Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-07-11T12:48:13Z No. of bitstreams: 1 ANNA RAFAELA DE MATOS COSTA - DISSERTAÇÃO (PPGCEMat) 2015.pdf: 2304206 bytes, checksum: bd88411eb6d2299d2908c8f70fbb9f1c (MD5) / Made available in DSpace on 2018-07-11T12:48:13Z (GMT). No. of bitstreams: 1 ANNA RAFAELA DE MATOS COSTA - DISSERTAÇÃO (PPGCEMat) 2015.pdf: 2304206 bytes, checksum: bd88411eb6d2299d2908c8f70fbb9f1c (MD5) Previous issue date: 2015-02-10 / CNPq / Os polímeros biodegradáveis apresentam-se como uma alternativa ambientalmente correta para a sociedade, uma vez que minimizam problemas ambientais e reduzem acúmulo de resíduos plásticos. O presente trabalho investiga a degradação e a extensão de cadeia do polímero biodegradável, poli(butileno adipato tereftalato) (PBAT) com um aditivo extensor de cadeia epoxídico (Joncryl). O PBAT sem aditivar e aditivado com diferentes concentrações de extensor de cadeia foi processado em um misturador interno de laboratório Haake Rheomix 3000 com rotores tipo “roller”. A variação da massa molar foi estimada a partir de dados de temperatura e torque versus tempo fornecidos pelo equipamento durante o processamento do fundido. O efeito do aditivo depende fortemente da temperatura de processamento. A aditivação durante o processamento do fundido nos níveis testados, não somente compensou a discreta degradação da resina durante o processamento no misturador interno como resultou no aumento líquido da massa molar: a massa molar mais que duplicou a 230°C com 2% de aditivo. Para elevadas concentrações de aditivo observaram longos tempos de indução com queda catastrófica do torque, atribuíveis à mistura imperfeita dos componentes. / Biodegradable polymers are an environmentally friendly alternative, as they minimize environmental problems and reduce accumulation of waste plastics. This work is concerned with degradation and chain extension of the biodegradable polymer poly(butylene-adipate-terephthalate) (PBAT) with an epoxidic chain extender additive (Joncryl). The PBAT without and with different concentrations chain extender was processed in a laboratory internal mixer Haake Rheomix 3000 with "roller" type rotors. The variation of molar mass was estimated from temperature and torque data versus time provided by the equipment during melt processing. The effect of the additive depends mostly on processing temperature, less on additive concentration. Incorporation of additive during melt processing not only offset the slight degradation of the resin during processing in the internal mixer, but resulted in net increase of molecular weight. The molecular weight more than doubled at 230°C with 2% additive. For high additive concentrations were observed sometimes long times of induction with catastrophic fall of torque, attributable to imperfect mixing of the components

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-07-12T12:19:19Z No. of bitstreams: 1 ALBANIZA ALVES TAVARES -DISSERTAÇAO (PPGCEMat) 2015.pdf: 2618030 bytes, checksum: e5d264d181ed1552c6946d19110c1c85 (MD5) / Made available in DSpace on 2018-07-12T12:19:19Z (GMT). No. of bitstreams: 1 ALBANIZA ALVES TAVARES -DISSERTAÇAO (PPGCEMat) 2015.pdf: 2618030 bytes, checksum: e5d264d181ed1552c6946d19110c1c85 (MD5) Previous issue date: 2015-02-11 / CNPq / Este estudo visa avaliar a influência de um oligômero multifuncional de estirenoacrílico (POLYAD PR 002), comercializado como extensor de cadeia para polímeros de condensação, no aumento da massa molar do poli (tereftalato de etileno) (PET) e, consequentemente, na restituição de suas propriedades reológicas. O comportamento foi analisado em PET pós-consumo (PETPC) oriundo de garrafas incolores do estado da Paraíba, bem como no PET virgem (PETV) para um parâmetro comparativo. Os polímeros foram processados sem e com a incorporação do aditivo extensor de cadeia em diferentes níveis, para possibilitar o desenvolvimento de diferentes grades de PET. Foi utilizado um misturador interno acoplado ao reômetro de torque Haake Rheomix 3000QC da PolyLab QC, com rotores do tipo roller operando a 265ºC e 60 rpm. Na primeira etapa, o processamento foi realizado em um tempo de 16 min, empregando diferentes concentrações do aditivo (1,5%, 3% e 5% em massa), e na segunda etapa os polímeros sem e com a incorporação do aditivo extensor, nas concentrações 1,5 e 3% em massa, foram processados e reprocessados em um tempo de 30 min. As amostras obtidas foram caracterizadas por reometria de torque. A partir de medições de torque e temperatura obtidas pelo equipamento foi possível realizar uma avaliação das massas molares. De acordo com os resultados, confirma-se que as estimativas com base em medições de torque em tempo real são indicadores rápidos e precisos da eficácia da extensão da cadeia no PET e que a incorporação do aditivo ao PETV e ao PETPC teve uma forte influência no aumento da sua massa