The utilization of biodegradable polymers is critical for developing “cradle to cradle” mindset with ecological, social and economic consequences. Poly(hydroxy butyrate-co-valerate) (PHBV) shows significant potential for many applications with a polypropylene equivalent mechanical performance. However, it has limitations including high crystallinity, brittleness, small processing window, etc. which need to be overcome before converting them into useful products. Further the development of biodegradable strain sensing polymer sensors for structural health monitoring has been a growing need. In this dissertation I utilize carbon nanotubes as a self sensing dispersed nanofiller. The impact of its addition on PHBV and a blend of PHBV with poly(butylene adipate-co-terephthalate) (PBAT) polymer was examined. Nanocomposites and blends of PHBV, PBAT, and MWCNTs were prepared by melt-blending. The effect of MWCNTs on PHBV crystallinity, crystalline phase, quasi-static and dynamic mechanical property was studied concurrently with piezoresistive response. In PHBV/PBAT blends a rare phenomenon of melting point elevation by the addition of low melting point PBAT was observed. The blends of these two semicrystalline aliphatic and aromatic polyesters were investigated by using differential scanning calorimetry, small angle X-ray scattering, dynamic mechanical analysis, surface energy measurement by contact angle method, polarized optical and scanning electron microscopy, and rheology. The study revealed a transition of immiscible blend compositions to miscible blend compositions across the 0-100 composition range. PHBV10, 20, and 30 were determined to be miscible blends based on a single Tg and rheological properties. The inter-relation between stress, strain, morphological structure and piezoresistive response of MWCNT filled PHBV and PHBV/PBAT blend system was thoroughly investigated. The outcomes of piezoreistivity study indicated MWCNT filled PHBV and PHBV/PBAT blend system as a viable technology for structural health monitoring. Finally, the compostability of pure polymer, blend system, and MWCNT filled system was studied indicating that PBAT and CNT decreased the biodegradability of PHBV with CNT being a better contributor than PBAT.

O objetivo desse trabalho foi desenvolver e caracterizar blendas poliméricas dos copolímeros de poli(hidroxibutirato-co-hidroxivalerato) (PHBV) com poli(etileno-coacetato de vinila) (EVA) contendo altos teores de acetato de vinila (VA). Os teores de VA nos EVA utilizados foram de 65% (EVA65) e 90% (EVA90) em massa. Como as propriedades finais das blendas de PHBV, copolímero derivado de fonte renovável e biocompostável, com EVA, polímero de origem petroquímica e não biocompostável, são altamente dependentes do número de fases constituintes do sistema, esse trabalho investigou inicialmente a miscibilidade desses blendas. Assim, blendas contendo entre 10 e 90% (m/m) de EVA foram preparadas a partir do estado fundido em reômetro de torque e caracterizadas por calorimetria exploratória diferencial (DSC) e microscopia eletrônica de varredura (MEV). Os resultados da reometria de torque indicaram que o EVA65 sofreu degradação termomecânica (com ramificação e/ou reticulação das cadeias), enquanto que no PHBV predominou o processo de cisão. As blendas PHBV/EVA65 apresentaram duas transições vítreas e nítida separação de fases, em todas as composições, típicas de sistemas imiscíveis. Em contraste, o EVA90 não apresentou degradação nas condições de estudo. As curvas DSC das blendas PHBV/EVA90 apresentaram uma única temperatura de transição vítrea (Tg) cuja variação em função da fração em massa de cada componente foi prevista pela equação de Fox. As micrografias indicando a presença de uma única fase comprovam que as blendas PHBV/EVA90 são totalmente miscíveis em qualquer proporção. Após essa etapa, buscou-se avaliar a influência do teor de VA nas blendas PHBV/EVA. Para atingir esse objetivo, blendas contendo 5, 10, 20 e 30% (m/m) de EVA foram preparadas em extrusora dupla rosca co-rotacional interpenetrante e a influência do teor de VA na biodegradabilidade, morfologia e comportamento térmico e mecânico dessas blendas foi investigada por ensaio de biodegradação em solo, MEV, DSC, análise termo-dinâmico mecânica (DMA) e, ensaios mecânicos de tração e impacto. Além da influência sobre as transições térmicas dos polímeros mencionada anteriormente, os resultados de DSC mostraram que a temperatura de cristalização a frio (Tcc) e a entalpia de fusão (ΔHm) do PHBV aumentaram com o aumento do teor de EVA. Porém, o teor de VA e, consequentemente a miscibilidade das blendas, teve forte influência sobre a entalpia de cristalização a frio (ΔHcc) do PHBV. A presença do EVA65 reduziu significativamente os valores de ΔHcc, enquanto para as blendas preparadas com EVA90 esses valores foram superiores ao do polímero puro, sugerindo influência direta sobre a cinética de cristalização