Neste trabalho, foi estudada a miscibilidade de misturas de um PHB constituído de frações de alta e baixa massa molar com um PLA de alta massa molar. Os materiais extrudados foram analisados pelas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia dielétrica (DE) e análises dinâmico-mecânicas (DMA). A partir dos resultados observou-se o distinto comportamento cristalino das frações de PHB, assim como a miscibilidade parcial do PLA com o PHB de baixa massa molar.

In this work, the miscibility of a PHB formed by high and low molar mass fractions and a low molar mass PLA was studied. The extruded materials were analyzed by differential scanning calorimetry (DSC), dielectric spectroscopy (DS) and dynamic mechanical analysis (DMA). From these results, it was observed an unique behavior from the PHB fractions, and the partial miscibility of PLA onto low molar mass PHB.

O poli(hidroxibutirato) - PHB - e o poli(ácido lático) - PLA - são dois poliésteres termoplásticos com grande potencial para uso em aplicações industriais, sendo viáveis nos principais métodos de processamento e totalmente biodegradáveis. Porém, devido às suas propriedades mecânicas limitadas, necessitam de modificações para melhorar seu desempenho e tornarem-se industrialmente competitivos. Foram estudadas propriedades e características destes dois polímeros e suas misturas poliméricas, avaliando a possibilidade do uso na preparação de filmes finos por extrusão para embalagens. Verificou-se a possibilidade de produção de filmes finos de misturas PHB/PLA, através das técnicas de extrusão de filmes, planos e tubulares soprados. Porém, para viabilizar a produção industrial destes filmes, modificações devem ser realizadas no processo de produção e/ou no preparo da mistura polimérica através da aditivação, com o objetivo de reduzir a alta adesividade dos filmes durante o seu processamento.

Poly(hydroxybutyrate) - PHB - and poly(latic acid) - PLA - are thermoplastic polyesters with huge potential for industrial applications since they are fully biodegradable and can be processed by usual methods. However, due to their limited mechanical properties, they need to be modified to achieve better performance and become industrially competitive. The properties of both polymers and their mixtures were evaluated in order to investigate their application for thin films extrusion, for packages. PHB/PLA thin films were produced by extrusion and blow film techniques. To allow for an industrial production process, the preparation of the polymer blend should be changed in order to decrease their high adhesion during processing.

The ever increasing accumulation of plastic waste in the environment has motivated research on polymers that degrade rapidly after being discarded as possible substitutes for conventional inert plastics. Biodegradable polymers can be an alternative, since they have non-toxic residual products and low environmental permanence. Poly (hydroxybutyrate) is a biodegradable polymer with a strong potential for industrial purposes, but its thermal instability and fragility limit its applications. Thus, an alternative to improve the processability and properties of poly (hydroxybutyrate) is to mix it with another polymer, not necessarily a biodegradable one. In this work, different mixtures of poly(hydroxybutyrate) or PHB and polypropylene or PP were extruded and injected. After processing, the blends were studied and their miscibility, mechanical properties and degradability in different soils were analyzed. The main results indicated that the PHB/PP blends had better mechanical properties than pure PHB, as well as improved immiscibility and higher degradation in alkaline soil. The poly-hydroxybutyrate/polypropylene blends showed a tendency for lower crystallinity and stiffness of the polymer matrix, proportional to the amount of polypropylene in the blends, rendering them less stiff and fragile. The degradation tests showed that both pure PHB and blends with 90% PHB and 10% PP were degraded, with loss of their mechanical properties and weight.