molar. / This study is concerned with the effect of a styrene-acrylic multifunctional oligomer (POLYAD PR 002), marketed as a chain extender for condensation polymers, in the increase of molecular weight of poly (ethylene terephthalate) (PET) and, consequently, the restitution of their rheological properties. This behavior was analyzed in post-consumer PET (PETPC) from colorless bottles collected in the State of Paraíba, as well as in virgin PET (PETV) for comparison. The polymers were processed with and without the incorporation of the chain extender additive at different levels to facilitate developing different grades of PET. An internal mixer coupled to the torque rheometer Haake Rheomix 3000QC of PolyLab QC, with roller type rotors operating at 265ºC and 60 rpm was used. In the first stage, processing was performed during 16 min, with different additive concentrations (1.5%, 3% and 5% by weight) and in a second stage, polymers with and without the incorporation of additive concentrations 1.5 and 3% by weight were processed and reprocessed during 30 min. The samples were characterized by torque rheometry. From torque and temperature measurements was possible to evaluate molar masses. According to the results, it is evident that estimates based on realtime torque measurement are fast and accurate indicators of the effectiveness of chain extension, and that the incorporation of the additive to PETV and PETPC had a strong effect in increase its molar mass

No description available.

Cette thèse porte sur la relation entre le procédé de préparation et la structure des nanocomposites polypropylène/argile. Les échantillons ont été préparés au mélangeur interne dans un premier temps. Des observations au microscope électronique à balayage, complétées par des analyses en diffraction des rayons X ainsi que des mesures rhéologiques ont permis de caractériser l’état de dispersion de l’argile à différentes échelles au sein du matériau. Nous avons comparé trois argiles organophiles et montré que la compatibilité chimique entre l’argile et la matrice est un facteur primordial afin d’obtenir une bonne dispersion : la Cloisite 20 et la Dellite 67G montrent de bons états de dispersion à toutes les échelles au contraire de la Cloisite 30B. Nous avons ensuite mis en évidence l’influence de la vitesse de rotation ainsi que du temps de mélange sur l’état de dispersion de l’argile. Le seuil de percolation de l’argile dans le polypropylène a été déterminé. Le lien entre état de dispersion et cristallinité du polypropylène a également été étudié.Les échantillons ont ensuite été préparés par extrusion bivis. L’influence de la vitesse de rotation sur l’état de dispersion de l’argile a été mise en évidence, tout autant que la dégradation de la matrice aux plus fortes vitesses. L’évolution de l’état de dispersion le long de la vis a montré que si l’intercalation était rapidement atteinte sur la vis, l’exfoliation progressait linéairement avant de saturer sur les dernières zones. L’utilisation d’une température de régulation plus faible ou d’une matrice plus visqueuse n’ont pas permis d’améliorer l’état de dispersion de l’argile ni d’éviter la dégradation de la matrice. Enfin, l’utilisation du logiciel Ludovic© a permis de mieux appréhender les phénomènes thermomécaniques mis en jeu lors de l’extrusion, mais également d’optimiser le procédé. / This PhD focuses on the relationship between the preparation process and the structure of polypropylene/clay nanocomposites. First, the samples were prepared via an internal mixer. Scanning electron microscopy observations, completed by X-ray diffraction analysis and rheology measurements enabled us to characterize the clay dispersion state in the nanocomposite at different scales. Three organoclays were compared. It was shown that the chemical compatibility between the clay and the matrix was essential to ensure a good dispersion: Cloisite 20 and Dellite 67G showed good dispersion states at all scales, whereas Cloisite 30B did not. The influence of rotor speed and mixing time on the clay dispersion state was shown. The percolation threshold of the clay was determined. The link between dispersion state and crystallinity was also studied.The samples were then prepared via a twin-screw extruder. The influence of screw speed on the clay dispersion state was demonstrated, as well as the matrix degradation at high screw speed. The evolution of the dispersion state along the screw profile showed that intercalation was reached early in the screw profile, whereas exfoliation evolved linearly until the last mixing elements. A lower barrel temperature, as well as a more viscous matrix did not improve the clay dispersion state, and did not prevent the matrix degradation. Finally, the Ludovic© software allowed us to apprehend the thermomechanical phenomena involved during extrusion, but also to optimize the process.

