The Influence of Ethyl Branch on Formation of Shish-Kebab Crystals in Bimodal Polyethylene under Shear at Low Temperature  

作　　者：Zong-Bao Wang Yi-Min Mao Xu-Ke Li Yi-Guo Li Chatchai Jarumaneeroj Boonyakeat Thitisak Piyawan Tiyapiboonchaiya Wonchalerm Rungswangd Benjamin S.Hsiao 

机构地区：[1]Ningbo Key Laboratory of Specialty Polymers,School of Materials Science and Chemical Engineering,Ningbo University,Ningbo 315211,China [2]Department of Materials Science and Engineering,University of Maryland,College Park,Maryland 20742,USA [3]NIST Center for Neutron Research,National Institute of Standards and Technology,Gaithersburg,Maryland 20899,USA [4]SCG Chemicals Co.,Ltd.,Siam Cement Group(SCG).1 Siam Cement Rd.,Bangsue,Bangkok 10800,Thailand [5]USA Department of Chemistry,Stony Brook University,Stony Brook,NY 11794-3400,USA

出　　处：《Chinese Journal of Polymer Science》2021年第8期1050-1058,I0008,共10页高分子科学（英文版）

基　　金：the National Natural Science Foundation of China(Nos.51773101 and 51973097).

摘　　要：Formation of shish-kebab crystals using a bimodal polyethylene system containing high molecular weight(HMW)component with different ethyl branch contents was investigated.In situ small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)techniques were used to monitor the formation and evolution of shish-kebab structure sheared at low temperature in simple shear mode and low rate.Only the bimodal PE with no branch formed shish-kebab crystals at the shear temperature of 129℃,and the shish length increased with the crystallization time,while bimodal PE with branch has no observable shish under the same conditions.The degree of crystallization for bimodal PE with no branch increased with time up to above 7%,while those with ethyl branch increased continually up to above 23%.Furthermore,bimodal PE's Hermans orientation factor with no branch increased to 0.60,while those with ethyl branch only increased to a value below 0.15.This study indicated that the shish-kebab crystal formed at the low temperature of 129℃is due to the stretch of entangled chains under shear for the bimodal PE with no branch.Only partly oriented lamellar crystals were formed for the bimodal PE with ethyl branch.All the results at the shear temperatures higher,closed to,and lower than the melting point,the modulation of shish crystals formation owing to different mechanisms of the coil-stretch transition and the stretched network by changing shear temperature was achieved in the bimodal PE samples.

关 键 词：Bimodal polyethylene SHISH-KEBAB Ethyl branch SHEAR 

分 类 号：TQ325.12[化学工程—合成树脂塑料工业]