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采用DSC对环氧丙烷聚醚三元醇/左旋聚乳酸三枝链嵌段共聚物(PPO-b-PLLA)的熔体结晶行为进行了研究.在388～407K范围内,分别采用Avrami方程和Arrhenius方程进行了结晶动力学计算.Avrami指数n值约为2.2,表明共聚物以二维生长方式进行晶体生长.基于LH结晶理论,对三枝链嵌段共聚物的结晶机理进行了探讨.实验发现该体系共聚物的RegimeⅡ和RegimeⅢ转变温度随着n(PO)∶n(LA)的增大而变化,Kg(Ⅲ)/Kg(Ⅱ)=2.0～2.2,与LH理论预期值吻合.实验结果表明三枝链的PPO链段对PLLA链段的结晶有很大影响,使其成核较均聚物困难.链折叠自由能σe和链折叠功q均高于PLLA的值.
The melt crystallization behavior of propylene oxide polyether triol / poly (L-lactide-co-PLLA) block copolymer (PPO-b-PLLA) was studied by DSC. The Avrami equation and Arrhenius Equation was used to calculate the crystallization kinetics.The Avrami index n value was about 2.2, indicating that the copolymer grows in two-dimensional growth mode.According to the LH crystallization theory, the crystallization mechanism of the three-chain block copolymer was discussed. The changes of RegimeⅡand RegimeⅢhad been observed with the increase of n (PO): n (LA), Kg (Ⅲ) / Kg (Ⅱ) = 2.0 ~ 2.2, The triadic PPO chains have a great influence on the crystallization of the PLLA chains, making it more difficult to nucleate the homopolymer. The chain folding free energy σe and chain folding work q are higher than that of PLLA.