等规聚丙烯β晶型向α晶型的相转变行为研究进展  

Research Progress on Phase Transformation Behavior of β to α-Form Isotactic Polypropylene

作　　者：甄薇薇[1] 李慧慧[1] 闫寿科[1] 

机构地区：[1]北京化工大学化工资源有效利用国家重点实验室,北京100029

出　　处：《高分子学报》2017年第4期580-586,共7页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21174014,21374007)资助项目

摘　　要：等规聚丙烯(iPP)是典型的多晶型半结晶性聚合物,其常见晶型有单斜(α),三方(β),三斜(γ)以及四方或双四方(e),其中稳定性最好的α晶型和处于亚稳态的β晶型工业和经济价值较大,因此二者之间的相转变行为得到了人们的广泛关注.本文综述了近年来β→α-iPP生长相转变的研究进展.在高临界温度(141°C)和低临界温度(100°C)区间内,β-iPP生长速率高于α-iPP,而温度高于141°C,或低于100°C,由于α-iPP在动力学上占优势,β-iPP会发生向α-iPP的生长转变.但由于α-iPP是热力学上最稳定的晶型,β-iPP熔融重结晶过程也会发生β→α-iPP相转变.此外,拉伸形变过程中也会发生β→α-iPP相转变,广泛用于制备聚丙烯气体交换膜、过滤膜或锂电池隔膜等.目前对变形过程中的β→α-iPP相转变机理还存在争议,本文也对2种主要的机理进行了介绍,并对聚丙烯晶型转变行为的研究方向进行了展望.Isotactic polypropylene （iPP） is a semi-crystalline polymer which exhibits polymorphisms, designated respectively as monoclinic α-, trigonal β-, orthorhombic γ- and tetragonal ε-form. Due to the industrial and economic value, α- and β-iPP have been widely studied, and the transformation behavior between these two phases has been extensively investigated. Therefore, studies in recent years with the focus on such topic are generally reviewed in this article. Originally, the growth rate of β-iPP is over that of α-iPP between high critical temperature （141 ℃） and low critical temperature （100 - 105 ℃）. But when the temperature is higher than 141℃ or lower than 100 ℃, β →α-iPP phase transformation could occur, for α-iPP is kinetically favorable. This growth transformation can be realized by two-step crystallization of/PP. Besides, such phase transformation would take place during melting and recrystallization because α-iPP crystals are thermodynamically more stable. Moreover, the β→ α-iPP phase transformation can also be observed during deformation at room temperature or high temperature, and microporous membranes can be prepared via this process due to the higher density of α-iPP. Such products could be used as gas exchange membrane, filter membrane or separator of lithium-ion batteries. Since the transformation mechanism during deformation is still controversial, the article also reviews two proposed ideas about it. One is that the transformation during stretching should experience partial melting and recrystallization, and the other is just a solid-solid phase transformation. In addition, there are problems remaining that should be further explored about the β → α-iPP phase transformation. For example, it is still unknown whether there is crystallographic relationship between new formed α-iPP and original α-iPP during two-step crystallization, or it is just realized by a nucleation process. So, this will be an appealing direction for researchers in the field of polymer p

关 键 词：等规聚丙烯 α相等规聚丙烯 β相等规聚丙烯 相转变 

分 类 号：TQ325.14[化学工程—合成树脂塑料工业]