Dissertations / Theses on the topic 'Polystyre'

The diploma thesis deals with radical bulk polymerization of styrene. Recent knowledges about mono- and multifunctional initiators of radical polymerization and coordination polymerization of styrene with metalocene initiators are summarized in theoretical part. Experimental part of diploma thesis is focused on relationship between polymerization conditions and conversion, molecular mass and distribution of molecular mass. Experiments carried out with monofunctional initiators (dibenzoylperoxide, dilauroylperoxide, tert-butylperbenzoate) and with bifunctional initiators (Luperox 101 and Luperox 256). Polymerizations took place at temperatures from 80 to 134 °C, reaction time was from 1 to 24 hours, and pressure was 100 and 500 kPa. Conversion of monomer was determined by gravimetry and infrared spectroscopy. Molecular mass and indexes of polydisperzity were measured by gel permeation chromatography in solutions of polystyrene with tetrahydrofurane at temperature 23 °C.

The topic of my thesis are menhirs. Specifically, the largest Czech menhir known as the Stone Shepherd (3200 cm). The aim of this work was to transfer the exact shape and size of this megalith and materialize it here in Brno. This goal required the use of many procedures. At the beginning there was a photo shoot, then a 3D program, 3D program editing, and slicing into contour lines. Then I projected the menhir on a wall in real size and traced it to polystyrene boards. The next step was to cut out all 104 plates on a band saw and I could go to gluing and folding the whole object. The final step was to paint the object in white. The result is a simple and clean polystyrene object. I did not cover the contour lines - I present the object in the most direct form possible. The styrofoam megalith, despite its size, is a sculpture in the interior. Ideally, I would create an installation that would create a separate, isolated space for the object.

Les comportements photochimiques du polystyrène, du polyacrylonitrile et du poly(styrene-co-acrylonitrile), sous irradiations a courte longueur d'onde (egale a 254 nm) et a grandes longueurs d'onde (superieures ou egales a 300 nm), ont été étudiés. Différentes techniques d'identification des photoproduits formes lors de l'irradiation des polymères sous forme de films solides ont été utilisées: spectroscopies irtf et uv-visible, chromatographie hplc. D'autres méthodes, permettant de transformer spécifiquement les photoproduits, ont été associées a ces techniques analytiques: traitements chimiques (sf#4,nh#3,hcl,ch#3oh,h#2o) et traitements physiques (photolyse, thermolyse et thermooxydation). L'identification des photoproduits et la caractérisation de leur stabilité thermique et photochimique ont permis d'établir le mécanisme de photooxydation de chacun des trois polymères étudiés

Lors de ce travail, de fins films de polystyrène ont été déposés dans la post-décharge d’une torche plasma atmosphérique commerciale, mais aussi dans la décharge d’une DBD (Décharge à Barrière Diélectrique), conçue et développée par nos soins au laboratoire. Une DBD est un procédé permettant d’obtenir des plasmas froids à pression atmosphérique.

Nos résultats ont montré que la DBD permettait d’obtenir des films de polystyrène de meilleure qualité (degré d’oxydation moindre…) qu’avec la torche commerciale en raison de l’atmosphère contrôlée de l’enceinte DBD. Les films sont déposés en présence d’un gaz porteur (Ar ou He dans la DBD). Nous avons pu mettre en évidence l’influence de la nature de ce gaz porteur sur la structure des films (degré de branchement, et de réticulation des films et de préservation des cycles aromatiques de la molécule de départ).

Les dépôts de polystyrène sulfoné ont été synthétisés dans la DBD en une seule étape, par « copolymérisation » de deux précurseurs (styrène et acide trifluorométhane sulfonique) injectés simultanément dans la décharge. Ces membranes pourraient servir d’électrolyte dans les piles à combustibles miniaturisées de type PEMFC (« Polymer Electrolyte Membrane Fuel Cell »), utilisant de l’hydrogène ou du méthanol et ce pour des applications portables.

L’acide trifluorométhane sulfonique permet le greffage de groupements sulfoniques échangeurs d’ions (nécessaires pour la conductivité de la membrane) sur le squelette de polystyrène.

La complémentarité des différentes techniques spectroscopiques utilisées -Spectroscopie des Photoélectrons X (XPS), Infra-Rouge à Transformée de Fourier (FTIR), Spectroscopie des Ions Secondaires (SIMS) statique et dynamique- ont montré que les groupements acides sulfoniques (bien préservés dans la décharge à pression sub-atmosphérique) étaient bien greffés dans la matrice de polystyrène, et ce sur toute l’épaisseur de la membrane. L’influence des paramètres (température de l’acide, tension appliquée entre les électrodes, nature du gaz porteur…) sur la quantité de groupements ionisables greffés, sur la vitesse de dépôt et aussi sur la morphologie des films a été étudiée respectivement par XPS et par microscopie.

En plus des dépôts sur substrats usuels (Si, acier…) utilisés pour les caractérisations chimiques, nous avons synthétisé les films directement sur des électrodes de carbone enrichies en platine.

Nous avons déposé le catalyseur à partir d’une solution colloïdale de platine nébulisée dans la post-décharge d’une torche plasma atmosphérique sur des couches de carbones poreuse et sur du carbone vitreux (utilisé comme modèle pour le profilage par SIMS dynamique) dans différentes configurations et ce pour différents paramètres afin de constituer des électrodes servant de substrat pour l’adhésion de la membrane-plasma pour des perspectives d’assemblage membrane-électrodes pour PAC. /

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Doctorat en Sciences
info:eu-repo/semantics/nonPublished

A series of four novel halosilylsubstitued monocyclopentadienyl titanium complexes; [Si(CH3)2FCp]TiCl3 – FSiTTC, [Si(CH3)F2Cp]TiCl3 F2SiTTC, [Si(CH3)Cl2Cp]TiCl3 - Cl2SiTTC, [Si(CH3)2ClCp]TiCl3 - ClSiTTC was tested as catalytic precursors for polymerization of styrene in toluene. The maximum polymerization activity was achieved after polymerization period of 20 minutes. Activity decreased in order FSiTTC/MAO > F2SiTTC/MAO > Cl2SiTTC/MAO > ClSiTTC /MAO. Prepared polystyrenes were characterized using 13C NMR spectroscopy and DSC analysis. Syndiotacticity index of obtained PSs was determined by means of Soxhlet extraction with butan-2-one as solvent. Syndiotacticity indexes of PSs obtained by investigated catalysts possessed higher values then those obtained by standard catalysts (CpTiCl3 a Cp*TiCl3) at comparable polymerization conditions.

