Study On The Preparation Of The Electric Cable Material Of Polyethylene Crosslinked By Silane And The Reaction Kinetics

The production presses and their key points of several crosslinked polyethylene materials, their some commercial products the recent advances of the crosslinking techniques, applications and marked prospect were summarized and compared. The reaction mechanism, technological process, prescription, product properties, and application of the crosslinked polyethylene by silane have been presented in the article. The graft reactions of polyethylene by silane (SGPE) and its crosslinking reaction were studied systematically and the reaction kinetics were characterized. The effects of concentration of silanes and their mechanism on reaction were investigated. The structure changes of the molecular and aggregate state in the grafting and crosslinking reaction and the relationship between the structure and properties were inspected in detail.In the process of graft the reactions of hydrolytic condensation among the silane grafted polyethylene molecular chain occurred, melt flow rate evidently decreased. The reaction of SGPE follows first order reaction kinetics. The reaction activation energy (E_a) of low density polyethylene (LDPE) grafted by vinyl trimethoxysilane (VTMOS) and vinyl triethoxysilane (VTEOS) initiated by dicumyl peroxide (DCP) are 170 and 185kJ/mol respectively. The grafting reaction velocity and its temperature and time-dependent behavior are controlled by their E_a.The crosslinking reaction of SGPE hydrolyzed water decomposition follows first order reaction kinetics on the content of initiator and water and its activation energy is 39.46kJ/mol. The cross-linkable polyethylene by silane (SCPE) can lay up a period and can prolong the storage period in the dry environment. At the same time, if not boiled by water, the SCPE exposed to the air completely during a long time also can acquire a better degree of crosslinking. The catalytic activity relationship DBTDL>DMTBL>HSt>EAA exists between the different catalyst.The major structure changes of LDPE during the grafting and crosslinking reaction are the grafting and netting of linear macromolecular, the decrease of the degree of crystallization and the thinning of crystal. The properties of crosslinked materials depend on these structure changes. Along with the increment of the gel...