do PHBV. De uma maneira geral, as propriedades mecânicas em tração, tais como, resistência à tração e módulo elástico diminuíram com o aumento do teor de EVA, independentemente do teor de VA nas blendas. Entretanto, a deformação na ruptura foi altamente influenciada pelo teor de VA. Blendas PHBV/EVA65 apresentaram pequeno aumento na deformação na ruptura com o aumento do teor de EVA, provavelmente devido à fraca adesão interfacial entre seus os componentes. Já a deformação na ruptura de blendas PHBV/EVA90 contendo 30% (m/m) de EVA foi de 280%, muito superior à deformação na ruptura de 1,7% do PHBV. A taxa de biodegradação das blendas PHBV/EVA foi menor que a determinada para o PHBV. Apesar da baixa perda de massa determinada no PHBV e nas blendas PHBV/EVA após 180 dias de ensaio de biodegradação, foi possível observar que blendas PHBV/EVA65 apresentaram taxas de biodegradação superiores as apresentadas pelas blendas PHBV/EVA90. Além disso, blendas PHBV/EVA65 contendo altos teores de EVA apresentaram maiores taxas de biodegradação. Nas blendas PHBV/EVA90 as maiores taxas de biodegradação foram obtidas em composições contendo baixos teores de EVA. Esses resultados demonstraram que a miscibilidade afetou a biodegradabilidade das blendas PHBV/EVA de maneira negativa. / The aim of this work was to develop and characterize blends of poly (hydroxybutyrateco-hydroxyvalerate) (PHBV) and poly (ethylene-co-vinyl acetate) (EVA) containing high amount of vinyl acetate (VA). The VA amount in the EVA used here were 65% (EVA65) and 90% (EVA90) in mass. As the final properties of PHBV blends, a polymer derived from a renewable and biocompostable source with EVA, a polymer of petrochemical and non-biocompostable origin, are highly dependent on the number of constituent phases of the system. Therefore this work initially investigated the miscibility of these blends. PHBV/EVA blends containing 10 to 90% (m/m) of EVA were prepared from the molten state in a torque rheometer and characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results of the torque rheometry indicated that EVA65 chains underwent thermomechanical degradation with branching and / or crosslinking, while in PHBV the scission process predominated. The PHBV/EVA65 blends presented two vitreous transitions and distinct phase separation, typical of immiscible systems. In contrast, EVA90 showed no degradation in the study conditions. The DSC curves of the PHBV/EVA90 blends presented a single glass transition temperature (Tg) whose variation as a function of the mass fraction of each component was predicted by the Fox equation. The micrographs indicating the presence of a single phase prove that PHBV blends/EVA90 are totally miscible in any proportion. After this step, the influence of VA amount on the PHBV/EVA blends was studied. PHBV/EVA blends containing 5, 10, 20 and 30% (m/m) EVA were prepared in an interpenetrating co-rotational double screw extruder and the influence of VA content on the biodegradability, morphology and thermal and mechanical behavior of these blends was investigated by soil biodegradation test, SEM, DSC, dynamic mechanical analysis (DMA) and mechanical tensile and impact tests. In addition to the influence on the thermal transitions aforementioned, the DSC results showed that the cold crystallization temperature (Tcc) and the melting enthalpy (ΔHm) of PHBV increased with increasing EVA amount. However, the VA content and hence the miscibility of the blends, had a remarkable influence on the cold crystallization enthalpy (ΔHcc) of PHBV. The presence of EVA65 significantly reduced ΔHcc values, while for blends prepared with EVA90 these values were higher than that of pure polymer, suggesting a direct influence on PHBV crystallization kinetics. In general, mechanical tensile properties, such as tensile strength and elastic modulus decreased with increasing EVA content, regardless of the VA content in the blends. However, the deformation at rupture was highly influenced by the VA amount. PHBV/EVA65 blends exhibited small increase in the elongation at break with increasing EVA amount, probably due to the poor interfacial adhesion between their components. The elongation at break of PHBV/EVA90 blends containing 30% (m/m) of EVA was 280%, much higher than the elongation at break of 1.7% of neat PHBV. The biodegradation rate of PHBV/EVA blends was lower than that determined for PHBV. Despite the low loss of mass determined in PHBV and PHBV/EVA blends after 180 days of biodegradation test, it was possible to observe that PHBV/EVA65 blends had higher biodegradation rates than PHBV/EVA blends90. In addition, PHBV/EVA65 blends containing high EVA amount showed higher rates of biodegradation. In the PHBV/EVA90 blends the highest rates of biodegradation were obtained in compositions containing low EVA contents. These results demonstrated that the miscibility affected the biodegradability of PHBV/EVA blends negatively.

