Study On The Properties Of Polypropylene Modified With Nano-CaCO₃

In this paper the mechanical properties of several grades polypropylene(PP) and nano-CaCO₃ composites are studied. Based process parameters of twin screws and mixer are optimized. Influences of the mechanical properties of PP/nano-CaCO₃ composites prepared by twin screws and mixer are compared. The influence of maleic anhydride grafted PP used as a compatilizer is studied. During the study, the microstructure of nano-CaCO₃ filled polypropylene is analyzed by DSC,POM,SEM,TEM and Ceast impact test machine.The results shows that with the increasing dosage of nano-CaCO₃,the flexural modulus of PP/nano-CaCO₃ composites is improved,while the charpy impact strength reaches the highest when nano-CaCO₃ is about 3%-6%,after that,the charpy impact strength is decreased with the increasing dosage, the toughness of PP composites is increased by the addition of CaCO₃ nano-particles.The optimized process parameters of mixer are mix temperature 165℃,rotate speed 60 r/min,mix time 15min. The optimized process parameters of twin screws are screws temperature 210℃,screws rotate speed 230 r/min,feed-in 50%.The CaCO₃ nano-particles are well-distributed in PP matrix in spite of twin screws or mixer processes.When maleic anhydride grafted PP was used as a compatilizer for the composites, the interfacial compatibility between nano-CaCO₃ and PP was increased by the addition of the compatilizer, and the mechanical properties of PP composites were improved. Elastomer and nano-CaCO₃ has synergistic toughing effect on polypropylene.When PP/nano-CaCO₃ composites is subject to impact force,the PP base body is induced to yield strain by nano-CaCO₃ ,then the impact strength improves.