L’objectif de cette étude est la réalisation de séparateurs de batterie haute performance par extrusion. Ces électrolytes polymères solides nécessitent d’être perméables au courant ionique mais aussi isolants électrique, tout en étant résistants mécaniquement. Une des possibilités étudiée pour le renfort mécanique est la dispersion de charges nanométriques (whiskers de cellulose) dans un polymère. Les whiskers de cellulose sont des bâtonnets cristallins d’une longueur entre 100 et 300nm et d’un diamètre entre 5 et 20 nm. Lorsque ces charges sont dispersées de façon homogène, elles forment un réseau percolant, améliorant de cette façon le renfort mécanique de la matrice pour de faibles concentrations. Le but est donc de réaliser cette dispersion dans un polymère fondu par extrusion, en comparaison avec le procédé bien établi d’évaporation de solvant. Les difficultés principales viennent de l’agglomération des whiskers de cellulose via des liaisons hydrogènes et du milieu très concentré dans lequel ces charges doivent être dispersées. Ainsi, la première partie de l’étude est de déterminer le processus de préparation des whiskers de cellulose, limitant l'agglomération et permettant d’obtenir une suspension stable. Ce système stable est nécessaire pour la formation d'un réseau par évaporation de solvant. Une fois le protocole optimisé, la deuxième partie de l’étude porte sur la dispersion de ces whiskers dans la matrice fondue au mélangeur interne et en extrusion. Les mélanges et films obtenus sont caractérisés par analyse en rhéologie dynamique, analyse thermique et analyse mécanique. Une dégradation de la matrice ainsi qu’une orientation des whiskers sont observées. Pour contourner ces contraintes, plusieurs alternatives sont utilisées. La première consiste à adsorber un copolymère sur les whiskers ; cette méthode augmente l’effet hydrodynamique mais aucun réseau n’est obtenu. La deuxième alternative est l’utilisation d’un polymère de faible masse molaire, permettant de diminuer la viscosité du mélange et par conséquent de limiter l’orientation des charges. Cette voie permet la formation d’un réseau percolant, tout en évitant la dégradation de la matrice dans l’extrudeuse. La troisième alternative utilise un copolymère de faible masse molaire synthétisé à partir d’un monomère porteur de doubles liaisons. La faible masse molaire permet de diminuer la cristallinité du séparateur et donc d’améliorer les performances ioniques à basse température. Les doubles liaisons permettent une réticulation assurant la tenue mécanique du film / The aim of this study is to produce high-performance battery separators through extrusion. These solid polymer electrolytes should be permeable to ionic current but electrically insulating, all the while maintaining sufficient mechanical resistance. To this end, the dispersion of nanometrics fillers (cellulose whiskers) in a polymer is studied. Cellulose whiskers are crystalline sticks, with a length between 100 and 300 nm and a diameter between 5 and 20 nm. It is well known that a homogeneous dispersion of these fillers allows a percolating network, improving the mechanical reinforcement of the matrix at low concentrations. The goal is to carry out this dispersion in molten polymer through extrusion, as opposed to the well-established solvent evaporation process. The main difficulties are the aggregation of cellulose whiskers which occurs through hydrogen bonding and the concentrated medium in which these fillers are dispersed. The first part of the study is to determine the optimum process to prepare cellulose whiskers in order to limit aggregation and thus obtain a stable aqueous suspension. This stable system is necessary to obtain a percolating network in the polymer matrix through solvent evaporation. Once the protocol optimised, the second part of the study focuses on the dispersion of these whiskers in the molten matrix using both the internal mixer and the extruder. Blends and films are characterized by dynamical rheology analysis, thermal analysis and mechanical analysis: a degradation of the matrix and an orientation of the whiskers are observed. To by-pass these issues, several alternatives are used. The first one involves the adsorption of a copolymer on the whiskers. This method increases the hydrodynamic effect; however no percolation network is obtained. The second alternative is to use a low molar mass polymer. This leads to a decreased polymer viscosity which limits the orientation of the fillers, allowing the percolating network to form and prevents polymer degradation. The third way uses a copolymer with a low mass molar, synthesized from a monomer which carries double bonds. The low molar mass allows the decrease of the separator crystallinity thus improving the ionic performances at low temperatures. The double bonds can crosslink under UV light, which enhances the mechanical strength of the film

No description available.

