In order to explore the influence of polyethylene microstructure on the crosslinking behavior and network structure of insulation materials

the peroxide chemical crosslinking behavior of four polyethylene insulation materials was systematically analyzed by gel permeation chromatography combined with online detector

infrared spectroscopy

and vulcanization tests. In addition

the number of weight average branching points

along with the content and length of long chain branches in the resin

was theoretically calculated. The results indicate that the consumption of terminal vinyl groups during crosslinking is more than twice that of ethylene groups

which can provide additional chemical crosslinking points and improve crosslinking efficiency. High molecular weight long chain segments contribute to the construction of crosslinked networks

but excessively high average molecular weight between crosslinking points weakens the density of the network structure

limiting the synergistic improvement of thermomechanical properties. The effect of long chain branches on the crosslinked network structure is bidirectional

on the one hand

longer branches and their higher content can increase the number of cross-linking reaction sites

thereby enhancing the degree of crosslinking; On the other hand

the limitation of polymer coil size and the self entanglement effect of long branches can weaken the structural stability of cross-linked networks. Therefore

in the synthesis process of crosslinked polyethylene

appropriate regulation of chain structure and bond structure parameters can effectively reduce the content of crosslinking agents

and achieve synergistic optimization of the scorch resistance and thermal mechanical properties

which can provide theoretical guidance for the development of insulation materials for high voltage cables.