Crystallization and the mechanical and rheological properties of decrosslinked–crosslinked‐high‐density polyethylenes using a supercritical fluid

The crystallization, and mechanical and rheological properties of decrosslinked–crosslinked‐high‐density polyethylenes using supercritical methanol were investigated by DSC, WAXS, DMTA, and UDS. Crosslinked high‐density polyethylenes were successfully decrosslinked in a supercritical methanol condition. The residual gel content of the decrosslinked samples decreased with the reaction temperature. The crystallization behavior, mechanical, and rheological properties of the decrosslinked samples were influenced considerably by the gel content. As the gel content increased, the network gel structure restricted the chain mobility of polymer molecules in the melt state and hindered their crystallization. Thus, the nonterminal yield behavior in the melt state was enhanced and the crystallinity decreased. The dynamic elastic modulus of the decrosslinked sample in solid state increased with the increase in the crystallinity.