Cette thèse a pour objet de développer une nouvelle méthodologie pour valoriser les poudrettes de pneus usagés (PPU). Celles-ci résultent du broyage de la partie caoutchoutique des pneus usagés qui conserve l’excellente élasticité. L’idée est de profiter de leur élasticité pour renforcer la résistance au choc des polymères fragiles tels que le polystyrène (PS) en y incorporant les PPU. Cependant, la réalisation de cette idée a besoin de relever deux défis majeurs : (1) les PPU commerciales ont typiquement des diamètres de l’ordre de plusieurs centaines de micromètres. Or elles doivent être deux ordres de grandeur plus petits en taille pour pouvoir améliorer la résistance au choc des polymères fragiles. (2) L’adhésion interfaciale entre les polymères et les PPU est mauvaise et constitue donc des défauts mécaniques du matériau. Ces deux défis sont liés à la nature même des PPU qui sont intrinsèquement des réseaux réticulés chimiquement. Cette thèse choisit le PS pour représenter les polymères fragiles. La méthodologie visant à renforcer sa résistance au choc est de polymériser le styrène par voie radicalaire au sein des PPU. Cette polymérisation forme à la fois des chaines en PS libres et des greffons en PS liés chimiquement aux mailles du réseau des PPU. Les inclusions des chaines en PS libres facilitent la dispersion des PPU en taille plus petite lorsqu’une action mécanique leur est appliquée lors de l’extrusion par exemple. La formation des greffons en PS sur les mailles du réseau des PPU renforce l’adhésion interfaciale entre le PS et les PPU. Cette thèse a développé un modèle complet permettant de décrire la cinétique de polymérisation radicalaire du PS libre et celle des greffons en PS liés aux mailles du réseau des PPU. Elle l’a validé par un plan d’expériences judicieux
This thesis aims to develop a novel approach to value ground tire rubber (GTR). The latter results from grounding of the rubber part of used tires which retains excellent elasticity. The idea is to take the advantage of its elasticity to toughen brittle polymers such as polystyrene (PS) upon incorporating GTR into them. However, two challenges have to be overcome to realize this idea. (1) Commercial GTR is typically in the form of particles of a few hundreds of micrometers in diameter. However, it has to be at least one to two orders of magnitude smaller when incorporated in a brittle polymer so as to be able to improve its impact resistance. (2) The interfacial adhesion between the polymer and GTR is weak. These two challenges are related to the intrinsic nature of the GTR which is chemically cross-linked. This thesis chooses PS to represent brittle polymers. The approach aiming at toughening it is to polymerize styrene in a free radical manner inside cross-linked GTR particles. This leads to the formation of both free PS and PS that is grafted onto the GTR, denoted as grafted PS. The inclusions of the free PS inside the GTR particles help break them down by mechanical shear in a screw extruder for example and the formation of grafted PS improves the interfacial adhesion between the PS and the GTR. This thesis has developed a comprehensive kinetic model for the polymerization of free PS and that of grafted PS. This model is validated by experimental designs

Le moussage du polypropylène (PP) et du polystyrène (PS) par le scCO2 est étudié de manière systématique avec l’accent sur la relation entre le procédé, la microstructure et les propriétés mécaniques. La première partie de cette thèse porte sur l’amélioration de la résistance au choc du PP par cristallisation induite par le scCO2. Dans un deuxième temps, le PP fortement orienté avec des structures shish-kebab et sphérolite est utilisé pour étudier l’influence de la structure cristalline sur la nucléation et la croissance des cellules pendant le procédé de moussage sous le scCO2. Ensuite, les influences des conditions de moussage ainsi que celles des paramètres structuraux de la mousse de PS ont été étudiées. Les mousses de PS à cellules isotropes ont été comparées avec celles de PS à cellules orientées. Enfin, un procédé de moussage discontinu en deux étapes est développé afin de produire des mousses de PS à cellules bi-modales en utilisant le scCO2 en tant qu’agent de moussage. Cette structure unique de petites et grandes cellules réparties de manière homogène au travers de l’ensemble du volume de la mousse confère à cette dernière des propriétés particulières
In this work, scCO2 induced foaming of PP or PS is systematically studied with emphasis on the relationship between process, microstructure and mechanical properties. The first part of the thesis deals with the toughening of iPP by scCO2 induced crystallization for the fine separation of rigid crystalline domains and soft amorphous ones in the polymer matrix. The highly oriented iPP with “shish-kebab” and “spherulite” are then used for CO2 foaming to investigate the effect of crystalline structure on the formation of cell nucleation and growth. In addition, the effect of the foaming conditions and the cell structural parameters of PS foams on the mechanical properties are studied systematically. PS foams with isotropic cell morphology and oriented cell one are prepared. Finally, a two-step depressurization batch process is developed to produce bi-modal cell structure PS foams by using scCO2 as the blowing agent. This unique cell structure with both small and large cells homogenously distributed throughout the entire volume of the foam sample might have particular properties

