CONICET | Buscador de Institutos y Recursos Humanos

Polypropylene (PP)composites with 5wt%of different rigid particles (Al2 O3 nanoparticles,SiO 2 nanopar-ticles,Clay (Cloisite20A)nanop articles or CaCO 3 microparticles)were obtained by melt mixing.Compos- ites with different CaCO 3 content were also prepared.The effect of fillers,fillercontent and addition of maleic anhydride grafted PP(MAPP)on the composites fracture and failure behavior was investigated.For PP/CaCO 3 composites,an increasing trend of stiffness with fillerloading was found while adecreasing trend of strength,ductility and fracture toughness was observed.The addition of MAPP was beneficialand detrimental to strength and ductility,respectively mainly as aresult of improved interfacial adhe- sion.For the composites with 5wt%of CaCO 3 or Al 2 O3 ,no significantchanges in tensile properties were found due to the presence of agglomerated particles.However,the PP/CaCO 3 composite exhibited the best tensile behavior:the highest ductility while keeping the strength and stiffness of neat PP.In general,the composites with SiO 2 or Clay,on the other hand,displayed worse tensile strength and ductility.These behaviors could be probably related to the fillerability as nucleating agent.In add ition,although the incorpor ation of MAPP led to improved fillerdispersion,it was dama ging to the material fracture behav- ior for the composites with CaCO 3 ,Al 2 O3 or Clay,as aresult of ahigher interfacial adhesion,the retardant effect of MAPP on PPnucleation and the lower molecular weight of the PP/MAPP blend.The PP/MAPP/ SiO2 composite,on the other hand,showed slightly increased toughness respect to the composite without MAPP due to the beneficialconcomitant effects of the presence of some amount of the bcrystalline phase of PPand the better fillerdispersion promoted by the coupling agent which favor multiple crazing.From modeling of strength,the effect of MAPP on fillerdispersion and interfacial adhesion in the PP/CaCO 3comp osites was confirmed.