Parmi les biopolymères, le poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) fait l’objet d’un grand intérêt de la part des chercheurs et des industriels. Cependant, sa sensibilité thermique et son comportement mécanique fragile restreint son utilisation dans certaines applications. Ainsi pour améliorer ses propriétés, deux grandes stratégies ont été suivies au cours de cette thèse. La première consiste à incorporer une argile de type halloysite (HNT), issue du gisement de Djebel Debbagh à Guelma (Algérie). À cet effet, des nanocomposites PHBV/HNT ont été élaborés par voie fondue. Les résultats de la microscopie électronique à balayage (MEB) et STEM ont montré une distribution relativement homogène de l’HNT avec la présence de larges agrégats. En conséquence et dans le but, d’améliorer la dispersion de ces nanotubes, il a été nécessaire de procéder à la modification des interfaces polymère-argile, soit par la modification chimique de l’halloysite, soit par l’incorporation d’un compatibilisant de type PHBV-g-MA dans le système binaire. Les résultats obtenus mettent en évidence la coexistence d’agrégats et de nanotubes individualisés. La seconde approche consiste à mélanger le PHBV avec un autre biopolymère comme le polybutylène succinate (PBS). Celui-ci a été choisi pour sa bonne stabilité thermique et ses bonnes propriétés mécaniques. Des systèmes hybrides ont été préparés par voie "fondue" en incorporant l’HNT et le PHBV-g-MA comme compatibilisant. L’étude révèle à travers le MEB que l’ajout de 5% en masse de PHBV-g-MA améliore la morphologie du mélange PHBV/PBS 80/20 qui se traduit par une diminution de la taille des nodules de PBS. L’ajout de 5% en masse de l’HNT dans le mélange favorise aussi la diminution de la taille des nodules de PBS. Cependant, la combinaison du PHBV-g-MA et de l’HNT limite l’effet émulsifiant de l’agent compatibilisant dû à l’agrégation de l’HNT. Les résultats de DSC et d’ATG montrent que le PHBV-g-MA n’a aucun effet sur les propriétés et la stabilité thermiques du mélange PHBV/PBS. Toutefois, la présence de l’HNT joue un rôle positif dans la diminution du pic de dégagement de chaleur (HRR). Les propriétés mécaniques du mélange ternaire PHBV/PBS/HNT avec ou sans compatibilisant sont comparables à celles du mélange pur PHBV/PBS 80/20.Une dernière partie des travaux a été menée sur le recyclage thermomécanique à travers une évaluation des effets du nombre de cycles d'excursion répétés sur le PHBV, le PBS, les nanocomposites PHBV/HNT et PBS/HNT, le mélange binaire PHBV/PBS 80/20 et ternaire PHBV/PBS 80/20+HNT avec et sans compatibilisant. Les résultats de cette étude ont montré que la recyclabilité de ces systèmes est possible du fait que la nanostructure du matériau recyclé soit améliorée et que les propriétés thermiques et mécaniques ne sont pas affectées après 5 cycles d’extrusion. / Among biopolymers, the poly (hydroxybutyrate-Co-hydroxyvalerate) (PHBV) has attracted the attention of researchers and industry. However, its thermal sensitivity and its fragility limited its use for some applications. Thus, to improve its properties, two great strategies were considering during this thesis. The first consists in incorporating halloysite (HNT), type of clay, collected from Djebel Debbagh in Guelma (Algeria). For this purpose, nanocomposites PHBV/HNT were prepared by melt compounding. The results of scanning electron microscopy (SEM) and STEM showed a relatively homogeneous distribution of the HNT with the presence of large aggregates. Consequently and in the aim to improve the dispersion of these nanotubes, it was necessary to carry out the modification of interfaces polymer-clay, either by the chemical modification of halloysite, or by the incorporation of compatibilizer like PHBV-g -MA in the binary system. The results obtained highlight the coexistence of individualized and aggregated nanotubes.The second approach consists in mixing the PHBV with another biopolymère like polybutylene succinate (PBS). This one was selected for its good thermal stability and its good mechanical properties. Hybrid systems were prepared by melt compounding by incorporating HNT and PHBV-g-MA as compatibilizers. The SEM analysis reveals that the addition of 5wt.% of PHBV-g-MA improves morphology of PHBV/PBS 80/20 blend inducing a reduction in the size of PBS nodules. The addition of 5wt.% of the HNT in the blend favorites also the reduction in the size of PBS nodules. However, the combination of PHBV-g-MA and the HNT limits the emulsifying effect of the compatibilizer due to the aggregation of the HNT. DSC analysis and TGA show that PHBV-g-MA has no effect on the thermal properties and the thermal stability PHBV/PBS blend. However, the presence of the HNT plays a positive role in the reduction in the peak of heat release rate (HRR). The mechanical properties of ternary mixture PHBV/PBS/HNT with or without compatibilisant are comparable with those of PHBV/PBS 80/20 pure blend.Another study came supplemented this work from thesis while being focused on the thermomechanical recycling of the PHBV, the PBS, nanocomposites PHBV/HNT and PBS/HNT, the PHBV/PBS 80/20 binary blend and PHBV/PBS 80/20+ HNT ternary blend with and without compatibilization. The results of this study showed that the recyclability of these systems is possible owing to the fact that the nanostructure of recycled material is improved and that the thermal and mechanical properties are not affected after 5 cycles of extrusion.