Le travail présenté dans ce mémoire de thèse porte sur la préparation de nouveaux nanocomposites polystyrène-argile en utilisant des argiles modifiées par divers tensioactifs cationiques polymérisables fluorés. Des systèmes de référence ont aussi été envisagés en utilisant des tensioactifs classiques de structure proche de celles des surfmers (surfmers et tensioactifs hydrocarbonés) et ce, afin de mettre en évidence le rôle joué par le groupement polymérisable et l’atome de fluor sur la structure et les propriétés des nanocomposites obtenus. Les propriétés de surface des tensioactifs ont été étudiées en termes de CMC, tensions de surface et enthalpies de micellisation de Gibbs afin d’évaluer le comportement en solution de ces tensioactifs. Ces tensioactifs ont été par la suite utilisés pour modifier une montmorillonite sodée via un processus d’échange cationique. Les organoargiles ainsi obtenues ont été caractérisées par IR, ATG et DRX. Les données DRX obtenues sont en faveur d’un alignement de la majorité des surfmers fluorés en bicouche La préparation des nanocomposites polystyrène-argile contenant diverses quantités d’organoargiles variant de 1 à 15% en utilisant la technique de polymérisation radicalaire en masse ou en solution, a montré l’effet positif de l’introduction d’une chaîne fluorée et d’une fonction polymérisable sur la stabilité thermique des nanocomposites. Des morphologies exfoliées ont été obtenues pour la majorité des nanocomposites fluorés préparés. Une relation structure-propriétés de surface et propriétés thermique a été établie sur la base des analyses ATG, DRX et TEM/MEB
The work presented in this thesis focuses on the preparation of new polystyrene-clay nanocomposites using fluorinated polymerizable cationic surfactants as modifiers. Reference systems have also been proposed using conventional surfactants of similar structure than surfmers. The main objective is to highlight the role of the polymerizable group and the fluorine atoms on the structure and the properties of the obtained nanocomposites. The surface properties of surfactants were studied in terms of CMC, surface tensions and Gibbs enthalpies of micellization to evaluate the solution behavior of these surfactants. These surfactants were subsequently used to modify a sodium montmorillonite via cation exchange process. The resultant organoclays were characterized by IR, TGA and XRD analysis. XRD data are in favor of an alignment of the majority of fluorinated surfmers to form a bilayer structure while conventional surfactants tend to form a pseudotrimolecular layer. Determination of surfmer reactivity ratios by NMR was used to predict the behavior of these derivatives in radical copolymerization with styrene. Preparation of polystyrene-clay nanocomposite containing various amounts of organoclays from 1 to 15 wt% by radical polymerization process in bulk or solution, showed the positive effect of the introduction of fluorinated chain and polymerizable functional group on thermal stability of nanocomposites. Exfoliated morphologies were obtained for the majority of the fluorinated nanocomposite. A structure-surface and thermal properties relationship was established on the basis of TGA, XRD and TEM / SEM analysis

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 97-101).
This thesis describes the design, implementation, test, and evaluation of an extension to a well-known polystore called BigDAWG. As a polystore, BigDAWG binds together multiple diverse data sources into a single system that allows primarily analytical queries to be easily executed against the most appropriate engine for the job. The extension described allows the polystore to source data from APIs such as those publicly available on the internet. Further, an administrative interface was constructed to facilitate the adding, editing, and deleting of access to these APIs. These additions place power into the hands of the BigDAWG polystore user such that not only do they have the ability to source data from many new sources, but can process that data quickly and easily by using the built-in polystore casting facilities, cutting down on the time necessary to create custom ETLs to achieve the same result.
by Matthew Joseph Mucklo.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

This thesis deals with the cutting of flat shapes of polystyrene by industrial robot using Robotmaster. There are some variants of the shaped components that can create by using Robotmaster. The task of the work is also a demonstration task in the realization of use a resistance wire as a tool and polystyrene boards as a workpiece material.

Styrene was recovered from polystyrene (molecular weight of 138 000) by thermolysis in a nitrogen atmosphere at temperatures between 368$ sp circ$C and 407$ sp circ$C. The results were independent of the initial weight of polystyrene which was varied between 30 and 480 grams. Up to 70% of the polystyrene was converted to styrene. The styrene yield increased with temperature. At higher temperatures, the residue left in the reactor consisted mainly of styrene monomer, dimer and trimer (MW of 190). The maximum rate constant of volatile production was found to fit a first order model. The activation energy obtained was 166.5 kJ/mol, which is in accordance with literature values.

Plusieurs copolymeres triblocs polystyrene bloc polyisoprene bloc polystyrene, sis, ont ete soumis a l'examen des relations structures chimiques et microscopiques proprietes physiques et mecaniques. La viscosite des solutions des sis dissous dans du toluene suit une loi fonction de ne#c#c#e, nombre de nuds equivalents developpes par la chaine totale, dans le milieu. Cette loi est en ne#c#c#e#3#,#4, tant que le milieu reste concentre et enchevetre. Pour les analyses en mecanique dynamique mesurees entre 100c et +200c, nous avons montre l'importance du role joue par la longueur de chacun des blocs. On doit considerer a la fois les effets d'enchevetrements du bloc polystyrene et les nature et qualite de la morphologie. Dans le cas des elastomeres, le module tangent a la courbe de traction, etg, suit une loi derivee du modele de nielsen. Les diagrammes de mooney rivlin revelent quant a eux l'importance du role tenu par les nodules de polystyrene. Selon la longueur du segment polystyrene, celui-ci, en plus de sa fonction d'agent de reticulation chimique, peut ou non etre assimile a une charge renforcante. Le traitement des courbes d'hysterese constitue un double moyen de distinction des morphologies et de mise en evidence de phenomenes anormaux de dissipation d'energie

Le but de cette étude était de déterminer si le partage de petites molécules dans un système d'emballage/aliment change lorsque le polymère passe d’un état vitreux à caoutchoutique. La sorption par un polystyrène amorphe vitreux est un processus très lent. L’hystérésis observée entre les cycles de sorption et de désorption du n-hexane peut être due principalement à la variation de la vitesse à laquelle le système évolue au voisinage de la Tg et à une augmentation du volume libre dans le polymère. La sorption de vapeur de n-hexane ne modifie pas l’état physique du système, alors que celle du toluène induit un passage de l’état vitreux à caoutchoutique. Toutefois, le comportement du coefficient de partage du système toluène/PS reste inchangé lors de la transition vitreuse du système. L'effet de plastification provoquée par la sorption des composés volatils a été étudié. La sorption de certains composés volatils induit un abaissement significatif de la température de transition vitreuse du polystyrène. L'effet plastifiant du n-hexane lors de sa sorption par le PS était plus forte que celle des autres composés étudiés. Les valeurs de coefficients de partage du p-xylène et de l'éthylbenzène entre un film de polystyrène et l'éthylène glycol sont plus faibles que celles du n-hexane et du toluène à 25 °C. Finalement, malgré les modifications structurales induites par la sorption, l’énergie d’activation du coefficient de partage n’est pas significativement modifiée lors de la transition vitreuse
The aim of this work was to find out whether the partitioning behavior of small molecules in a polymer food packaging system changes as the system traverses through its glass transition. Sorption in glassy amorphous polystyrene is a very slow process. The large hysteresis between sorption-desorption cycles of n-hexane/PS was hypothesized to be mainly due to varying rate at which the glass transition temperature was reduced and increase in system’s volume. The equilibrium sorption in glassy amorphous polystyrene at 25 °C, of n-hexane vapor did not modify the state of the system, whereas that of toluene vapor modified the system’s state significantly. The partitioning behavior of toluene/PS remained unchanged across the glass transition of the system. The plasticization effect caused by sorption was studied and revealed that it modifies the glass transition of a volatile/PS mixtures quite significantly. Such information is useful in knowing state modifications of the system as long as sorption/migration occurs, and thus assisting interpretation. The plasticizing effect of n-hexane in amorphous PS was stronger than that of three other volatiles studied. The estimated partition coefficient values of p-xylene and ethylbenzene between polystyrene film and ethylene glycol were several times lower than the experimental values of n-hexane and toluene at 25 °C. Finally, glass transition or change from glassy to rubbery states and vice-versa does not significantly modify the activation energy of sorption

