The results show that high-molecular weight PLA can be prepared by the direct meltcondensationpolymerization at suitable technological condition and the product has good biodegradability.
结果表明：采用适当的工艺能通过熔融缩聚法制备出高分子质量的聚乳酸，且具有良好的生物降解性能。
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The double - melt behavior, thermal stability of soild state condensationpolymerization of PET and the crystallization, expansibility of PET bottle have been studied by DSC, TGA and TMA.