Molecular Mobility in the Amorphous Phase Determines the Critical Strain of Fibrillation in the Tensile Stretching of Polyethylene

作     者：Rui Li Guo-Xing Yang Ya-Nan Qin Li Liu Zhi-Yong Jiang Rui Li;Guo-Xing Yang;Ya-Nan Qin;Li Liu;Zhi-Yong Jiang

作者机构：School of Chemistry and Chemical EngineeringState Key Laboratory of Urban Water Resource and EnvironmentHarbin Institute of TechnologyHarbin 150001China Daqing Petrochemical Research CenterPetrochemical Research InstituteChina National Petroleum CorporationDaqing 163714China State Key Laboratory of Polymer Physics and ChemistryChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China 

出 版 物：《Chinese Journal of Polymer Science》 (高分子科学（英文版）)

年 卷 期：2020年第38卷第7期

页      面：740-747,I0006页

核心收录：

学科分类：08[工学] 0817[工学-化学工程与技术] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 

基　　金：This work was financially supported by the National Natural gieile Fuundaliun uf Chine(No.11074119) Jilin ScienuiL and Technological Development Program(No.20180519001JH).We thank Prof.Yongfeng Men and Dr,Victor Litvinov for helpful discussions. 

主　　题：SAXS Bimodal high density polyethylene Molecular mobility 

摘      要：The microstructural development of bimodal high density polyethylene subjected to tensile deformation was investigated as a function of strain after annealing at different temperatures by means of a scanning synchrotron small angle X-ray scattering(SAXS)technique.Two different deformation mechanisms were activated in sequence upon tensile deformation:intralamellar slipping of crystalline blocks dominates the deformation behavior at small deformations whereas a stress-induced crystalline block fragmentation and recrystallization process occurs at a critical strain yielding new crystallites with the molecular chains preferentially oriented along the drawing direction.The critical strain associated with the lamellar-to-fibrillar transition was found to be ca.0.9 in bimodal sample,which is significantly larger than that observed for unimodal high-density polyethylene(0.4).This observation is primarily due to the fact that the bimodal sample possesses a greater mobility of the amorphous phase and thereby a reduced modulus of the entangled amorphous network.The conclusion of the mobility of the amorphous phase as a determining factor for the critical strain was further proven by the 1H-NMR T2 relaxation time.All these findings contribute to our understanding of the excellent slow crack growth resistance of bimodal polyethylene for pipe application.