Study On The Properties Of Thoughening And Strengthening Of Polypropylene With Muscovite And Low Density Polyethylene

Polypropylene is one kind of general purpose plastics, which is used widely in plenty of applications, such as chemical industry, mechanical appliance, electric power and transportation. But it also has deficiency, such as low toughness, especially lower toughness at the low temperature. And as structure material, polypropylene's rigidity inferior to engineering plastic. So polypropylene composites are the best material which modified by thoughening and Strengthening, which might be used more widely in plenty of applied fields, even more, which might play the role of engineering plastics in some applied fields.In this article, low density polyethylene was selected as thoughening agent, and muscovite as reinforcements and PP-g-MAH was selected as compatilizer Blending technology was used in preparing PP composites which has appropriate properties. The properties of thoughening and strengthening of polypropylene with muscovite and low density polyethylene was systematically studied. And the mechanism of thoughening and strengthening of composites was probed elementarily. Through above researches, some conclusions could be taken as follow:(1) On the base of pre-evaluation of effect of modification with the method of active exponent and wettability contact angle, the modification effect of muscovite modified by isopropyle tri(dioctylpyrophosphate) titanate was better than methacryloxypropyl trimethoxy silane. On the base of evaluation of properties of composites, the modification effect of isopropyle tri(dioctylpyrophosphate) titanate was also better.(2) On the basic of the orthogonal experiments, the appropriate compounding ratio of composites can be confirmed. The appropriate compounding ratio of PP/muscovite /LDPE/PP-g-MAH was100/10/10/20.(3) On the basic of three single factor optimizing experiments, the optimum compounding ratio of composites can be confirmed. The optimum compounding ratio of PP/muscovite /LDPE/PP-g-MAH was 100/10/6/20. Compared with pure PP, the properties of composites was better, the flexural strength, notched impact strength, Rockwell hardness, melt flow rate, and the Vicat softening temperature were all improved, increased 11.1%,13.2%,31.3%,91.89% and 0.64% respectively. But the tensile strength and the flexuraYoungs modulus had a little decreased. Through above analysis, the properties of composite could be improved, such as thoughening, strengthening, fluidness and heat-resistant, which modified by muscovite and low density polyethylene.(4) Compared the affect of properties of composites with different granularity, appropriate granularity was D₉₀=16.26μm. And compared the affect of properties of composites by different blending process, composites' properties by two-stage blending process is not better than one-stage blending process, only some properties were improved a little, other properties were decreased in different degree. So, the appropriate blending process is one-stage blending process.(5) By the means of scanning electronic microscope and TG-DSC, some researches on mechanism thoughening and strengthening could be obtained. The results show that the thoughening of composites owe to fill muscovite and LDPE, which could minish the crystalloid size as well as debase the crystallinity of polypropylene, and increase interactional effect of two interfaces between the matrix and dispersoid. Besides, the muscovite filled into composites also would increase the strengthening of composites. So the mechanism of thoughening and strengthening of composites is owing to the effect of LDPE cooperating with muscovite. Otherwise, filled with muscovite, the properties of heat-resistant of composite could be improved, and the heat-decompound of composites could be retarded.