wen-Lung, and 魏文龍. "Using diethylphosphite as a thermally latent curing agent for epoxy resins and the properties of the cured epoxy resins." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/22617145369955217700.
Full textAbstract:
碩士中原大學
化學工程研究所
91
Abstract Diethylphosphite (DEP) can be used as a thermally latent curing agent for epoxy resins by means of the formation of phosphonic acid active groups through the de-ethanol reaction of DEP. The mechanism and activation energy of the curing reaction and the thermally latent characteristics of DEP on curing epoxy resins were demonstrated with 1H NMR, pyrolysis-GC/MS, and DSC measurements. The cured epoxy resins exhibited good thermal stability over 300 ℃ and improved flame retardance alone with the introduction of phosphorus element from DEP curing agent. Therefore, this commercial available DEP compound was potentially used as thermally latent curing agent and flame retardant for epoxy resins. While a maleimide-epoxy compound (4-maleimido phenylglycidyl ether, MIE) was cured with DEP, the resulting resins showed thermal stability over 350 ℃. Extremely high flame retardance was also observed with the DEP-MIE cured resins owing to the P-N synergistic effect on flame retardance. The properties of the DEP cured epoxy resins could be further leveled up with incorporating nanoscale colloidal silica to form epoxy-silica nanocomposites. Nanoscale silica also showed synergistic effect with phosphorus on improving the flame retardance of the cured epoxy resins. Moreover, the kinetics of the thermal degradation of the DEP cured epoxy resins were also investigated with thermogravimetric analysis.
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Fu, YaChing, and 傅雅卿. "Synthesis and Physical Properties of High Refractive Index Epoxy Resins." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/55051870889808575656.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
90
Epoxy resins with high refractive indices could be potentially useful as optical adhesives for optoelectronics and electro-optical equipment assemblies. However, the refractive indices of epoxy resins are generally between 1.50~1.56. Thus the goal of this study is to develop high refractive index (>1.60) epoxy resin system and study the effects of chemical structures on their optical as well thermal properties. Molecular design approach is applied to reach this goal by implement of rigid rod moieties, such as biphenol group (BP epoxy), naphthalene group (HP epoxy), and azomethine linkage group (AM epoxy), or heavy elements, such as bromine atom (BEB350 epoxy), into the epoxy structures. Characterizations of optical properties including refractive indices and ultraviolet/visible spectrum transmission were undertaken. The epoxy resins containing rigid rod structure does exhibit better thermal properties and higher refractive index than those containing flexible structure. Thermal properties of these epoxy resins were also studied by Thermogravimetric Analyzer (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analyzer (DMA), and Thermal Mechanical Analyzer (TMA) in order to investigate the effects of changes of chemical structures.
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Huang, Jien-Ruei, and 黃建睿. "Study Curing Kinetic and Properties of Liquid Crystalline Epoxy Resins." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/06657148206998742150.
Full textAbstract:
碩士國立臺灣大學
高分子科學與工程學研究所
95
The goal of this research focuses on the kinetic and material properties of the epoxy resin systems and the curing agents selected. The epoxy resins studied in the research is self-synthesized liquid crystalline epoxy resins (BP, AM) and commercial non-liquid crystalline epoxy resins (TMBP, DGEBA). One of the curing agents, DDS, has a more rigid molecular structure. The other curing agents, DDE, has softer molecular structure. From the kinetic study, we can find that Epoxy/DDE has lower activation energy and react faster than Epoxy/DDS. But Epoxy/DDE systems possess poorer mechanical properties when made into bulk materials. The curing agent, DDS, possess a more rigid molecular structure. Hence, Epoxy/DDS results in better mechanical properties and is suitable to be used in aerospace applications. We apply autocatalytic model to described the reaction of epoxy/amine systems. The parameters of the model can be obtained through DSC measurement and be used to adjust the curing time and temperature for the reaction. We have found the prediction of model is better fitting experimental results as the reaction temperature increases. Modifying the curing process according to the result of the kinetic study, we are able to reduce the curing time designed by Huang in 2001. According to the experimental results, we found that the mechanical properties of Epoxy/DDS are better than that of Epoxy/DDE and the mechanical properties of liquid crystalline epoxy resin are better than that of non-liquid crystalline epoxy resin. As a result, we can view the alignment of the liquid crystal as a self-reinforced effect which can increase the composite’s mechanical properties without adding extra fibers.
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Chuang, Chih-Min, and 莊智閔. "Physical Properties of Cyanate Ester Cured Liquid Crystalline Epoxy Resins." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/68737568329979486292.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
88
This research project is to investigate the curing properties of main chain rigid-rod epoxy resin cured by cyanate ester. Rigid rod resin with liquid crystalline properties: azomethine epoxy resin (AM), biphenol epoxy resin (BP), rigid rod resin of tetramethyl biphenyl epoxy resin (TMBP), and conventional epoxy resin of diglycidyl ether of bisphenol A (DGEBA), were cured by 2,2’-bis(4-cyanatophenyl) propane (B10) with the ratio of 1:0.5, 1:1, and 1:2 respectively. The curing conditions were studied by using differential scanning calorimetry (DSC). The cured samples were examined by thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA) and thermomechanical analyzer (TMA). The TGA results show that the ratio of cyanate ester increases, the char yield will increase at 450℃. At the same ratio, AM has the highest residual weight, and TMBP has the highest thermal decomposition temperature. When the ratio of cyanate ester increases, the glass transition temperature of cured resin increases. At the same ratio, AM exhibits the highest glass transition temperature, TMBP and DGEBA are in the second and third place respectively. Regardless the ratio of cyanate ester, the effects on the value of thermal expansion coefficient are not obvious expect DGEBA. The dielectric constant of cyanate ester cured epoxies decreases when the ratio of cyanate ester increase. The improvement in thermal and dielectric properties for high cyanate ester ratio sample can be explained by the formation of high concentration of crosslinked triazine structure. Cyanate ester cured rigid rod epoxies exhibit high temperature resistance and low dielectric constant. They are useful in the application of high density printed wiring boards, high performance integrated circuited encapsulation compounds and aerospace composites.