This thesis is concerned to the development of novel engineered surface materials using nitrogen-doped carbon nanotubes (CNx) that were grafted with polystyrene (PS) chains using in situ radical polymerization controlled by nitroxides. The in situ polymerization method involved two main steps, the radical attachment of a system initiator-controller that could follow a Nitroxide Mediated Radical Polymerization (NMRP) in solution. The chemically modified carbon nanotubes were used in the preparation of polymer-nanotube composites with the aim of improving the dispersion of nanotubes within the matrix, but also the interfacial adhesion between them. The produces polymer-grafted Cnxnanotubes were used as nanofillers using several kind of matrices (amorphous PS, semicrystalline polyethylene oxide (PEO) and immiscible blends PS-PEO. An extensive characterization was performed on the obtained modified CNx nantubes and polymer-nanotube composites in order to evaluate their physical and chemical properties
Cette thèse concerne le développement de nouveaux matériaux à base de nanotubes de carbone dopés à l’azote (CNx) sur lesquels des chaînes de polystyrène (PS) ont été greffés in situ par polymérisation radicalaire contrôlée par des nitroxides. La méthode de polymérisation in situ se décompose en deux étapes principales : l’attachement radicalaire d’un système initiateur – contrôleur, suivi d’une polymérisation radicalaire type NMRP (Nitroxide Mediated Polymerization) en solution. Les nanotubes de carbone modifiés chimiquement sont ensuite utilisés pour l’élaboration de composites polymères – nanotubes. Le greffage de polymère est censé améliorer la dispersion des nanotubes dans la matrice ainsi que l’adhésion interfaciale nanotubes-matrice. Plusieurs types de matrices sont étudiées (PS amorphe, PEO semi-cristallin et mélanges PS-PEO). Une caractérisation approfondie a été menée sur les composites à renfort de nanotubes greffés, pour évaluer l’impact du greffage sur les propriétés mécaniques et électriques des composites

This diploma thesis evaluates the influence of a thermal insulation of a structure on expenses related to its operation. It addresses the issues of a thermal insulation, energy loss, energy consumption, and evaluates the recovery of investments considering the insulation costs. It also monitors the insulation price projection on the total cost of the property.

Plasty, pronikající do životního prostředí ať už neúmyslně či záměrně, mohou být fragmentovány za vzniku částic v řádu mikrometrů (tzv. mikroplastů) a znečišťovat tak půdní systémy. Doposud vyvinuté analýzy pro stanovení mikroplastů v půdách jsou především zaměřeny na kvalitativní stanovení, nicméně i jejich provedení se zatím stále potýká s různými úskalími. Navíc, téměř všechny tyto analýzy vyžadují časově náročnou předúpravu vzorku. V této studii jsme se zaměřili na vývoj nové analytické metody pro kvantitativní stanovení mikroplastů polyvinylchloridu (PVC) a polystyrenu (PS) v půdách bez předchozí úpravy vzorku pomocí termogravimetrické analýzy spojené s hmotnostní spektrometrií (TGA-MS). Pro analýzu byly použity vzorky modelové půdy s nízkým obsahem organického uhlíku, které byly spikovány na výslednou koncentraci 0,23–7 hm% PVC či PS. Vzorky byly pyrolyzovány s teplotním krokem 5 K min–1 až na teplotu 1000 °C. Pyrolýzní plynné produkty byly následně analyzovány s využitím hmotnostního spektrometru. Získaná data byla normalizována pomocí externího standardu (šťavelan vápenatý). Limity detekce se pohybovaly v rozmezí 0,08–5,3 hm% pro PVC a 0,005–0,7 hm% pro PS v závislosti na zvoleném m/z. Limity kvantifikace pak byly 0,3–17,7 hm% pro PVC a 0,002–2,2 hm% pro PS. Výsledky dokazují, že spojení TGA-MS může být konkurující semikvantitativní metodou pro stanovení mikro-PVC a mikro-PS v půdě s nízkým obsahem organického uhlíku.

Polystyrene, PS, is a preferable polymer in industry, but, its brittle characteristic restricts its utilization. The aim of this study is to improve the impact strength of PS by the help of elastomeric materials SEBS-g-MA and E-BA-GMA. In order to prevent the reduction in the tensile strength of the materials, three different types of organic montmorillonites, MMT, (Cloisite®
30B, 25A and 15A) were used as fillers. Nanocomposite preparation was performed in a co-rotating twin screw extruder. Initially elastomer and organoclay contents were kept at 5wt% and 1-2wt% respectively. Well dispersed silicate layers were obtained for the nanocomposite containing SEBS-g-MA and Cloisite®
25A owing to the high viscosity of SEBS-g-MA and the solubility of polystyrene end block of SEBS with PS matrix. Owing to higher hydrophobicity of Cloisite®
15A a better dispersion was expected compared to Cloisite®
25A, but, it was concluded that two long aliphatic tails of Cloisite®
15A limited the access of polymer chains to the clay surface. The desired impact strength values could not be achieved by using 5wt% elastomeric materials
therefore, it was decided to increase the SEBS-g-MA content up to 15, 20, 30 and 40wt%. With increasing elastomer content, increasing average elastomer domain size was obtained. Also, it was observed that with the addition of organoclay, the elastomeric domain size increases since the clay particles reside in the elastomer phase and at the interphase between elastomer and PS. The mechanical test results showed that the nanocomposites containing 15 and 20wt% SEBS-g-MA have the optimum average domain size that results in better impact strength values without deteriorating tensile properties.