L’objectif de ce travail est une approche pluridisciplinaire dans le but de comprendre l’impact des phénomènes microscopiques, l’interaction charge-matrice avec ou sans agent de couplage et la dispersion des charges sur les propriétés macroscopiques. La caractérisation de l’impact de la stratégie de mélange avec ou sans un agent de couplage, la cinétique, l’état final et les différents scénarii de dispersion possibles sont ainsi étudiés. L’incorporation de microperles de silice dans une matrice SBR est réalisée dans un mélangeur interne. Finalement, la silice est dispersée à l’échelle nanométrique (10-100 nm). Les nanocomposites obtenus sont alors caractérisés par des techniques complémentaires (spectroscopie mécanique, MET, mesure du taux d’élastomère lié à la charge) dans le but de caractériser quantitativement les interactions charge-matrice et charge-charge. L’outil rhéologique est un outil très sensible pour caractériser l’évolution de la dispersion de charges dans une matrice élastomère. En particulier, le module de conservation G’ montre un plateau significatif pour les faibles fréquences de déformation. Ce plateau est très sensible à l’état de dispersion ainsi qu’à la nature des interactions entre les charges. En couplant les mesures rhéologiques, l'analyse d'image faite sur des photos MET et la mesure du taux d’élastomère lié, il est possible d’établir un scénario de dispersion de la silice dans l'élastomère en fonction des conditions de mélange et de mettre en évidence les paramètres élémentaires de la dispersion impliqués. En complément, la modélisation de certains modules montre toute sa pertinence dans la caractérisation de la rupture des agglomérats ou de l’évolution des interactions charge-charge au cours du mélangeage. Enfin, la dimension fractale des réseaux de charges obtenus est déterminée à partir de nos descripteurs de la dispersion / Filler dispersion in an elastomeric matrix, states and mechanisms of dispersion had to be investigated throughout the mixing process. This work focuses on a multidisciplinary approach to understand how microscopic phenomena, like rubber-filler interaction or filler dispersions, affect macroscopic properties such as rheological behavior. The incorporation of silica is realized in an internal mixer under temperature control. Finally, silica is dispersed at the nanoscale (10-100 nm). Afterwards, nanocomposites are characterized using complementary techniques in order to discuss quantitatively the nature of rubber-filler and filler-filler interactions and their effect on rheological properties. Thus, the global evolution of dispersion during the mixing is understood through these various tests. Different mechanisms in the dispersion have been observed. First, intense particle size reduction occurs at the earliest mixing times. Then, the aggregate size does not change while the amount of physically bound rubber at the surface of aggregate increases and levels off. For some silica, a second dispersion stage has been observed after the diffusion of the elastomer to the core of the aggregates. Rheology has showed to be a very sensitive tool to characterize the evolution of the dispersion in the system. Particularly, the complex shear modulus exhibits a significant plateau (Ge), at low frequency, which is very sensitive to the dispersion state and the nature of the interaction between the fillers. There is a striking correlation between the value of plateau Ge and the bound rubber content. Finally, a dispersion scenario has been established and fundamental interaction parameters have been identified