Obtention of blends and composites of poly(hydroxyalcanoates)

在过去的几年里，对可持续发展的追求使人们对生物可降解聚合物的兴趣日益浓厚。其中，聚羟基烷酸酯（PHA）是在糖或油等碳源存在的情况下，由几种微生物合成的天然聚酯，作为储存材料。它们是防水、耐热、完全可生物降解和生物相容性的，使它们在农业地膜、包装和组织工程等领域的应用具有吸引力。不幸的是，尽管这些聚合物可能引起极大的兴趣，但商业上可用的PHA仍然是昂贵的，相对脆弱的聚合物，随着时间的推移不稳定，并且存在困难的加工。虽然已经花了一些努力来改善PHA的力学性能，得到共混物和复合材料，但只得到了边际的改善。此外，大多数共混物和复合材料是通过溶剂铸造获得的，而不是使用传统的聚合物加工方法，因为这些聚合物在熔融加工过程中会遭受热降解。这种热降解也是缺乏对PHA流变特性了解的原因。

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.