O objetivo desse trabalho foi desenvolver e caracterizar blendas poliméricas dos copolímeros de poli(hidroxibutirato-co-hidroxivalerato) (PHBV) com poli(etileno-coacetato de vinila) (EVA) contendo altos teores de acetato de vinila (VA). Os teores de VA nos EVA utilizados foram de 65% (EVA65) e 90% (EVA90) em massa. Como as propriedades finais das blendas de PHBV, copolímero derivado de fonte renovável e biocompostável, com EVA, polímero de origem petroquímica e não biocompostável, são altamente dependentes do número de fases constituintes do sistema, esse trabalho investigou inicialmente a miscibilidade desses blendas. Assim, blendas contendo entre 10 e 90% (m/m) de EVA foram preparadas a partir do estado fundido em reômetro de torque e caracterizadas por calorimetria exploratória diferencial (DSC) e microscopia eletrônica de varredura (MEV). Os resultados da reometria de torque indicaram que o EVA65 sofreu degradação termomecânica (com ramificação e/ou reticulação das cadeias), enquanto que no PHBV predominou o processo de cisão. As blendas PHBV/EVA65 apresentaram duas transições vítreas e nítida separação de fases, em todas as composições, típicas de sistemas imiscíveis. Em contraste, o EVA90 não apresentou degradação nas condições de estudo. As curvas DSC das blendas PHBV/EVA90 apresentaram uma única temperatura de transição vítrea (Tg) cuja variação em função da fração em massa de cada componente foi prevista pela equação de Fox. As micrografias indicando a presença de uma única fase comprovam que as blendas PHBV/EVA90 são totalmente miscíveis em qualquer proporção. Após essa etapa, buscou-se avaliar a influência do teor de VA nas blendas PHBV/EVA. Para atingir esse objetivo, blendas contendo 5, 10, 20 e 30% (m/m) de EVA foram preparadas em extrusora dupla rosca co-rotacional interpenetrante e a influência do teor de VA na biodegradabilidade, morfologia e comportamento térmico e mecânico dessas blendas foi investigada por ensaio de biodegradação em solo, MEV, DSC, análise termo-dinâmico mecânica (DMA) e, ensaios mecânicos de tração e impacto. Além da influência sobre as transições térmicas dos polímeros mencionada anteriormente, os resultados de DSC mostraram que a temperatura de cristalização a frio (Tcc) e a entalpia de fusão (ΔHm) do PHBV aumentaram com o aumento do teor de EVA. Porém, o teor de VA e, consequentemente a miscibilidade das blendas, teve forte influência sobre a entalpia de cristalização a frio (ΔHcc) do PHBV. A presença do EVA65 reduziu significativamente os valores de ΔHcc, enquanto para as blendas preparadas com EVA90 esses valores foram superiores ao do polímero puro, sugerindo influência direta sobre a cinética de cristalização do PHBV. De uma maneira geral, as propriedades mecânicas em tração, tais como, resistência à tração e módulo elástico diminuíram com o aumento do teor de EVA, independentemente do teor de VA nas blendas. Entretanto, a deformação na ruptura foi altamente influenciada pelo teor de VA. Blendas PHBV/EVA65 apresentaram pequeno aumento na deformação na ruptura com o aumento do teor de EVA, provavelmente devido à fraca adesão interfacial entre seus os componentes. Já a deformação na ruptura de blendas PHBV/EVA90 contendo 30% (m/m) de EVA foi de 280%, muito superior à deformação na ruptura de 1,7% do PHBV. A taxa de biodegradação das blendas PHBV/EVA foi menor que a determinada para o PHBV. Apesar da baixa perda de massa determinada no PHBV e nas blendas PHBV/EVA após 180 dias de ensaio de biodegradação, foi possível observar que blendas PHBV/EVA65 apresentaram taxas de biodegradação superiores as apresentadas pelas blendas PHBV/EVA90. Além disso, blendas PHBV/EVA65 contendo altos teores de EVA apresentaram maiores taxas de biodegradação. Nas blendas PHBV/EVA90 as maiores taxas de biodegradação foram obtidas em composições contendo baixos teores de EVA. Esses resultados demonstraram que a miscibilidade afetou a biodegradabilidade das blendas PHBV/EVA de maneira negativa. / The aim of this work was to develop and characterize blends of poly (hydroxybutyrateco-hydroxyvalerate) (PHBV) and poly (ethylene-co-vinyl acetate) (EVA) containing high amount of vinyl acetate (VA). The VA amount in the EVA used here were 65% (EVA65) and 90% (EVA90) in mass. As the final properties of PHBV blends, a polymer derived from a renewable and biocompostable source with EVA, a polymer of petrochemical and non-biocompostable origin, are highly dependent on the number of constituent phases of the system. Therefore this work initially investigated the miscibility of these blends. PHBV/EVA blends containing 10 to 90% (m/m) of EVA were prepared from the molten state in a torque rheometer and characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results of the torque rheometry indicated that EVA65 chains underwent thermomechanical degradation with branching and / or crosslinking, while in PHBV the scission process predominated. The PHBV/EVA65 blends presented two vitreous transitions and distinct phase separation, typical of immiscible systems. In contrast, EVA90 showed no degradation in the study conditions. The DSC curves of the PHBV/EVA90 blends presented a single glass transition temperature (Tg) whose variation as a function of the mass fraction of each component was predicted by the Fox equation. The micrographs indicating the presence of a single phase prove that PHBV blends/EVA90 are totally miscible in any proportion. After this step, the influence of VA amount on the PHBV/EVA blends was studied. PHBV/EVA blends containing 5, 10, 20 and 30% (m/m) EVA were prepared in an interpenetrating co-rotational double screw