Study On Toughening Modification Of Polypropylene

In this thesis,PP/CaCO₃,PP/talc/CaCO₃ and PP/CaCO₃/POE composites by one-step method and masterbatch method were studied systematically.We put great emphasis on the discussion of the influence of CaCO₃ particle diameter,surface modification,different inorganic particle compound ratio,and the type of carrier-resin of masterbatch on the composites' mechanical properties such as impact strength,tensile strength,thermal resistance and theological property.Differential scanning calorimetry(DSC) and scanning electron microscopy(SEM) were used to analyse the relation between the structure and properties of the composites.In research of PP/CaCO₃ composites,CaCO₃ particles can toughen PP.Surface modified micro-CaCO₃ can reinforce and toughen PP,when masterbatch content is 5%,the tensile strength and impact strength of composites were increased 4%and 114%respectively than pure PP,as the meanwhile,the heat temperature deformation(HDT) is higer than pure PP. PP/PP-g-MAH were used as matrix resin of masterbatch,and when ratio was 1/1,the reinforced and toughened performance was the best.The ratio of talc/CaCO₃,and the composite technique were studied.The results showed that talc and CaCO₃ can make synergistic effect to composites,at a proper ratio,they can reinforce and toughen PP;the composites made by masterbatch method had a better comprehensive mechanical properties than that made by one-step method.To surface modify talc and CaCO₃ particles,then made masterbatch at the ratio of 3/2(talc/CaCO₃). Using this masterbatch to blend with PP,when its content was 5%,the composites' tensile strength was increased 14%,impact strength was increased 104%,HDT was increased 16.1℃than pure PP respectively.The DSC results showed that composites' melt point was no obviously changed comparing with pure PP.Inorganic particles acted as nucleation agent in PP,they can increase the crystallizing temperature and accelerate the crystallizing rate.The SEM results showed that micro-CaCO₃ was dispersed well in PP,which promoted the matrix undergo shear yielding rather than brittle fracture.The composites gained good reinforcing and toughening performance.POE and CaCO₃ also had synergistic effect to PP.When the ratio of PP and POE was proper,the composites can gain good toughness.