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增长的兴趣。其中，聚(羟基烷酸酯)(PHA)是几种微生物在糖或油等碳源存在下合成的天然聚酯作为储存材料。它们防水、耐热、完全可生物降解和生物兼容，使其在农业地膜、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人们的极大兴趣，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，并且存在加工困难。虽然人们在改善PHA共混物和复合材料的力学性能方面做了一些努力，但只取得了很小的改善。此外，大多数共混物和复合材料是通过溶剂浇注获得的，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发生热降解。这种热降解也是缺乏对PHA流变性的了解的原因。 有鉴于此，本研究的目的是：1)研究聚羟基铝酸酯(PHA)的流变性能和加工性能；2)提高其在加工过程中的抗热降解性能；3)改善其力学性能，获得纳米复合材料和共混物。研究添加扩链剂、缩水甘油基改性的多面体低聚倍半硅氧烷(POSS)、可生物降解的脂肪族-芳香族共聚酯(AAC)或将增韧的PHA与粘土制成纳米复合材料的可能性，以减少在流变学测量和加工过程中发生的热降解，并提高PHA的力学性能。 这项研究将涉及5名研究生，并与蒙特利尔理工学院和法国里昂国家应用科学研究所的教授合作。

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. In view of the above the objectives of this research are to 1) study the rheological properties and processability of poly(hydroxyalcanoates) (PHA) 2) improve their resistance to thermal degradation during processing and 3) improve their mechanical properties obtaining nanocomposites and blends. The possibility of adding chain extenders, polyhedral oligomeric silsesquioxane (POSS) modified with glycidil groups, biodegradable aliphatic-aromatic copolyesters (AAC) or obtain nanocomposites of tenacified PHA with clays to reduce the thermal degradation undergone during rheological measurement and processing and improve the mechanical properties of PHA will be investigated. The research will involve 5 graduate students and collaborations with Professors of Ecole Polytechnique de Montreal and Institut National des Sciences Appliquées de Lyon, France.