Chemically crosslinked crystalline thermoplastic polyolefin elastomer with good elasticity and improved thermo-mechanical properties. (21st July 2022)

• Record Type: Journal Article
• Authors: Zhao, Yongsheng; Ma, Yuqi; Xiong, Youhao; Qin, Tian; Zhu, Yanling; Deng, Hua; Qin, Jianbin; Shi, Xuetao; Zhang, Guangcheng
• Is Part Of: Polymer. Volume 254(2022)
• Publication Date: 2022-07-21
• Subjects: Thermoplastic elastomer (TPE) -- Chemical crosslinking -- Olefin block copolymer -- Thermo-mechanical property; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2022.125075
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Due to mechanical α-relaxation process, olefin block copolymer (OBC) has a limited heat resistance and thermo-mechanical property. In this work, peroxide-induced melt crosslinking was conducted to fabricate OBC elastomers with two types of crosslinks. It was found that orthogonal crystal structure forms in these chemically crosslinked elastomers. Interestingly, the crystallization peak temperature ( T c, p ) shifted to higher temperature after crosslinking, which is mainly due to the crystallization mode transition from confined crystallization to breakout crystallization. Based on CPMG method of LF- 1 H NMR and AFM nanomechanics, it was demonstrated that loosely crosslinked OBC achieves double crosslinks of one chemical crosslink and another well-interconnected crystalline crosslink. As a consequence, OBC elastomer with double crosslinks shows an obviously enhanced Young's modulus (∼13.5 MPa), improved high-temperature mechanical properties (∼2.2 MPa strength and ∼220% elongation at break @80 °C) and good damping property (tan δ = 0.42). Furthermore, a balanced reprocessability and elastic recovery can be reached by adjusting the quantity of chemical crosslinks. Therefore, our work can provide guidelines for structural design and related elasticity mechanisms for high performance thermoplastic polyolefin elastomer. Graphical abstract: Image 1 Highlights: The preparation of a chemically crosslinked olefin block copolymer(OBC) elastomer by peroxide-induced crosslinking. Breakout crystallization occurs in chemically crosslinked OBC elastomer. Loose chemical crosslinks can balance reprocessability and elastic recovery. Chemical crosslinking favors for enhancement of the thermo-mechanical properties.