Crystalline forms of isotactic polypropylene
Crystalline forms of isotactic polypropylene
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DOI：
10.1002/macp.1964.020750113
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发表时间：
1964
影响因子：
2.5
通讯作者：
A. Turner Jones;Jean M. Aizlewood;D. R. Beckett
中科院分区：
文献类型：
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作者：
A. Turner Jones;Jean M. Aizlewood;D. R. Beckett
本文报道了等规聚丙烯两种晶型的X射线衍射图，即β晶型和γ晶型，它们与NATTA 1所描述的α晶型不同。以前只观察到单个球晶6的β-晶型现在已在结晶良好的聚合物中获得，几乎不含α-晶型。在35-70°C的温度范围内，在立体嵌段级分中获得γ-型，不含α-型。由普通的商业聚丙烯制成; γ-型在熔体冷却后形成。这两种形式的生产条件和它们的熔融行为，已通过X射线研究。由于在拉伸过程中发生了向α-型的转化，因此没有得到任何一种形式的取向纤维。两种形式都具有三元螺旋链构型。人们曾试图从未定向样品的X射线照片中推导出β-和γ-型的晶胞，并对两种形式的螺旋的堆积进行了推测。β型的准六方晶胞中至少有六条螺旋链，也可能有十二条; γ型的晶胞是三斜晶系。
The X-ray diffraction patterns of two crystalline forms of isotactic polypropylene, the β- and γ-forms distinct from the α-form described by NATTA1, have been recorded. The β-form, previously observed only as single spherulites6 has now been obtained in a well crystalline polymer, practically free of α-form. The γ-form is obtained, free of α-form, in stereoblock fractions taken over the range 35–70°C. from normal commercial polypropylenes; the γ-form is formed after cooling from the melt. The conditions for the production of the two forms and their melting behaviour, have been investigated by X-rays. Oriented fibres were not obtained in either form as conversion to α-form took place on drawing. Both forms have a ternary helical chain configuration. The derivation of the unit cells of the β- and γ-forms from X-ray photographs of unoriented specimens has been attempted and speculations have been made as to the packing of the helices in both forms. There are at least six and possibly twelve helical chains in the pseudohexagonal unit cell of the β-form; the unit cell of the γ-form is triclinic.