This thesis examines the processing behaviour of molten polystyrenes with different molecular weights and architectures, using experimental results obtained from a micro-scale processing apparatus and numerical simulations applying both empirical and molecular-based constitutive models. Processing experiments were performed using a multi-pass rheometer, a two piston capillary-type machine which principally employed a contraction then expansion slit geometry. This was able to provide flow-induced birefringence and pressure difference data at a range of flow rates from ten gram sample quantities. The parameters required to rheologically characterise the linear and non-linear viscoelastic behaviour of the polystyrenes were obtained from experiments performed using parallel plate strain-controlled rheometers. A commercial grade polydisperse polystyrene was used as a reference material and to validate the techniques used. Five monodisperse polystyrenes with molecular masses ranging from 66,000 to 485,000 kg/kmol were studied, together with two differently weighted blends of two of these. As well as these linear molecules of varying molecular weight distribution, observations were made of two polystyrenes with branched structures, one an asymmetric H, and the other a comb structure. Experimental data from the range of materials tested has shown that it is possible to distinguish differences between the types using flow birefringence in a processing flow. Monodisperse polystyrenes are notable for a high degree of symmetry between entry and exit patterns for lower molecular weights and flow rates. Blends of a small proportion of low molecular weight monodisperse with high molecular weight showed significantly improved processability, and similar birefringence to the broadly polydisperse type. Branched molecules were seen to exhibit transient stress fangs in start-up flow. A further significant experimental observation was the onset of instabilities and breakdown of continuum flow in high molecular weight monodisperse polystyrenes. The experimental data was compared with the predictions made by advanced numerical simulations, and it was found that empirical models gave generally good steady state predictions in most cases, while a molecular approach was able to predict the different transient behaviour characteristic of long chain branching, and make predictions for more extreme experimental conditions.

Polymers have ideal bulk properties for many applications. However, adhesion to many polymers is poor without surface pretreatment. This can result, for example, in peeling paint and printing, adhesive joint failure and bio-incompatibility. In applications such as painting, printing, adhesive bonding and biocompatibility, various cleaning or surface chemical modifications may be employed. A commodity polymer where pretreatment IS sometimes needed is polystyrene. This project investigated, in detail, the effects of a novel method of modification namely mediated electrochemical oxidation (MEO), as a mode of surface modification on polystyrene and a comparison was made with other polymers. The resulting modification was investigated using a range of surface analysis techniques to obtain complementary information. These included; X-ray photoelectron spectroscopy, contact angles, static secondary ion mass spectrometry, atomic force microscopy, chemical derivatisation, scanning electron microscopy, attenuated total reflection Fourier Transform infrared spectroscopy and composite lap shear joint testing. It has been shown that MEO modifies the surface of polystyrene introduced oxygen mainly as hydroxyl groups, and a small number of carbonyl groups, that are positioned only on the backbone hydrocarbon chain. This modification improved adhesion, was stable and samples could be stored in aqueous media. The resulting hydroxylation was further derivatised using an - amino acid to provide a specialised surface. This was very different from the multiple oxygen functionalities introduced in the comparison studies by UV/ozone and plasma treatments.

Dans le cadre des procédés de clarification d'eau de surface, les flocs formés au cours des étapes de coagulation et de floculation peuvent être séparés de l'eau traitée par décantation ou par flottation. Dans ce dernier cas, le procédé actuellement en vigueur est la flottation à air dissous et présente un certain nombre d'inconvénients. Ainsi, dans ce contexte, la présente thèse consiste à développer un matériau innovant, à la fois flottant et floculant, pour une application dans un procédé de flottation sans air. Dans un premier temps, l'élaboration de billes de polystyrène expansibles utilisant l'eau ou l'éthanol comme agent gonflant a été réalisée. D'autres billes ont ensuite été préparées en présence de 4-(chlorométhyl)styrène comme co-monomère puis la polymérisation par transfert d'atome amorcée en surface (SI-ATRP) de l'acrylamide a été effectuée avec succès. L'impossibilité d'expanser ces matériaux a ensuite conduit à l'exploration de nouvelles voies de synthèse avec la fonctionnalisation de matériaux flottants existants par des techniques de « grafting from » ou « grafting onto ». Quelle que soit la voie envisagée, la première étape a consisté à réduire les fonctions nitrile en amine primaire en présence d'hydrure d'aluminium lithium. Après fonctionnalisation par du bromure de bromoisobutyryle ou du chlorure d'acryloyle, il a été possible de venir greffer de l'acrylamide par SI-ATRP ou de l'amidon via un amorceur redox, respectivement. Les matériaux flottants/floculants obtenus ont été testés lors de flottatests. Les meilleurs résultats ont été obtenus avec les microsphères fonctionnalisées par de l'amidon anionique. Ces dernières ont permis d'abattre la turbidité de l'eau, ont ensuite été régénérées avec succès, par des bains d'acide oxalique ou de dithionite de sodium, et employées durant plusieurs cycles flottatest/régénération avec des résultats reproductibles
At the end of clarification process, after coagulation-flocculation steps, flocs can be removed from treated water by settling or flotation. In the latter case, Dissolved Air Flotation is the currently used process. However, this method showed important drawbacks, especially an important energetic cost due to the production of air saturated water. In that context, the goal of the reported work dealt with achieving air-free flotation using innovative floating materials. First of all, the synthesis of expandable polystyrene beads using water or ethanol as blowing agent was investigated. Other beads containing both styrene and 4-(chloromethyl)styrene were prepared. Then, surface initiated atom transfer radical polymerization of acrylamide (SI-ATRP) was achieved. Unfortunately, the expansion of such materials was not possible. Therefore, the second part focused on the functionalization of Expancel beads by “grafting from” or “grafting onto” techniques. The first step consisted in reducing some nitrile functions at the surface into primary amine ones. After functionalization with bromoisobutyryl bromide, the SI-ATRP of acrylamide was performed in water at room temperature. On the other hand, the acryloyl chloride was grafted onto amine functions, and grafting of starch was achieved using a redox initiator. All materials obtained have been used for flocculation/flotation tests and demonstrated satisfactory performances in terms of turbidity removal. Beads functionalized with starch have been successfully regenerated with oxalic acid and sodium dithionite and kept appropriate efficiency during several flotation/regeneration cycles

