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考察了固相(后)聚合工艺(SSP)对L-聚乳酸(PLLA)的粘均相对分子质量(Mη)、力学性能、热性能的影响。结果表明:PLLAMη的变化幅度随原料PLLA的平均相对分子质量、SSP的温度变化而变化,在适宜的工艺条件下,PLLA的Mη提高幅度最高能达到SSP前的2.9倍,PLLA的拉伸强度、断裂伸长率、弯曲强度、弯曲模量等冲击强度都有所改善;它们的初始分解温度提高了90℃左右,热稳定性能显著改善。在SSP过程中,得到了PLLA的白色结晶状的副产物,初步鉴定此副产物为丙交酯及其低聚物。
The effects of solid phase (post) polymerization process (SSP) on the viscosity-average molecular weight (Mη), mechanical properties and thermal properties of L-PLA were investigated. The results show that the change range of PLLAMη varies with the average relative molecular mass of PLLA and the temperature of SSP. Under the proper process conditions, the maximum increment of PLLA can reach 2.9 times that of SSP. The tensile strength, Impact strength such as elongation at break, flexural strength and flexural modulus are all improved; their initial decomposition temperature is increased by about 90 ° C, and thermal stability is significantly improved. During the SSP process, white crystalline by-products of PLLA were obtained. The by-products were identified as lactide and its oligomers.