聚乳酸/石墨烯/离子液体复合材料的晶型结构及相转变行为

Crystal Structure and Phase Transition Behavior of PLLA/Graphene/AmimCl Nanocomposites

聚乳酸(PLLA)属于多晶型的半结晶聚合物,其各项性能与晶型结构密切相关,因此研究聚乳酸及其复合物的晶型结构及相转变,对聚乳酸的推广和应用具有重要的现实意义。采用溶液共沉淀法将离子液体液相剥离的石墨烯(Graphene/AmimCl)与PLLA共混,通过差示扫描量热仪、X射线衍射仪和变温红外研究聚乳酸/石墨烯/离子液体复合材料(PLLA/Graphene/AmimCl)的晶型结构和相转变行为。结果表明:在聚乳酸/石墨烯/离子液体复合材料中,PLLA形成α′晶型;聚乳酸/石墨烯/离子液体复合物在升温过程中经历晶型转变,在140~160℃范围内存在α′晶型向α晶型相转变行为,体现为DSC曲线熔融峰前的微弱放热峰。

Poly(L-lacticacid)(PLLA)is a semi-crystalline polymer which exhibits polymorphisms.Different crystal structures will result in different performance.For this reason,the research of crystal structure andphase transition behaviorof PLLA and its nanocomposites has very important practical significance to the promotion and application of PLLA.The crystal structure and phase transition behavior of PLLA/Graphene/AmimCl nanocomposites prepared by solution precipitation method were investigated by DSC,XRD and in-situ temperature-dependent IR spectra.The results indicated that the addition of Graphene/AmimCl resulted inα′form of PLLA.Meanwhile,the process of phase transition of PLLA/Graphene/AmimCl nanocomposites during the heating process was investigated,which indicated thatα′formhad changed intoαform when the temperature was elevated to 140—160 ℃.The phase transition ofα′-αphase resulted in the weak exothermic peak previous to the melting peak in DSC curves of PLLA/Graphene/AmimCl nanocomposites.