extruder and the influence of VA content on the biodegradability, morphology and thermal and mechanical behavior of these blends was investigated by soil biodegradation test, SEM, DSC, dynamic mechanical analysis (DMA) and mechanical tensile and impact tests. In addition to the influence on the thermal transitions aforementioned, the DSC results showed that the cold crystallization temperature (Tcc) and the melting enthalpy (ΔHm) of PHBV increased with increasing EVA amount. However, the VA content and hence the miscibility of the blends, had a remarkable influence on the cold crystallization enthalpy (ΔHcc) of PHBV. The presence of EVA65 significantly reduced ΔHcc values, while for blends prepared with EVA90 these values were higher than that of pure polymer, suggesting a direct influence on PHBV crystallization kinetics. In general, mechanical tensile properties, such as tensile strength and elastic modulus decreased with increasing EVA content, regardless of the VA content in the blends. However, the deformation at rupture was highly influenced by the VA amount. PHBV/EVA65 blends exhibited small increase in the elongation at break with increasing EVA amount, probably due to the poor interfacial adhesion between their components. The elongation at break of PHBV/EVA90 blends containing 30% (m/m) of EVA was 280%, much higher than the elongation at break of 1.7% of neat PHBV. The biodegradation rate of PHBV/EVA blends was lower than that determined for PHBV. Despite the low loss of mass determined in PHBV and PHBV/EVA blends after 180 days of biodegradation test, it was possible to observe that PHBV/EVA65 blends had higher biodegradation rates than PHBV/EVA blends90. In addition, PHBV/EVA65 blends containing high EVA amount showed higher rates of biodegradation. In the PHBV/EVA90 blends the highest rates of biodegradation were obtained in compositions containing low EVA contents. These results demonstrated that the miscibility affected the biodegradability of PHBV/EVA blends negatively.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV is a biodegradable polyester produced by various microorganisms, which has been studied as an option for the production of disposable items in place of polymers derived from petroleum, thus contributing to the preservation of the environment. However, this thermoplastic has some disadvantages that limit its use in industrial scale applications: the relative difficulty of processing, low elongation at break, high degree of crystallinity and high cost of production relative to conventional polymers. An alternative to improve the properties of PHBV is the incorporation of small amounts of clay to the polymer, producing polymer /clay composites. The attapulgite is a typical fibrous clay. It has a surface area around 125 to 210 m2 /g and a cation exchange capacity from 20 to 30 milliequivalents per 100g of clay. The objective of this work was the production and characterization of biodegradable composites of poly (3-hydroxybutyrate-co- 3-hydroxyvalerate) - PHBV reinforced with natural attapulgite (AT) or attapulgite modified with hexadecylmethylammonium chloride (ATM) in different compositions ( 1, 3 and 5%). The composites were characterized by X-Ray Diffraction (XRD), Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Nuclear Magnetic Resonance (NMR). The best results were obtained with incorporation of ATM levels greater than 3% (w /w). In these cases, it was observed reduction of the degree of crystallinity and decreasing of melting and glass transition temperatures as compared to PHBV films. However, the presence of attapulgite decreased the thermal stability of PHBV. / O poli(3-hidroxibutirato-co-3-hidroxivalerato) - PHBV é um poliéster biodegradável, produzido por diversos microorganismos que vem sendo estudado como uma opção para a produção de artigos descartáveis em substituição a polímeros derivados de petróleo, contribuindo, assim, para a preservação do meio ambiente. No entanto, este termoplástico apresenta algumas desvantagens que limitam seu uso no desenvolvimento de aplicações industriais: relativa dificuldade de processamento, baixo alongamento na ruptura, alto grau de cristalinidade e custo elevado de produção em relação a polímeros convencionais. Uma alternativa para melhorar as propriedades do PHBV é a incorporação de pequenas quantidades de argilomineral ao polímero, produzindo compósitos polímero/argila. A atapulgita é um argilomineral tipicamente fibroso. Possui uma área superficial em torno de 125 a 210 m2/g e uma capacidade de troca catiônica de 20 a 30 miliequivalentes por 100g de argila. O objetivo deste trabalho foi a obtenção e caracterização de nanocompósitos biodegradáveis de poli (3- hidroxibutirato-co-3-hidroxivalerato) - PHBV reforçados com atapulgita natural (AT) ou com atapulgita modificada com cloreto de hexadecil trimetil amônio (ATM), em diferentes composições (1, 3 e 5%). Os compósitos foram caracterizados por Difração de Raios X (DRX), Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), Microscopia Eletrônica de Varredura (MEV), Calorimetria Diferencial de Varredura (DSC), Análise Termogravimétrica (TGA) e Ressonância Magnética Nuclear (RMN). Quando comparados com os filmes de PHBV, a incorporação de teores de ATM maiores do que 3% (p/p) propiciaram a redução do grau de cristalinidade, diminuição das temperaturas de fusão e de transição vítrea. A presença da atapulgita diminuiu a estabilidade térmica do PHBV. Foi observada uma diminuição na temperatura de cristalização e uma diminuição no grau de cristalinidade do polímero em função do acréscimo de argila à matriz do PHBV.

