The Study On The Formulations And Processing Parameters Of Silane Crosslinked POE Modified Polyethylene

With the widely applications of plastic pipe, the preparation technology of silanecrosslinked polyethylene got largely improvement. However, the rigidity of the mostcrosslinked polyethylene is high which could not satisfy the applications in somespecial fields. So it is necessary to prepare crosslinked polyethylene with higherstrength and lower rigidity.In this paper, a high performance crosslinked POE modified polyethylene withlower rigidity was successfully prepared via silane-grafted water-crosslinkingtechnique. Firstly, polyethylene and POE were melting grafted with vinyl silanethrough a single screw extruder. Then, after immerse into the hot water we canprepare crosslinked POE modified polyethylene with higher strength and lowerrigidity. Meanwhile, we discussed the mechanical properties, thermal properties andmorphology of this kind of crosslinked POE modified polyethylene.Firstly, optimal preparation technology and the raw materials selection ofcrosslinked POE modified polyethylene have been obtained through studying theeffect of screw speed, the type of silane coupling agents and crosslinking time on gelcontent and mechanical properties. In the experiment, when the screw speed reach to22r/min, the gel content and the morphology of the crosslinked POE modifiedpolyethylene can reach to the best and the process of extrusion can be stability. Fromthis research we found that, Triethoxyvinylsilane (A151) is the best choice for thiscase. The study on crosslinking time indicate that, with the time increasing, thehydrolytic degree of silane increased which lead to the increasing of gel content, inturn lead to the increasing of tensile strength. Whereas, when the time exceeded12h,the tensile strength will decrease which may be caused by the thermal aging.Secondly, the effect of the content of dicumyl peroxide (DCP) and silanecoupling agent on the properties of crosslinked POE modified polyethylene are alsostudied. From the results we can seen that, with the increasing of DCP and silanecoupling agent, the gel content of crosslinked POE modified polyethylene escalating, the tensile strength increasing (the highest value is22.8MPa), elongation at breakdecreasing, and the vicat softening point increasing. However, when the DCP andsilane coupling agent exceed the optimum quantity, the properties of silanecrosslinked POE modified polyethylene will reach to a constant value. The resultsshow that, when the content of DCP reach to0.05%, the content of A151reach to3%,the properties of silane crosslinked POE modified polyethylene reach to the best.Last, we studied the aging resistance of the crosslinked POE modifiedpolyethylene. The research shows that, after heated198hours at100°C, the strengthretention was94%.