Crystallization, structure, and enhanced mechanical property of ethylene‐octene elastomer crosslinked with dicumyl peroxide

• Published in: Journal of applied polymer science 2021-07, Vol.138 (27), p.n/a
• Main Authors: Wang, Yuan‐Xia, Shi, Ying, Wang, Chen‐Chen, Cheng, Jia‐Hui, Wang, Ying, Shao, Wen‐Jun, Liu, Li‐Zhi
• Format: Article
• Language: English
• Subjects: Crosslinking; Crystal structure; Crystallinity; Crystallization; Crystals; Dicumyl peroxide; Elastomers; Materials science; Melting points; Polymers; Polyolefins; Strain; Stretching; structure‐property relationships; Synchrotron radiation; Synchrotrons; X‐ray
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.50651

Crosslinking of polyolefin elastomer (POE, ENGAGE™ 8480) with Dicumyl Peroxide (DCP) can have effects on its crystallization dynamics, crystal structure, and properties. The POE crosslinked uniformly has significantly lower crystalline ability than the one with only amorphous phase crosslinked, which, in turn, has weaker crystalline ability than neat POE. The crystallinity and melting point depend on how the POE is crosslinked. The neat POE and POE crosslinked in amorphous phase only, are investigated with DSC and in‐situ tensile/synchrotron radiation (WAXD/SAXS). In situ tensile/synchrotron X‐ray during a uniaxial stretching process indicates that severe crystal fragmentation is observed at a strain around 45%, and with further increase in strain. The stress in the crosslinked POE is significantly larger than neat POE. For both samples, crystal orientation increases sharply within the strain range up to 88% where orientation‐induced new crystals aligned in stretching direction are observed. The long period increases more in stretching direction for the crosslinked POE, consistent with larger stress in this sample, and the stress difference is more pronounced at large strains (27.3 vs. 10.9 MPa at a strain 435%). Permanent set of the crosslinked POE is smaller, consistent with less oriented crystals observed after the test for permanent set. Crosslinking of polyolefin elastomer (POE) with Dicumyl Peroxide can have effects on its crystallization dynamics, crystal structure and properties. The crystallization behavior of crosslinked POE depends on how the POE is crosslinked. Different crosslinking approaches have very different impact on the crystallization dynamics of the crosslinked POE. The long period increases more in stretching direction for the crosslinked POE with crystal region not crosslinked, consistent with larger stress in this sample.