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Hsu, Wei-hsun, and 徐偉勛. "Crosslinking Reactions and Surface Properties of Interpenetrating Networked Epoxy Resins." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/58392950191414226649.
Full textAbstract:
碩士國立高雄大學
化學工程及材料工程學系碩士班
101
In this study, two epoxy resins with different crosslinking reaction rates were chosen for the preparations of interpenetrating networked polymers (IPN) and were investigated on the dependence of their surface properties on compositions of epoxy resins using FTIR, DSC, and contact angle analyzer for chracterizations. The epoxy resins included diglycidyl ether of bisphenol A (DGEBA) and methyl-3,4-epoxycyclohexyl-carboxylate (MECC), both using methylhexahydrophthalic anhydride (MHHPA) as the curing agent. The compositions included DGEBA/MECC/MHHPA 100/0/100, 75/25/100, 50/50/100, 25/75/100, and 0/100/100, crosslinking at 110 ℃, 130 ℃, and 150 ℃ for 30 min. FTIR spectra confirmed the occurrence of crosslinking reactions and formation of IPN structures. DSC data found that the crosslinking reactions were exothermic and the exothermic peaks shifted to higher temperatures with higher DGEBA/MECC weight ratios, indicating that the reaction rate of MECC was higher than that of DGEBA. The measurements of water contact angles of the cured IPN found that the contact angles at top and bottom of the cured samples both decreased with decreasing DGEBA/MECC weight ratios, an indication that higher contents of MECC in composition would give more hydrophilic surface properties and might lead to higher adhesive strengths.
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Chen, Kai-Chi, and 陳凱琪. "The Curing Properties of Main Chain Rigid-rod Epoxy Resins." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/26244536079355687512.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
86
This research project is to investigate the curing properties of main chai n rigid-rod epoxy resins. Rigid rod resins with liquid crystalline properties: azomethine epoxy resin (AM), biphenol epoxy resin (BP), rigid rod resin of te tramethyl biphenyl epoxy resin (TMBP), and conventional epoxy resin of diglyci dyl ether of bisphenol A (DGEBA) were cured by methyl cyclohexane 1,2-dicarbox ylic anhydride (MCHDA), sulfanilamide (SAA) respectively. The curing condition s were studied by using differential scanning calorimeter (DSC). The cured sam ples were examined by thermogravimetric analyzer (TGA), dynamic mechanical ana lyzer (DMA) and thermomechanical analysis (TMA). The TGA results show that liquid crystalline epoxy resin (BP, AM) exhibit a slower thermal decomposition rate and a higher char yield at 450℃ than that of other resins. The BP/SAA s ystem exhibited the highest glass transition temperature (Tg=218.5℃) and the lowest thermal expansion coefficient (α1=20.76μm/m℃) among the tested sampl es. A liquid crystal morphology still remained in the cured BP/SAA according to X-ray diffraction. Overall, the cured liquid crystalline epoxies have impro ved thermal propertiesover conventional bisphenol A epoxy and tetramethyl subs tituted biphenyl epoxy.Key words: Epoxy Resin, rigid-rod, curing, CTE, thermal degradable, liquid crystalline epoxy
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Lin, Ching Hsuan, and 林慶炫. "Synthesis, characterization and properties of phosphorus-containing polyesters and epoxy resins." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/77865523033293306384.
Full textAbstract:
博士國立成功大學
化學工程學系
87
A series of phosphorus-containing polymers, including polyesters and epoxy resins, were synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)。 Polyester section: A phosphorus-containing aromatic diol (DOPOBQ) was synthesized from DOPO and para-benzoquinone and then reacted with aromatic acid chloride to form a series of phosphorus-containing polyarylates. DOPOBQ also reacted with ethylene carbonate to form a phosphorus-containing aliphatic diol (DOPOBQE) and a series of phosphorus-containing PEN or PBN copolyesters were obtained from the reaction of DOPOBQE and bis(hydroxyethyl) naphthalate or bis(hydroxybutyl) naphthalate. Among these polyesters, we investigated the crystallization and multiple melting point phenomena of PBN copolyesters. We also investigated the blending and transesterification of PEN copolyester/PBN system. Epoxy section: A series of phosphorus containing advanced epoxy resins were obtained from DOPOBQ and DGEBA. However, the advanced epoxy resins is not quite soluble in acetone, which hindered their application in electrical laminate. Thus, DOPO was directly reacted with CNE or DGEBA to form a series of epoxy resins which are soluble in acetone. After curing, they exhibited high glass transition and high flame retardancy. The structures of synthesized monomers were confirmed by IR, Mass, EA, NMR and DSC and the properties of synthesized polymers were checked by DSC，TGA，DMA，UL-94 and LOI measurements. The data implied that these phosphorus-containing polymers exhibit good thermal stability and good flame retardancy.
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Wang, Wen Hsien, and 王文憲. "The Effects of Additives on Properties of Epoxy Resins and Their." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/46098135759679672904.
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