Ce travail a pour objectif de développer des biocomposites à base de poly(3-hydroxybutyrate-co-3-hydroxyvalérate) (PHBV) et de farine grignons d'olive (FGO) préparés par mélange fondu. Il s'articule autour de quatre parties. La première partie comprend une étude de la morphologie et des propriétés physiques des échantillons biocomposites PHBV/FGO aux taux de charge de 10, 20 et 30% en masse. Les résultats indiquent que le système PHBV/FGO se caractérise par une séparation de phase dont le nombre et la taille des particules de FGO augmentent avec le taux de charge. De plus, la stabilité thermique et les propriétés barrières vis à vis de la vapeur d'eau et de l'oxygène ont diminué. Par contre, l'incorporation de la FGO dans le PHBV induit une augmentation du module d'Young qui s'accentue avec le taux de charge. La même tendance est également observée avec le module de conservation déterminé par DMA. Dans la seconde partie, l'impact du PHBV-g-MA comme agent compatibilisant dans les biocomposites PHBV/FGO a été évalué en fonction du taux de charge. La caractérisation morphologique du système ternaire a révélé que la présence du PHBV-g-MA dans les biocomposites PHBV/FGO induit une meilleure adhésion interfaciale entre les particules de la FGO et la matrice PHBV en raison des interactions charge-matrice. En conséquence, une nette amélioration des propriétés mécaniques, viscoélastiques et barrières aux gaz (vapeur d'eau et oxygène) est observée. Dans la troisième partie, une modification chimique de la FGO avec le trimethoxy (octadecyl)-silane (TMOS) et son influence sur la morphologie et les propriétés physiques de biocomposites PHBV/FGO: 80/20 ont été étudiées. Les résultats révèlent une dispersion fine et homogène de la FGO traitée au TMOS dans la matrice PHBV avec en apparence moins de microvides en comparaison avec le biocomposite non modifié. Les propriétés physico-mécaniques du biocomposite PHBV/FGO modifiée sont sensiblement améliorées. La dernière partie consacrée à une étude du vieillissement hygrothermique dans l'eau de mer à 25 et 40°C de films de biocomposites PHBV/FGO: 80/20 avant et après modification, révèle que la FGO favorise la cinétique de dégradation du système PHBV/FGO indépendamment du traitement. Toutefois, le biocomposite PHBV/FGO traité avec des organo-silanes se caractérise relativement par une résistance à la dégradation hygrothermique à 25 et 40°C par rapport au reste des échantillons biocomposites. / This work aims to develop a biocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyvalérate) (PHBV) and olive husk flour (OHF) prepared by melt compounding. It's articulated around four parts. The first part includes a study of the morphology and physical properties of the PHBV/OHF biocomposite samples at the loading rates of 10, 20 and 30 wt%. The results indicate that the PHBV/OHF system is characterized by a phase separation whose number and size of OHF particles increases with the loading rate. Moreover, the thermal stability and the barrier properties against water vapor and oxygen have decreased. On the other hand, the incorporation of the OHF in the PHBV matrix induces an increase in the Young's modulus which is accentuated with filler content. The same trend is also observed with the storage modulus determined by DMA. In the second part, the effects of PHBV-g-MA used as the compatibilizer for PHBV/OHF biocomposites were evaluated as a function of the loading rate. The morphological characterization of the ternary system revealed that the presence of PHBV-g-MA in the PHBV/OHF biocomposites induces better interfacial adhesion between the OHF particles and the PHBV matrix due to filler-matrix interactions. Consequently, a significant improvement in the mechanical, viscoelastic and gas barrier properties (water vapor and oxygen) is observed. In the third part, a chemical modification of OHF with trimethoxy(octadecyl)-silane (TMOS) and its influence on the morphology and physical properties of PHBV/OHF: 80/20 biocomposites was studied. The results reveal a fine and homogeneous dispersion of the TMOS-treated OHF in the PHBV matrix with apparently fewer microvides compared to the unmodified biocomposite. The physical and mechanical properties of the modified PHBV/OHF biocomposite are significantly improved. The last part devoted to a study of the hygrothermal aging in sea water at 25 and 40°C of films of biocomposites PHBV/OHF: 80/20 before and after modification reveals that the OHF promotes the degradation kinetics of the PHBV/OHF system regardless of treatment. However, the organo-silane-treated PHBV/OHF biocomposite is relatively characterized by a resistance to hygrothermal degradation at 25 and 40°C compared to the rest of the biocomposite samples.

