来源于可再生资源、生物降解、生物相容、易加工的左旋聚乳酸(PLLA)是最重要的生物降解高分子材料之一,但是较弱的力学性能(断裂伸长率低和韧性差)和较慢的结晶速率是影响其实际应用的两个主要因素。本项目拟在前期工作基础上，开展具有不同分子量的生物降解聚(己二酸乙二醇酯) (PEA)与PLLA共混体系的结构与性能调控的研究工作。明确PEA分子量的因素与PLLA/PEA共混体系的相容性、增塑效果之间的关系；解析共混组成、结晶条件、PEA的分子量等因素对共混体系中PLLA的结晶形态、结晶结构、结晶行为的影响规律；揭示上述因素对共混体系的力学性能、增韧机理、降解行为、降解机理的影响规律。通过本项目的开展，将更加深入地认识、理解和解决PLLA/PEA共混体系的相容性、结晶行为、性能及降解行为等研究过程中存在的关键科学问题，为制备出力学性能改善、结晶能力提高、完全生物降解的聚合物共混材料提供理论基础。

Biodegradable and biocompatible poly(L-lactide) (PLLA) is one of the most important polyesters with good processability, as the monomer for the preparation of PLLA can be obtained from renewable resources; however, the brittleness (low elongation at break) and slow crystallization rate are the main drawbacks of influencing its wider practical applications. On the basis of our previous work, we will study the structure and properties of the blends of PLLA with biodegradable poly(ethylene adipate) (PEA) with different low molecular weights. The aims of this research work are as follows. The first is to study the relationships between the different low molecular weights of PEA and the miscibility of the PLLA/PEA blends as well as the plasticizer effect of PEA. The second is to investigate the effects of the blend composition, crystallization condition, and the molecular weights of PEA on the crystalline morphology, crystal structure, and crystallization behavior of the PLLA/PEA blends. The third is to investigate the aforementioned factors on the influence of the mechanical properties, toughness mechanism, hydrolytic degradation, and degradation mechanism of the PLLA/PEA blends. Through this research, we will not only get a better understanding of the key problems of the miscibility, crystallization behaviors, properties, and hydrolytic degradation of the PLLA/PEA blends but also prepare the PLLA-based materials with fast crystallization rate, good mechanical properties, and complete biodegradability for a wider practical application.