文献类型：期刊文献

英文题名：Molecular dynamics study of the isothermal crystallization mechanism of polyethylene chain: the combined effects of chain length and temperature

作者：Gao, Rui[1];He, Xuelian[1];Zhang, Haiyang[1];Shao, Yunqi[1];Liu, Zhen[1];Liu, Boping[1]

机构：[1]E China Univ Sci & Technol, State Key Lab Chem Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China

年份：2016

卷号：22

期号：3

外文期刊名：JOURNAL OF MOLECULAR MODELING

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000371428800016)】；

基金：This work is supported financially by the National Natural Science Foundation of China (No. 51573048), the research program of the State Key Laboratory of Chemical Engineering, the Fundamental Research Funds for the Central Universities and the Program of Introducing Talents of Discipline to Universities (B08021) and China Scholarship Council (No. 201406740018). The authors would like to thank Prof. Wenbing Hu from Nanjing University and Prof. Huai Sun from Shanghai Jiao Tong University for useful discussions and kind suggestions; and thank Prof. Tiziana di Luccio and Joey Kim for their great help and valuable suggestions in English writing.

语种：英文

外文关键词：Chain length; Isothermal crystallization; Molecular dynamics simulation; Polyethylene

摘要：A molecular level understanding of the polyethylene (PE) crystallization process was elucidated by molecular dynamics simulation of three states, with varying chain length and temperature. The process can be classified into the following three states: (1) nucleation controlled state, (2) competitive state of crystal growth process and new nuclei formation, and (3) crystal growth controlled state, which could be quantified by the evolution of nuclei number. With increasing chain length, two phenomena occur: the single crystallization mechanism changes from state (1) to (3), and the crystal size increases while the b/a axial ratio in the lateral surface decreases. These changes can be explained from a thermodynamic point of view, in that the van der Waals (vdW) interaction per CH2 unit is strengthened and more nucleation sites are generated for longer chain. Size effect (meaning different surface fractions when the chain collapses into a globule) was an important factor determining vdW energy per unit and the crystallization states of a single PE chain. On the other hand, the crystallization states were independent of chain length for short chains systems with the same size effect. In both conditions, a long chain generates multi-crystal domains, and a short chain prefers a single crystal domain. Our results not only provide molecular level evidence for crystallization states but also clarify the influence of chain length on the crystallization process.