Study of the Photocrosslinking of Ethylene Propylene Diene Monomer Terpolymer Under UV Irradiation

Abstract

The photocrosslinking of thick samples of 5‐ethylidene‐2‐norbornene–ethylene propylene diene monomer (ENB‐EPDM) under air at room temperature was investigated. First, a model study was carried out on low‐molecular weight oligomers: squalene, 1,2‐polybutadiene, and 1,4‐polybutadiene. Several crosslinking agents (meth(acrylics), bismaleimide, and thiol) combined with various photoinitiators were tested to improve the reactivity of these oligomers under UV irradiation. Gel contents, crosslinking densities, viscosities, and viscoelastic properties were measured in order to characterize the extent of crosslinking. Acrylate‐based crosslinking agents appeared to be the most reactive species and these results were then applied to a low‐molecular weight EPDM. Several photoinitiators were tested and benzophenone turned out to be the most efficient photoinitiator when combined with trimethylolpropane triacrylate. Finally, a commercial EPDM was subsequently photocrosslinked and high gel content and crosslinking density were obtained after only 2 min of irradiation. POLYM. ENG. SCI., 60:95–103, 2020. © 2019 Society of Plastics Engineers

Modification of poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) via free‐radical grafting and its photo‐crosslinking

“…None have been reported to lead to a crosslinking of this copolymer in the presence of a stimulus like UV light, contrary to SBS or ethylene-propylene-diene monomer (EPDM) which are well-known to react via UV light when activated by peroxides with or without mercaptans. [18][19][20] The grafting of SEBS with cycloaliphatic epoxide has never been reported previously to our knowledge. In this study, a two-step approach was considered: first a freeradical grafting of a vinylic monomer onto SEBS polymer chains with peroxide and then the crosslinking of the functionalized SEBS in the presence of UV light as illustrated in Figure 1.…”