Study Of Morphology And Properties Of PP/EPDM/Nano-CaCO₃ Ternary Composites

In this paper,polypropylene(PP)/ethylene-propylene-diene terpolymer(EPDM)/nano calcium carbonate(nano-CaCO₃) ternary composites were prepared by two step compounding route,in which nano-CaCO₃ and EPDM were mixed first,and then melt blended with pure PP.The dynamic mechanical properties of EPDM/nano-CaCO₃ masterbatch and the relationship beween the morphology and the properties of the PP ternary composites toughened by masterbatch composed of EPDM and nano-CaCO₃ were studied systematically.The key works and conclusions were listed as following:1.The influences of the dosage of nano-CaCO₃ and the mixing time on the dynamic mechanical properties of EPDM/nano-CaCO₃ masterbatch were characterized by dynamic mechanical analyzer(DMA). The results showed that dynamic mechanical performance of the masterbatch being mixed for 15 min with about 70wt%nano-CaCO₃ was excellent at room temperature.When the masterbatch of nano-CaCO₃ and EPDM was dispersed in the PP matrix,these particles could dissipate lots of energy by collaborative deformation of nano-CaCO₃ agglomerate and EPDM,fibrillation induced by interfacial debonding and inducing PP shear band between disperse phase,which markedly improved the toughness of PP/EPDM/nano-CaCO₃ ternary composite.2.The influence of the surface properties of nano-CaCO₃ on the mechanical properties,fracture morphology,rheological behavior and crystallization behavior of the PP ternary composites was studied. Synergistic toughening effects of EPDM and nano-CaCO₃ on PP matrix were discussed.When the composite is subjected to external force,on the one hand,there is an synergetic effect on toughness of PP ternary composites between EPDM and nano-CaCO₃ as the binary masterbatch occurres,on the other hand,cavity formed by dispersed phase-matrix debonding,fibrillation at the interface and plastic deformation of PP can absorb lots of energy.In addition,the shear yielding of PP matrix can be induced and promoted by the void induced by interfacial debonding between nano-CaCO₃ agglomerate and PP matrix,which markedly improved the toughness of PP/EPDM/nano-CaCO₃ ternary composite.3.Distribution of nano-CaCO₃ in PP ternary composites at different mixing time was studied.Migration phenomena were discovered.Sheared field of the polymer fluid in internal mixer was simulated by using POLYFLOW software.The influence of shear strength on nano-CaCO₃ distribution was studied.