L‟objectif de cette thèse est de valoriser les polymères styréniques issus des déchets d‟équipements électroniques et électriques. Les polymères considérés sont le polystyrène (PS), le polystyrène choc (HIPS), le poly(acrylonitrile-butadiène-styrène) (ABS), l'ABS couplé avec du polycarbonate (ABS/PC) et le poly(styrène-acrylonitrile) (SAN). Une étude préliminaire a permis de définir deux mélanges à compatibiliser : le mélange PS/ABS et le mélange PS/PC. Pour le mélange PS/ABS, la voie de compatibilisation ionique est étudiée. L‟ajout d‟un copolymère présentant une structure ionique et la création d‟un réseau in-situ sont tentés. Ces deux voies n‟ont pas donné de résultats concluants en termes d‟amélioration des propriétés finales du mélange. Le mélange PS/PC est lui compatibilisé par ajout d‟un copolymère polystyrène bloc-poly(éthylène-butylène)-bloc-polystyrène greffé PC. Ce copolymère est tout d‟abord créé en mélangeur interne, afin d‟étudier différents catalyseurs susceptibles d‟initier le greffage, puis l‟extrusion réactive est utilisée pour synthétiser ce copolymère à grande échelle. Plusieurs taux de copolymère sont alors introduits dans le mélange PS/PC et l‟amélioration des propriétés et des microstructures prouve son effet compatibilisant
The aim of this work consists in the recycling of the styrenic polymers coming from waste of electric and electronic equipments. Polystyrene (PS), high impact polystyrene (HIPS), poly(acrylonitrile-butadiene-styrene) (ABS), its alloy with the polycarbonate (ABS/PC) and poly(styrene-acrylonitrile) (SAN) are considered. A preliminary study permits to choose two blends to study: PS/ABS and PS/PC. In the case of PS/ABS blend, the ionic way of compatibilization was studied. The addition of a copolymer containing an ionic structure and the creation of an ionic network in-situ are investigated. Both these attempts are not conclusive about the improvement of the final properties of the blend. The PS/PC blend is then compatibilized by adding a polystyrene-block-poly(ethylene-butylene)-block-polystyrene grafted polycarbonate. This copolymer is first created in an internal mixer, in order to study different catalysts able to initiate the grafting, and then the reactive extrusion is used to synthesize it on a large scale. Several amounts are introduced in the PS/PC blend and the improvement of the properties and microstructures proves its compatibilizing effect

Thesis deals with options of use waste from insulating materials. Theoretical part of thesis describes waste and insulating materials used in civil engineering. Practical part of thesis describes utilization of waste from mineral wool. Its output are options of use waste from mineral wool and selected physical properties of recycled material.

This work is focused on physical interactions of negatively charged polymers with small ionogenic fluorescent molecules. Trying to verify the presence of these interactions using fluorescence correlation spectroscopy (FCS) and provides a comprehensive view of the problem. The aim of this work is to observe the effect of concentration on the diffusion properties. P/D ratio, where P represents number of polymer binding sites and D number of dye binding sites, was chosen for this issue. Hyaluronate, sodium chondroitin sulfate and sodium polystyrene sulfonace were used as polymers and Acridine Orange, and Rhodamine 6G were chosen as fluorescent probes. The reason why this experiment uses these probes, was the assumption, that the positive charge occuring on the fluorescent probe will lead to the electrostatic interaction with the negatively charged polymer. As a result, the bond between acridine orange and polyelectrolyte was not clearly demonstrated, but the interaction with Rhodamine 6G have been proved.

Due to brittleness of polystyrene, PS, its usage area is restricted. To solve this problem and expand the usage area of PS, it can be blended and impact modified with an elastomeric material. In this study, the decrease in the modulus and tensile strength imparted by impact modification was overcome by reinforcing this mixture by incorporating organoclays and producing nanocomposites. This study consists of two parts. In the first part of this study three different types of aliphatic elastomeric materials and three different types of organoclays were used and their effects on the morphology, mechanical, thermal, and rheological properties of PS were investigated. Lotader AX8900, Lotader AX8840 and Lotader 2210 were chosen as the aliphatic elastomeric compatibilizers
and Cloisite

In this work the nonlinear behavior of concentrated polystyrene solution was examined using sliding plate rheometer developed at McGill University. In this rheometer a novel transducer is used to measure the shear stress and an optical system is used to measure birefringence during flows involving high shear rates.
The steady shear stress was found to be independent of shear rate at high shear rates. The Cox-Merz rule was found to be valid for concentrations less than 0.199 g.cm$ sp{-3}$, but a deviation from the rule was observed for higher concentrations. Sigmoidal damping functions, based on both the shear stress measurements and the birefringence measurements, were determined. The exponential stress coefficient and the third normal stress difference were calculated from experimental data for different values of exponential rate constant and different strain scale factor. The exponential rate constant was shown to have a strong influence on both the exponential stress coefficient and the third normal stress difference.

