Study On Properties Of Talc,Diatomite Modified PP Composites

In this paper, the effect of talc or diatomite as filler and nucleating agent on the properties of homopolymerized PP (PP-H) and copolymerized PP (PP-B) was systematically studied by means of melt blending. The effect of content, particle size, surface activation, etc. of talc on mechanical properties, heat resistance, crystallization properties, microstructure, etc. of PP was investigated. Meanwhile, the effect of content and surface activation of diatomite on mechanical properties, heat resistance, crystallization properties and microstructure of PP was researched. Furthermore, POE-g-MAH was used in the toughening modification of PP/Talc which optimal formula has been determined previously and a kind of PP composite with low cost, good heat resistance, high toughness and low decrease in strength was obtained. The summary of the conclusions are listed as follows:Mechanical properties of PP/Talc composites decreased with the increase of particle size of talc, heat resistance changed little by the change of particle size. Among these different types of talc, SL-3005 Talc with D50 of 3.86um had the best modification effects on comprehensive performance of PP.The filling modification influence of talc on the mechanical properties and heat resistance of PP-H was similar to its effect on PP-B and the strength and impact toughness of PP were improved by talc at the same time. PP-H/Talc had more excellent heat resistance, strength and rigidity, whereas the toughness of PP-B/Talc was better. Talc had better modification effects on heat resistance of PP-H than PP-B, which the best filling content was 10phr, the vicat softening point increased by 6.2?, and the heat deflection temperature increased by 20?.Properties of modified PP filled with activated talc were significantly better than those modified by unactivated talc, and the optimum dosage of KH570 was 1.5% of mass of talc during the activation. The notched impact strength, bending strength, vicat softening point and heat deflection temperatur increased by 71%,58.2%,7? and 28.8? respectively as the best filling content of activated talc was 15phr.The modification effect of diatomite on mechanical properties of PP was bad. The modification effect of activated diatomite was a little better than that of the unactivated diatomite, but not obvious yet. Diatomite can improve the heat resistance of PP.Talc and Diatomite were both able to play the role of heterogeneous nucleation on PP. The crystallinity increased by 6.8% and crystallization peak temperature increased by 8.1? as the best filling content of talc on the nucleating modification of PP was 0.3phr.While the crystallinity and crystallization peak temperature increased 4.2%,6.1? respectively as the best filling content of diatomite on the nucleating modification of PP was 0.4phr.When compared with pure PP, PP/Talc/POE-g-MAH composites with the optimum formula of 100/15/5 achieved the best comprehensive performance which notched charpy impact strength increased by 164.5%, bending strength increased by 13.2%, vicat softening point increased by 4?, heat deformation temperature increased by 21.4? and tensile strength decreased by only 1%. A kind of PP composite with good heat resistance, high toughness, low decrease in strength and low price was obtained.