Silane Cross-linked Polyethylene And Its Nano-montmorillonite Modified

With dicumyl peroxide (DCP) as initiator, vinyl triethoxy silane (VTES) as monomer, dibutyl tin dilaurate (DBTDL) as catalyst, the thesis chooses different Polyethylene(PE) to study saline cross-linking of polyethylene(PEX) in the two-screw extruder. The effects of technics on the properties of PEX were studied, such as the kind of PE, the dosage of DCP and VTES, cross-linking reaction time and temperature, screw rotational speed. PEX has good performances and has been used to production of the aluminum-plastics compound pipe already.On the basis of above research, nano-montmorillonite (n-MMT) modified PEX was studied. Three dispersed methods was investigated, they are melt blending intercalation, mastbatch intercalation and solution intercalation. The structure of n-MMT in the polymer matrix was studied by means of TEM,SEM, XRD. The effect of n-MMT to crystallinity of PE by DSC and the content of n-MMT in matrix to the properties of PEX matrix was studied. The result showed that PEX/MMT nanocomposite was prepared through mastbatch intercalation is a feasible method and n-MMT can be intercalated by molecule chain of PE. This method use PE grafted MAH as carrier resin to prepare n-MMT mastbatch in the two-screw extruder. Mastbatch melt with PE grafted VTES and prepare PEX/MMT nanocomposite in the two-screw extruder. Compared with PEX, PE grafted VTES matrix has better yield strength, yield module, heat stability, and worse elongation rate, the gel fraction of PEX matrix decrease. When the content of n-MMT between 3 % to 5 %, PEX/MMT nanocomposite has better properties than PEX.