等规聚丙烯拉伸取向片晶结构的温度关联性  

Temperature-dependent Lamellae Structure in Stretch-oriented Isotactic Polypropylene

作　　者：林浩[1] 严飞[1] 国江[1] 黄想 姜胜宝[1] 许梦伊 LIN Hao;YAN Fei;GUO Jiang;HUANG Xiang;JIANG Sheng-bao;XU Meng-yi(China Electric Power Research Institute,Wuhan 430074,China)

机构地区：[1]中国电力科学研究院,武汉430074

出　　处：《高分子通报》2024年第3期358-367,共10页Polymer Bulletin

基　　金：国家电工技术中心科技项目“改性聚丙烯及新型介电材料成膜技术研究”(项目号GY83-22-004)资助。

摘　　要：为了探究加工温度对热拉伸聚丙烯取向晶体结构的影响规律,将等规聚丙烯(iPP)铸片在不同温度下拉伸到相同应变,并通过二维广角/小角X射线散射、差示扫描量热仪、动态力学分析等手段,对拉伸取向iPP的微观结构特性进行了系统研究。结果表明:经过热拉伸后,由球晶形貌演变成纤维晶形貌,纤维晶体由高度取向片晶和无定形层交替堆叠排列构成;升高温度引起结晶性能增强,结晶度和片晶平均厚度随温度连续递增;提高温度造成结晶相与无定形相之间的物性差异变大,两相链段运动松弛温度的变化趋势相反;热拉伸过程中新形成了不同厚度(熔点)的片晶,高熔点片晶是通过熔融-再结晶机理形成,而低熔点片晶由应变诱导结晶方式获得。本研究初步阐明了拉伸温度对聚丙烯取向片晶结构的影响规律和作用机制,对于开展结晶聚合物拉伸加工过程中多层次结构调控与性能优化具有参考价值。In this work,the working roles of stretching temperature(Ts)on impacting the microstructure characteristics of oriented isotactic polypropylene(iPP)were surveyed in depth by a combination of two-dimentional wide-angle/small-angle X-ray scattering,differential scanning calorimetry,dynamic mechanical analysis,etc.The results show that the initial spherulitic morphology transformed into the fibrillar crystal morphology after experiencing hot-stretching process,and that the crystalline fibrils consist of the altermative stacks of highly orentied lamellae and amorphous layers.A Ts-dominant crystallization enhancement was found as that:crystallinity and mean lamellar thickness increased monotonously as elevating Ts.Meanwhile,as the Ts increases,the physical properties of the crystalline phase begin to diverge significantly from those of the amorphous phase,resulting in opposite trends for chain relaxation in the two phases.Two fractions of lamellae with different thicknesses(melt point)are newly formed during the hot stretching process.The lamellae with higher melt point are arisen from the melt-recrystallization mechansim,while the occurrence of low-melt point lamellae obeys the strain-induced crystallization mechanism.This work provides a new understanding into the rule of structural manipulation of semicrystalline polymers during stretch processing.

关 键 词：等规聚丙烯 拉伸温度 片晶 结晶度 熔点 

分 类 号：TQ325.14[化学工程—合成树脂塑料工业]