Various commodity plastics used today are based on fossil fuels. Most of these plastics are non-biodegradable and will persist in the environment over a long time. The bioplastics from renewable resources have the potential to support a greener economy. The two of such renewably resourced bioplastics are poly (hydroxyl butyrate-co-valerate), PHBV and poly (butylene succinate), PBS. We have used petro-based PBS in our study, but renewable resource based PBS is expected to be available on a commercial scale in a very near future. These two bioplastics are both biodegradable. These two bioplastics are both biodegradable. In our study we have used PBS from petroleum resource but PHBV is a brittle bioplastic with a high modulus value and a low elongation at break while PBS is a low modulus bioplastic with a high elongation at break. Complementary properties can be obtained by blending PHBV and PBS. The direct melt blends showed poor mechanical properties due to limited interaction between PHBV and PBS phases. This research focuses on increasing the interaction between PHBV and PBS blends by using compatibilizers. The compatibilizers used in this thesis were dicumyl peroxide, DCP and trimethylolpropane triacrylate, TMPTA. Use of an in situ compatibilization method was done for the melt mixing of PHBV and PBS yielding blends with improved characteristics. The investigations were performed at three different ratios of PHBV and PBS blends. The increase in the compatibility between the two phases was demonstrated through various thermal, thermo-mechanical, rheological and morphological means. The increase in elongation at break was used as a primary marker for compatibilization. The optimization of DCP and TMPTA was carried out, which showed the enhanced interaction between PHBV and PBS phases, with the successful stress transfer from PHBV phase to the PBS phase resulting in increase in elongation at break. Inward shifts in tan delta peak on addition of DCP and TMPTA to the blends also showed increase in compatibility between the two phases. The interfacial adhesion between a brittle and ductile polymer, PHBV and PBS respectively was increased by using DCP and TMPTA. This opened gateways to various novel applications of PHBV and PBS blends via in situ reactive extrusion process. / The Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA) for their financial support via New directions research program (SR9235). We would also like to thank Canadian Foundation for Innovation (CFI) and Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA) for their equipment supports.

Submitted by Regina Correa (rehecorrea@gmail.com) on 2016-09-12T13:33:11Z No. of bitstreams: 1 DissBU.pdf: 6586964 bytes, checksum: 934910138375a2c3d090ed0f1d148376 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T14:59:22Z (GMT) No. of bitstreams: 1 DissBU.pdf: 6586964 bytes, checksum: 934910138375a2c3d090ed0f1d148376 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T14:59:29Z (GMT) No. of bitstreams: 1 DissBU.pdf: 6586964 bytes, checksum: 934910138375a2c3d090ed0f1d148376 (MD5) / Made available in DSpace on 2016-09-13T14:59:37Z (GMT). No. of bitstreams: 1 DissBU.pdf: 6586964 bytes, checksum: 934910138375a2c3d090ed0f1d148376 (MD5) Previous issue date: 2014-11-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / This research project aimed to develop high value-added products such as biodegradable composites reinforced with cellulose nanofibrils (CNF) making use of Amazonian pioneer plant species, useful in restoration of degraded forest areas. The initial objective was to obtain CNF from two pioneer species (Ochroma pyramidale and Spathelia excelsa) using a friction milling process. The oxidation effect of the bleached fibers mediated by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) on the efficiency of the mechanical defibrillation process was studied. CNF were successfully obtained and the oxidation process favored a higher degree of defibrillation. The morphology analysis allowed the observation of CNF with smaller diameter and more dispersed. The final crystalinity index of the oxidized CNF was decreased, according to X-ray diffraction results, but its thermal stability was not altered, as observed by thermogravimetry (TG). Another objective of this study was to develop nanocomposites of a biodegradable poly(hydroxybutyrate-cohydroxyvalerate) (PHBV) matrix reinforced with eucalyptus CNF through melt processing. CNF were mixed in aqueous solution in the presence of poly(ethylene oxide) (PEO), and then were freeze-dried and milled for feeding in a twin-screw extruder, followed by injection molding. The influence of CNF and PEO on the crystallinity index and crystallization rate of PHBV, as well as the mechanical, thermal, dynamic-mechanical, rheological and morphological properties of the nanocomposites were evaluated. A small increase in mechanical properties in the presence of CNF was observed, limited by the agglomeration of CNF during the drying process, even in the presence of PEO. From the thermal analysis, it can be concluded that the CNF acted as a nucleating agent for PHBV, accelerating its crystallization. The thermal stability of the PHBV did not change in the presence of CNF and PEO, as revealed by TG. / Este trabalho buscou colaborar com a proposta de desenvolvimento de produtos de alto valor agregado, como compósitos biodegradáveis reforçados com nanofibrilas de celulose (NFC), que façam uso de espécies vegetais pioneiras amazônicas úteis na recuperação de áreas florestais degradadas. O objetivo inicial foi a obtenção de NFC de duas espécies pioneiras (Ochroma pyramidale e Spathelia excelsa) utilizando moinho de fricção. O efeito da oxidação das fibras branqueadas, mediada por catalisador 2,2,6,6- tetrametilpiperidino-1-oxilo (TEMPO), na eficiência deste processo de desfibrilação mecânica foi estudado. As NFC foram obtidas com sucesso e o processo de oxidação permitiu a obtenção de maior grau de desfibrilação. A análise de morfologia por Microscopia Eletrônica de Transmissão permitiu a observação de fibrilas de menor diâmetro e mais dispersas. O índice de cristalinidade final das mesmas foi diminuído, conforme resultados de Difração de Raio-X, mas sua estabilidade térmica não foi alterada, conforme termogravimetria. Outro objetivo deste trabalho foi desenvolver nanobiocompósitos poliméricos no estado fundido de uma matriz biodegradável poli(hidroxibutirato-co-hidroxivalerato) (PHBV) reforçada com NFC de eucalipto disponíveis comercialmente. As NFC foram misturadas em solução aquosa na presença de poli(óxido de etileno) (PEO), e foram então liofilizadas e moídas para alimentação em extrusora de dupla rosca, seguido de moldagem por injeção. Foram avaliadas a influência da presença de NFC e PEO no índice de cristalinidade e cinética de cristalização do PHBV, e nas propriedades mecânicas de tração e impacto, térmicas, dinâmico mecânicas, reológicas e morfológicas dos nanobiocompósitos. Foi observado um incremento sutil nas propriedades mecânicas na presença das NFC, limitado pela aglomeração das mesmas durante o processo de secagem, mesmo na presença do PEO. A partir da análise térmica conclui-se que as NFC atuaram como agente nucleante na matriz de PHBV, acelerando sua cristalização. A estabilidade térmica do PHBV não foi alterada na presença de NFC e PEO, conforme termogravimetria realizada.

