The Study Of Modified Polypropylene (PP) Composite For Auto Bumper

In the thesis, the polypropylene (PP) resin was modified for toughness by two methods, Including the adding of POE, blending with nucleators to modify the crystallization of PP. The properties of PP composite were studied and the result is good.Saturation ethylene-octylene copolymer (POE) produced by DOW chemistry company via ethylene and octylene original position polymerization catalysised by metallocene was adopted, when studying modified PP. The brittle-ductile transition of PP/POE was studied quantitatively, and discontinuous phase particle size, crystallization and mechanical properties of PP/POE were studied as well as and they were investigated by scanning electronic microscope (SEM), polarized optical microscopy (POM), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The results shows that the impact strength and rupture elongation ratio of PP/POE can be increased gradually and tensile yield intension reduced gradually as the adding content of POE, while tensile yield intension can be increased gradually and rupture elongation ratio reduced gradually as the increasing of rate of estension. The content of POE adding into PP(K7926)/POE that matrix ductility is lower while PP/POE blends appearing brittle-ductile transition and the critical matrix ligament thickness (Tc) are higher than PP(K7926)/POE that matrix ductility is higher. The crystallization analysis shows that the crystallization degree of PP was reducted sequencely by adding POE to damage PP molecular chain regulation and hind PP crystallization. The crystallization shape and interplanar distance of PP was not changed by adding POE and there is very good consistency between PP and POE.The influence ofαform(TMA-3, TM-1, HPN-68L) andβform(TMB-5) nucleators on crystallization and mechanical properties of impact co-polypropylene was studied and they were investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). The results shows that TMA-3 and TMB-5 nucleators all improve beginning crystallization temperature to 15.3℃and 12.7℃and crystallization peak temperature to 17℃and 13.7℃, accelerate crystallization velocity of PP, increase crystallization degree of PP, reduce, minish and regulate crystallization form. TMA-3 and TMB-5 all increases tensile intension to some extent. TMB-5 because of it's inducting co-PP to generate moreβcrystal form has more evidently increased impact strength and rupture elongation ratio of PP about 56% and 15% thanαform nucleator(6% and 5%).The PP resin was modified for toughness by multiplicity formulation of POE and nucleators, and the mechanical properties of PP/POE/ nucleators were tested. The results shows that Impact strength and tensile intension can be increased to some extent and combination property is good. The PP composite reach the require of auto bumper.