Study On Grafting Modification Of Polypropylene And Chlorinated Polypropylene

Polypropylene (PP) is one of the most promising thermoplastic polymer. However, the use of polypropylene has been restricted because it is a kind of non-polar polymer. In order to improve its property, polypropylene should be modified. Polypropylene is modified by chlorine to obtain the chlorinated polypropylene (CPP) which is used widely in industries. However, the properties of CPP which exists in domestic market have some defects so that its application is still limited .The properties defect include poor adhesive, low transmissivity and easy changing color which must be overcome so as to improve its properties for fitting the need of coating, printing ink and adhesive.PP modified by means of melt grafting maleic anhydride (MAH), MAH and styrene (St) is studied by a double-screw extruder on the conditions with adding the assistant and without any assistant respectively. The technological conditions for melt-grafting are optimized by orthogonal experiment. The influences of amount of MAH, St, DCP and the assistant on the grafting ratio, degradation and cross linkage are investigated and influential factors are analyzed. Structure of the products is characterized by Fourier transform infrared spectroscopy (FTIR). Grafting ratio (G) is determined by titration analysis, degree of degradation is determined by melt index (MI), and degree of cross linking is determined by gel ratio(Ge). The mechanism of MAH grafting PP, and side reaction of PP are analyzed The mechanism of cross linking of PP is put forward to. The degradation and cross linking of PP restrained by the assistant is analyzed also.The experimental results show that the assistant can reduce the degradation and cross linking of PP and improve the grafting ratio of MAH. The properties of modified PP by double monomers and the assistant are improved further and its application enlarges.The chlorating of polypropylene and maleic anhydride -polypropylene ( MAH-g-PP) is carried out at different reaction conditions. The effects of reaction temperature, reaction time, flow rate of chlorine, PP concentration and initiator benzoperoxide (BPO)concentration on the chlorating degree are studied. The optimum technological conditions are obtained. The mechanism of chlorating modification of isotactic PP is analyzed. The...