Obtention of blends and composites of poly(hydroxyalcanoates)

在过去的几年里，对可持续发展的探索导致了对可生物降解聚合物的日益关注。其中，聚（羟基链烷酸酯）（PHA）是在碳源如糖或油的存在下由几种微生物合成的作为储存材料的天然聚酯。它们具有防水、耐热、完全生物降解和生物相容性的特点，使它们在农业覆盖膜、包装和组织工程等多种应用中具有吸引力。不幸的是，尽管这些聚合物可能引起极大的兴趣，但可商购的PHA仍然是昂贵的、相对易碎的聚合物，随时间不稳定并且存在难以加工的问题。尽管已经花费了一些努力来改善PHA获得的共混物和复合材料的机械性能，但仅获得了边际改善。此外，大多数共混物和复合材料是通过溶剂浇铸而不是使用常规的聚合物加工方法获得的，这是由于这些聚合物在熔融加工期间遭受热降解。这种热降解也是缺乏对PHA的流变学性质的了解的原因。

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.