不饱和硅烷熔融挤出接枝聚乙烯的研究

采用熔融挤出法对低密度聚乙烯进行硅烷接枝，然后在催化剂二月桂酸二丁基锡存在进行水解交联，对接枝产物的熔体流动速率和交联样品的凝胶率的影响因素进行了系统的研究，接枝单体为乙烯基三乙氧基硅烷，主要引发剂为过氧化二异丙苯。

MELT GRAFTING OF UNSATURATED SILNANES ONTO POLYETHYLENES VIA EXTRUSION

Vinyltriethoxysilane(VTES) was grafted onto low density polyethylene(PE) using a Haake twin screw extruder. The grafted products were crosslinked in hot water in the presence of dibutyltin dilaurate. The influences of VTES concentration, initiator type and concentration, PE type, additive type and concentration, as well as processing conditions on the melt flow rate( MFR ) of grafted PE and the gel fraction of crosslinked product were investigated. Gel fraction increases with VTES concentration and reaches a constant value at about 2 mass% VTES, while MFR goes through an optimum value with increasing VTES concentration. Gel fraction increases with increasing initiator concentration at first, and then leveled out at higher initiator concentrations, but MFR decreases further at higher initiator concentrations. High gel fraction and MFR were obtained at the same time with powdered PE. Processing conditions also affect the grafting reaction, there exist an optimum extruder screw speed that leads to the highest gel fraction and a minimum reaction temperature for the reaction to complete. Nitrogen, phosphorous, and sulfur containing additives can improve the processability of grafted PE, aniline was found to be able to greatly increase the MFR of grafted of PE without significant decrease of gel fraction.