The delta-phase of the syndiotactic polystyrene/ethylbenzene system, as formed by crystallisation from dilute solution, is shown to result in a lamellar morphology, with a monoclinic crystal lattice similar to that already reported for the complex with toluene. The temperature/concentration phase diagram for sPS/ethylbenzene gels was obtained using DSC. This shows the presence of three polymer/solvent compounds, one of which contains 0.25 solvent molecules per monomer unit. For this latter compound, the stoichiometry corresponds to that proposed by Chatani et al. for the delta-phase of sPS in toluene. Combined SAXS, FTIR, DSC and TGA measurements show that an increase in the X-ray long period between 80 and 120°C is related to solvent loss and decomplexation. There is also some temporary loss in helical order. SANS measurements on the delta-phase reveal negligible isotopic fractionation. The small increase in the in-plane radius of gyration with increasing molecular weight is interpreted as evidence of a sheetlike molecular conformation, with superfolding at higher molecular weights leading to a multiple sheet structure. On transformation to the solvent-free gamma-phase, an increase in radius of gyration results from a displacement of crystal stems out of the delta-phase sheets. Further support to these conclusions is brought by intermediate and wide angle neutron scattering. Data for delta-phase are shown to be consistent with sheetlike arrangements of crystal stems along the a direction. Adjacent stems therefore show an alternation in helicity. Simulations based on a statistical model have been used to calculate statistical parameters, such as the probability of adjacency (P[A]), for which optimum agreement is found for a value of 0.8. Radii of gyration obtained from simulations are in good agreement with experimental values. The molecular weight range studied appears to cover the change from a single sheet structure to a superfolded double sheet. The same stem statistics (with P[A] = 0.8) apply, irrespective of molecular weight. Scattering data from the gamma-phase of sPS are well reproduced by a model involving some movement of stems out of the planes of sheets. SANS measurements have been made using tilted samples in order to separate in-plane and out-of-plane radii of gyration. Comparison between the out-of-plane radius and the long spacing determined from small angle X-ray measurements shows close agreement for the lower molecular weight in both delta- and gamma-phases, while R[Z] is a factor of 2 larger for the higher molecular weight. This indicates that each molecule occupies a single lamella at the lower molecular weight and, on average, two lamellae at the higher one, in both delta- and gamma-phases. The implication is that the delta- to gamma-phase transition only involves a reorganisation of chain segments within those lamellae which originally contained the molecule.

Structural and Dynamical Properties of Atactic Polystyrene in the Interface and Interphase Region Surrounding Grafted and Ungrafted Silica Nanoparticles The composite industry has long achieved enhanced material properties by mixing micro sized inorganic filler particles with a polymer matrix1,2. This is because the combination of two or more different materials can have a synergistic effect on the overall composite material properties imparting advantages that are absent in the individual constituents. A well-known example is that of adding carbon black as reinforcing material to increase tire strength, toughness, and resistance to tear and abrasion3,4. To achieve improved materials performance, the design of conventional composites has typically focused on reducing the dimensions of the filler particles. This is done in order to increase the filler surface area to enable greater interaction with the polymer matrix. Consequently, these efforts have received a significant boost with the dawn of the ‘nano era’. Wherein experimental methods and tools are now used to synthesize, characterize, and investigate matter at the nano-scale level [10-9 m] which is close to molecular and atomic dimensions. The advent of such methods is exciting as it suddenly offers new possibilities of creating novel materials that can be tailored at very small dimensions. This expectation has been derived from the notion that the behavior of materials at their nanoscale level directly influences their microscopic properties and consequently their bulk macroscopic characteristics. As is typical in any emerging field, the challenge is to understand the fundamental aspects that control the final observable properties of these composite materials. In contrast to the behavior of materials in conventional composites, recent experimental observations of polymer nanocomposites have demonstrated multifunctional changes in their properties. Examples include - but are not limited to - the decrease in the polymer viscosity5, shifts in the polymer glass transition temperature6,7, and changes in the composite material’s thermo-mechanical8,9 properties. However, what is still lacking and remains unclear are the fundamental explanations for the differences in the behavior between conventional composites and nanocomposites. In order to address questions pertaining to these differences, this PhD work was part of a large European Union consortium of universities and industrial partners, NanoModel. The aim of the group was to develop a unified scientific understanding from both experimentalists and theoreticians on the behavior of polymers in the presence of a surface. Such understanding of the important controlling parameters would ultimately support the design of industrial polymer nanocomposite materials. Therefore, both the structural and dynamical investigations always sought to address some of several important open questions that necessitated this work. These questions include among other things: (1) Does a nanoparticle influence the behavior of the surrounding polymer? (2) Since the dispersion state of the nanoparticles is known to control the resulting nanocomposite properties, which controlling parameters are important in obtaining a well-mixed polymer nanocomposite? (3) What role does the size/dimension of the nanoparticle play? (4) Is it necessary to graft or attach polymers to the filler particles, in other words, functionalizing the nanoparticles to facilitate their dispersion in the polymer melt? (5) How long should the grafted polymer chains be relative to the bulk polymer and which grafting density is optimal to achieve a good dispersion state? (6) To what extent are the polymer properties in the interface (next to the surface) and interphase (where grafted and bulk free polymer chains mix) region changed if they are at all? (7) Which parameters influence the width or extent of both the interface and interphase region? (8) Can we observe the same phenomena or changes by employing both experimental and theoretical approaches? Therefore, the contribution of this PhD thesis within the NanoModel framework was to investigate the structural and dynamical properties of atactic polystyrene in the vicinity of a silica nanoparticle as a model system for polymer nanocomposites at the atomistic level (see Figure 1.1 for a simulation snapshot). This model system was chosen because of its importance to the NanoModel partners since bulk polystyrene is an important, largely used, and well characterized polymer while silica is a typical traditional filler particle. Naturally, consortium partners like BASF would find it invaluable to produce new tailored plastics with superior properties to the traditional ones. At the same time, partners like BOSCH and CRP-FIAT would benefit from knowing the nanoparticle effect on the mechanical properties and the processing of the nanocomposite which directly impacts their injection molding processes for example. On the experimental front, Fribourg University, Juelich, and Epidoris were involved in nanocomposite sample preparation and characterization. These experimental results validated those obtained from computational studies from TU Darmstadt, National University of Athens, Trieste University, and BASF. Therefore, the influence of the nanoparticles of various diameters (3.0, 4.0, and 5.0 nm) and grafting states (0.0, 0.5, and 1.0 chains/nm2) on atactic polystyrene was studied. To perform this work, a computer molecular dynamics (MD) simulation tool, YASP10, was employed. This tool numerically solves Newton’s equations of motion for a system of interacting atoms to generate a trajectory of their movements. Following this, the resulting trajectories can be analyzed for different properties that characterize the structure, dynamics, and thermodynamics of the system. The use of atomistic MD simulations has the advantage of being able to investigate both static and dynamic properties of a system in fine detail. The ensuing results have the benefit of being related to experimental observations such as those probed by nuclear magnetic resonance11 (NMR) and dielectric spectroscopy12 (DS) studies. Additionally, other experimental techniques like neutron, x-ray, and light scattering now allow the determination of the atomistic structure of a material. Thus, computer modeling techniques interface with and complement experimental methods in understanding the link between structural and dynamical properties of polymers. While many experimental5,6,9,13-20 investigations have been performed to study the behavior of polymers at surfaces, very few atomistic21-25 computer modeling studies have been done. This necessitates the development a unified theoretical and experimental understanding of the polymer static and dynamic modifications in the presence of a surface. This is important because such changes determine in part the overall material properties. Examples of these material properties include their mechanical strength, appearance, how well they can be processed, and the duration of the polymer aging process. Additionally, this work sets a foundation for coarse-grained simulations, which investigate longer polymer chains and bigger systems. Static and dynamic properties of polymers determine whether nanoparticles form clusters or are well dispersed in a polymer melt. This is a pivotal challenge in experimental techniques because it is difficult to control the dispersion of nanoparticles, which finally determines the resulting material properties. Parameters that influence the static, dynamic, and nanoparticle dispersion state include - but are not limited to - the nanoparticle size, grafting density, the ratio of the length of grafted to free chains, and surface-polymer interactions. Therefore, developing an understanding of how these parameters interplay with each other will aid in the control and tailoring of the final nanoparticle dispersion state. The first half of this cumulative PhD thesis, chapter 2, presents results of the atactic polystyrene structure around the nanoparticle. The quantities of interest were the polymer density, radius of gyration, and its orientation relative to the nanoparticle surface. The analysis of the computer simulation output trajectory files resolved these polymer properties as a function of distance from the nanoparticle surface to quantify the surface effect. Varying both the polymer grafting density and the nanoparticle surface curvature enabled the understanding of how these two parameters interplay and influence the polymer’s structural properties. For instance, the extents of the polymer density modifications under the influence of the nanoparticle surface indicate the wettability of the surface by the polymer. This is important in mitigating adhesive failure and mechanical stress distribution in the nanocomposite material. At the same time, the density changes directly influence the polymer dynamical properties like the glass transition temperature and polymer aging processes. Therefore, understanding and being able to control these changes is vital since polymer properties like the elastic modulus and conductivity amongst many other physical properties change significantly around the polymer glass transition. These observations underscore not only the importance of the polymer in the interface region but also the width of the interphase region. The latter is influenced by the nanoparticle grafting state and the nanoparticle curvature as investigated in this work but also on the length ratio between the grafted and free polymer chains. While changes in the polymer radius of gyration give a measure of how stretched a polymer coil is, this has the effect of directly influencing the packing of polymer chains and their orientation. Additionally, the induced orientation of the polymer and its segments is important in processes that depend on transport properties such as electrical and thermal conductivity. Therefore, the different polymer structural properties are interlinked and understanding their cause-and-effect gives tuning parameters in the design of polymer nanocomposites. Complementary to structural properties discussed in chapter 2, chapter 3 forms the second half of this thesis and discusses the dynamical properties of the polymer. These included the mean-squared displacement (MSD) of the polymer chain center-of-mass and reorientational dynamics of intramolecular segment vectors. These quantities were also calculated under different nanoparticle grafting states and surface curvature. Changes in the polymer chain MSD and the reorientation of its end-to-end vector have given a measure of the global polymer mobility. To understand the local dynamics at the monomer level, the reorientation of a three-monomer and the C-Cpara segment vector as well as the backbone C-H bond vector was investigated (see Figure 1.2). The advantage of obtaining such a local resolution is that it allows for comparison with experimental NMR and DS studies which probe the C-H bond vector and the C-Cpara segment vectors, respectively. To develop a unified understanding, explanations of the dynamical property changes were linked to the previously observed structural properties either in the interface or interphase region, see chapter 2. The objectives to this thesis were to use the molecular dynamics simulation tool (YASP), setup the model system under investigation, perform the simulations, and write analysis programs to determine the different polymer properties. Therefore, I interpreted, understood, and explained my results in light of their interconnectedness as well as results from other simulations and experimental work on polymer nanocomposite systems. Finally, this work ends with chapter four which encompasses the conclusions and an outlook for further investigations.

