Study On The Technology Of Silane Crosslinked And Halogen-free Flame Retardant Polyethylene

In the process of preparing Silane Crosslinked PE by Sioplas, silane graft is needed tocomplete cross-linking by the boiling water. On the other hand, using hydroxide.(MH) as theflame retardant to prepare flame retardant of silane cross-linked polyethylene. The product’smechanical properties decreased significantly. So, how to simplify the Sioplas process and toimprove the cross-linked polyethylene mechanical properties of flame retardant materialbecome the focus of in this study.In this paper, Silane cross-linked polyethylene was successfully prepared using stearicacid (HSt) and zinc oxide (ZnO) as water bringing agents. This process doesn’t need boilingwater to cross-link; The feasibility of the process were verified by gel content, mechanicalproperties and processability. The results indicate that when the content of HSt and ZnO(HSt:ZnO=1:1) is2.0～3.0phr, gel content of SXPE was very high in one week, and thetensile strength and breaking elongation is improved greatly. The silane cross-linked andflame retardant polyethylene was successfully prepared, using Brucite as Holgens-free FlameRetardant, ethylene vinylacetate copolymer as compatibilizer and stearic acid (HSt) and zincoxide (ZnO) as water bringing agents. The flame retardant property and mechanical propertywere investigated with oxygen index, tensile strength and breaking elongation. The resultsindicate that, the increase of cross linking degree is beneficial to flame resistance andmechanical properties of the composite; the flame resistance was significantly improved whenthe addition of Brucite content was140phr, while the mechanical property declining. Theaddition EVA was not only benefit to the flame resistance, but also to mechanical property ofcomposite.The processing property was also researched with SEM, the results indicate that thewater bringing agent has lubricating effect on the melting processing, and the moderate waterbringing agent can make the surface of extrudates smoothly. By observing the section ofsilane cross-linking PE material, it is found that the addition of EVA is benefit to thecompatibility between PE matrix and inorganic filler, making the composite more dense, thus improving the mechanical properties of the composite.