Polymorphism in isotactic polypropylene
Polymorphism in isotactic polypropylene
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DOI：
10.1080/00222346908217088
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发表时间：
1969-03
期刊：
影响因子：
--
通讯作者：
Darrell R. Morrow
中科院分区：
文献类型：
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作者：
Darrell R. Morrow
本文研究了等规聚丙烯三种不同多晶型晶相的形成条件。讨论了晶化条件与特定晶相形成的关系。引用的证据支持的假设，β型的全同立构聚丙烯可以生产时，适当的成核材料存在。结果表明，在特定的高压结晶条件下，可以生成三斜γ相，它不会因热或机械应力的作用而转变为单斜α相。基于对稳定性、密度和结构的考虑，建议聚合物的平衡晶型是γ-晶型而不是通常观察到的α-晶型。
Abstract The conditions under which a given form of any of the three distinct polymorphic crystalline phases of isotactic polypropylene can be obtained have been investigated. The relationship between crystallization conditions and the formation of a given crystalline phase is discussed. Evidence is cited in support of the hypothesis that the β-form of isotactic polypropylene can be produced only when appropriate nucleating materials are present. It is shown that under particular high-pressure crystallization conditions a triclinic γ-phase can be produced that does, not convert to the monoclinic α-phase either by action of heat or mechanical stress. Based on considerations of stability, density, and structure, it is suggested that the equilibrium crystal form of the polymer is the γ-form rather than the α-form which is ordinarily observed.