Master's thesis consists of two parts, theoretical and practical. In the theoretical section are listed basic information about alternative aggregates used for concrete mixture, like polystyrene, cinder and recycled concrete. Further, the influence of these alternative aggregates, used as secondary raw materials, on the behaviour and properties of fresh respectively hardened concrete. Possibilities of application concrete containing secondary raw materials are mentioned. In the practical part are experimentally verified physical and mechanical properties of concrete containing crushed waste polystyrene beads, furthermore thermal insulation properties and resistance to elevated temperatures is tested. Influence of heating plant cinder powder as active addition to concrete mixture was tested. As a next is prepared concrete with replacement of coarse aggregate by cinder and recycled concrete and tested. The influence of these secondary raw materials on workability, compressive strength, frost resistance and water permeability of concrete is also defined. The last part of research is focused on recycled concrete such as main material used in mixture of aggregates bonded with cement, dispose for base layers in roads. In conclusion are discussed results from experimental research and summary of knowledge’s about using polystyrene, cinder and recycled concrete as aggregates for concrete mixtures.

Thesis (M.S.)--University of Akron, Dept. of Polymer Science, 2008.
"December, 2008." Title from electronic thesis title page (viewed 01/13/2010) Advisor, Judit E. Puskas; Faculty Reader, Gary R. Hamed; Department Chair, Ali Dhinojwala; Dean of the College, Stephen Z. D. Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

The structure and association behaviour of poly(styrene-alt-maleic anhydride) (SMA) and poly(styrene-alt-N,N-dimethylpropylamide) (SMI) polymers were studied using molecular modeling. The conformational studies were carried out at a semi-empirical PM3 level. SMA and SMI polymers were found to associate into nanotubes. These nanotubes have primary, secondary and tertiary structures. The primary structure is the conformation the polymer takes depending on the degree of protonation and its chirality. The secondary structure is the association of many polymers to form a nanotube structure. The tertiary structure is a higher order aggregation between the nanotubes.