Probing into the Epitaxial Crystallization of beta Form Isotactic Polypropylene: From Experimental Observations to Molecular Mechanics Computation
Probing into the Epitaxial Crystallization of beta Form Isotactic Polypropylene: From Experimental Observations to Molecular Mechanics Computation
复制标题
β型等规聚丙烯外延结晶的探讨：从实验观察到分子力学计算
DOI：
10.1002/polb.24293
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Dujin Wang
中科院分区：
文献类型：
--
作者：
Zefan Wang;Wenhong Yang;Guoming Liu;Alej;ro J. Müller;Ying Zhao;Xia Dong;Kezhi Wang;Dujin Wang
与最稳定的等规聚丙烯（α-iPP）晶型相比，β-iPP具有上级的冲击强度和高温性能，但β-iPP阻挫结构的形成机理尚不清楚。首次获得了传统β-iPP成核剂N，N′-二环己基丙烯酰胺（DCHT）的单晶结构，并与β-iPP在DCHT晶体表面的外延结晶进行了关联。结合同步辐射X射线衍射和分子链堆积模型，证实了β-iPP（110）面和DCHT（001）面之间存在链轴和链间方向的二维匹配。进一步发现，外延模型有助于理解β-iPP中31螺旋堆积的阻挫结构的形成。分子力学计算表明，当DCHT的（001）面固定时，β-iPP（110）面在基底表面的堆积方式比α-iPP（010）面更稳定。本工作通过实验和计算两方面的证据阐明了β-iPP在DCHT上的外延结晶机理。© 2017威利期刊公司. J.波利姆科学，部分B：聚合物物理2017，55，418-424
Compared with the most stable crystalline form of isotactic polypropylene (α‐iPP), β‐iPP shows superior impact strength and high temperature performance, though the mechanism of how the frustrated structure of β‐iPP is formed still remains unclear. In present work, the single crystal structure of a traditional β‐iPP nucleating agent,N,N′‐dicyclohexylterephthalamide (DCHT), was obtained for the first time and correlated with the epitaxial crystallization of β‐iPP on the surface of DCHT crystal. The combination of synchrotron radiation X‐ray microdiffraction and molecular chain packing model confirmed that a two dimensional match of chain‐axis and inter‐chain direction coexists between β‐iPP (110) plane and DCHT (001) plane. It was further found that an epitaxial model is helpful to understand the formation of the frustrated structure of 31helices packing in β‐iPP. The molecular mechanics computation showed that as the (001) plane of DCHT is fixed, the packing mode of β‐iPP (110) plane on the substrate surface is more stable than that of α‐iPP (010) plane. This work clarifies the epitaxial crystallization mechanism of β‐iPP on DCHT by employing both experimental and computational evidences. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2017,55, 418–424