聚乙二醇——聚对苯二甲酸乙二酯嵌段共聚物的多重熔融和结构重建

MULTIPLE MELTING AND CRYSTALLINE STRUCTURE IN PEG—PET BLOCK COPOLYMER

本文应用差示扫描量热法(DSC)、广角 X 光衍射(WAXD)、偏光显微镜(PLM)、小角激光光散射(SALS)等方法,对聚乙二醇—聚对苯二甲酸乙二酯(PEG—PET)嵌段共聚物的结晶和熔融行为进行了研究。结果显示,在 DSC 扫描过程中,PEG—PET 经历了多重熔融与结构再组合的过程.当PET 链段结晶时,PEG 链段被挤出 PET 折叠链的表面,并不生成共晶.在 PET 的折叠链的弯折处,由于 PEG 链段的内增塑作用.使折叠链内应力降低.堆砌紧密,得到了 PET 在同等条件下所不能得到的完整的晶面衍射.嵌段共聚物在200℃淬火2h,PEG 链段无法挤出球晶的表面,从而形成了混品.且球晶的光轴方向发生偏转.

The crystallization and melting behaviors of PEG—PET block copolymer are studied by means ofDSC,WAXD,PLM and SALS,etc.Results show the sample undergoes a process of multiple meltingduring DSC scanning.When PET chains crystallize,PEG chains are squeezed out of the surface offolded PET chains and no co-crystallization appears.Because of internal plasticization of PEG chains,the internal stress at PET folds decreases,helping to form a kind of close piled crystal.The perfect X-ray diffraction of PEG-PET crystal plane can be determined,but that of PET cannot be got under thesame annealing condition.After being annealed at 200℃ for 2 hours,the PET spherulite grows somuch that PEG chains cannot be squeezed out of its surface.Thus a blended crystal forms,its opticalaxis direction deflected.