Obtention of blends and composites of poly(hydroxyalcanoates)

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For the last few years the search for sustainable development has led to a growing interest in biodegradable polymers. Among them, Poly(hydroxyalkanoates) (PHA) are natural polyesters that are synthesized as storage materials by several microorganisms in the presence of a carbon source such as sugar or oil. They are waterproof, heat resistant, fully biodegradable and biocompatible, turning them attractive to several applications ranging from agricultural mulch films, packaging and tissue engineering among others. Unfortunately, despite the great interest that these polymers may arouse, the commercially available PHA are still expensive, relatively fragile polymers, unstable with time and present a difficult processing. Although some efforts have been spent to improve the mechanical properties of PHA obtaining blends and composites, only marginal improvements were obtained. Also, most blends and composites were obtained by solvent casting and not using conventional polymer processing methods due to the thermal degradation that these polymers suffer during melt processing. This thermal degradation is also the cause of lack of knowledge of rheological properties of PHA.