Poly(3-hydroxybuttersäure-co-3-hydroxyvaleriansäure), PHBV, ist ein Copolyester, der auf biologischem Weg durch Bakterien herstellbar und ein steifes sowie relativ festes Polymer ist. Seine Biokompatibilität und biologische Abbaubarkeit weckt das Interesse für diverse Anwendungen in Pharmazie und Medizin. PHBV reagiert mit Abbau empfindlich auf zugleich thermische und mechanische Belastungen, was ein Problem für die Verarbeitung darstellt. Produkte aus PHBV aus einmal geschmolzenem und verarbeitetem Pulver sind hochkristallin. Daher ist das Material spröde. Ferner wirkt sich die hohe Kristallinität sowie eine große Änderung der Dichte beim Abkühlen der Schmelze nachteilig auf die Spinnbarkeit des Materials aus. Nach dem Passieren der Spinndüse ziehen sich die Spinnfäden zusammen, was die Gefahr eines Fadenrisses beim Spinnen erhöht. Aufgrund der relativ hohen Kristallinität des Materials und einer verzögerten Kristallisationskinetik bei gesponnenen Polymerfäden kommt es zur Nachkristallisation in einem erheblichen Ausmaß, die Fäden verkleben nach dem Aufwickeln auf den Galetten und reißen beim Abwickeln. Zur Behebung der Nachteile wurden Verarbeitungsbedingungen vor allem bei Schmelzspinnprozessen mit der Kolbenspinnanlage und bei Mischungsprozessen optimiert. Die Polymermischungen und ?verbundstoffe enthalten kugelförmige Mikropartikel verschiedener Morphologie, die zuvor synthetisiert und charakterisiert wurden. Vor allem mit Vinylgruppen modifizierte Silikat-Submikropartikel mindern die Sprödigkeit von PHBV.

Poly(3-hydroxybuttersäure-co-3-hydroxyvaleriansäure), PHBV, ist ein Copolyester, der auf biologischem Weg durch Bakterien herstellbar und ein steifes sowie relativ festes Polymer ist. Seine Biokompatibilität und biologische Abbaubarkeit weckt das Interesse für diverse Anwendungen in Pharmazie und Medizin. PHBV reagiert mit Abbau empfindlich auf zugleich thermische und mechanische Belastungen, was ein Problem für die Verarbeitung darstellt. Produkte aus PHBV aus einmal geschmolzenem und verarbeitetem Pulver sind hochkristallin. Daher ist das Material spröde. Ferner wirkt sich die hohe Kristallinität sowie eine große Änderung der Dichte beim Abkühlen der Schmelze nachteilig auf die Spinnbarkeit des Materials aus. Nach dem Passieren der Spinndüse ziehen sich die Spinnfäden zusammen, was die Gefahr eines Fadenrisses beim Spinnen erhöht. Aufgrund der relativ hohen Kristallinität des Materials und einer verzögerten Kristallisationskinetik bei gesponnenen Polymerfäden kommt es zur Nachkristallisation in einem erheblichen Ausmaß, die Fäden verkleben nach dem Aufwickeln auf den Galetten und reißen beim Abwickeln. Zur Behebung der Nachteile wurden Verarbeitungsbedingungen vor allem bei Schmelzspinnprozessen mit der Kolbenspinnanlage und bei Mischungsprozessen optimiert. Die Polymermischungen und ?verbundstoffe enthalten kugelförmige Mikropartikel verschiedener Morphologie, die zuvor synthetisiert und charakterisiert wurden. Vor allem mit Vinylgruppen modifizierte Silikat-Submikropartikel mindern die Sprödigkeit von PHBV.