中文摘要：

研究了热处理时间对P（3HB—co-4HB）摩尔质量的影响，并考察了热处理时间和摩尔质量对加工后的产物在溶剂中的溶解性、结晶性能，结晶结构、力学性能和熔体流动性的影响。研究结果表明：随着热处理时间的增加，P（3HB-co-4HB）共聚酯的摩尔质量降低，在溶剂中的溶解性变好，熔点和结晶温度有所升高，共聚酯的结晶结构没有发生改变，拉伸强度和断裂伸长率降低，熔体质量流动速率升高。当热处理时间为4min时，共聚酯的数均摩尔质量为2．3×10^5g／mol时，共聚酯具有较好的加工流动性，并保持了较好的力学性能。

英文摘要：

The effect of heat processing time on the molecular weight of poly （3-hydroxylbutyrate-co-4-hydroxylbutyrate） （P（3HB-co-4HB））, as well as the effects of the heat processing time and molecular weight on the solubility, crystalline property, crystalline structure, mechanical property and melting index of processed product, was studied. The results showed with the increase of heating time, the molecular weight decreased, and the solubility of the samples become better, melting temperature and crystalline temperature rose, both the tensile strength and elongation at break decreased, MFR increased, however, the crystalline structure did not change. When the processing time was 4 min and molecular weight was 2.3 × 10^5 g/mol, the obtained product had a good processibility and better mechanical properties.