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Polymorph selection during melt crystallization of the isotactic polybutene-1 homopolymer depending on the melt state and crystallization pressure.
Soft Matter ( IF 2.9 ) Pub Date : 2020-08-18 , DOI: 10.1039/d0sm01231a
Beibei Dong 1 , Xiaokang Yang 1 , Youxin Ji 1 , Fengmei Su 1 , Chunguang Shao 1 , Chuntai Liu 1
Affiliation  

This work investigated the crystalline forms obtained from melt crystallization in the isotactic polybutene-1 (iPB-1) homopolymer via manipulation of the temperature at which samples were melted (Tmelt) and crystallization pressure (Pcry). Unlike the results under atmospheric conditions where the molten sample crystallized into the pure form II and the crystallization temperature and kinetics were affected obviously by Tmelt, the melted sample crystallized into forms II or I′ under high pressure, depending on Tmelt and Pcry. The content of form I′ decreases with increasing Tmelt or decreasing Pcry. Meanwhile, the critical pressure for the formation of pure form I′ increases with increasing Tmelt. The formation of form I′ is attributed to the memory effect of the melt which preserved some ordered sequence of crystal and the high pressure (Pcry) which suppressed the nucleation and growth of the kinetically favored form II, which results in the formation of form I'. In addition, the melt crystallized form II transforms to form I under high pressure conditions; thus forms I, I′ and II are observed. The relative contents of the three crystalline forms on samples for different Tmelt and Pcry are obtained in this work. The result shows that the crystalline forms in melt crystallization of iPB-1 can be customized by regulating the melt state and crystallization conditions.

中文翻译:


全同立构聚丁烯-1 均聚物熔融结晶过程中多晶型的选择取决于熔融状态和结晶压力。



这项工作研究了通过控制样品熔化温度( Tmelt )和结晶压力Pcry )从全同立构聚丁烯-1(iPB-1)均聚物中熔融结晶获得的晶型。与大气条件下熔融样品结晶为纯晶型 II 且结晶温度和动力学受T熔体影响明显不同,熔融样品在高压下结晶为晶型 II 或 I',具体取决于T熔体P晶型。晶型I'的含量随着Tmel增加或Pcry减少而减少。同时,形成纯晶型I'的临界压力随着熔体温度的增加而增加。 I'型的形成归因于熔体的记忆效应,它保留了晶体的一些有序序列,以及高压Pcry )抑制了动力学上有利的II型的成核和生长,从而导致了I'型的形成我'。另外,熔融晶型II在高压条件下转变为晶型I;因此观察到形式I、I'和II。 本工作获得了不同熔点温度熔点温度下样品上三种晶型的相对含量。结果表明,iPB-1熔融结晶时的晶型可以通过调节熔融状态和结晶条件来定制。
更新日期:2020-10-15
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