Abstract: The surface of calcium carbonate(CaCO3) was firstly pretreated with maleic anhydride(MAH) to introduce active double bond groups, then grafted chemically by polypropylene wax(PPW) via in-situ solid phase grafting to increase its compatibility with polypropylene. Three kinds of modified CaCO3 with different chemical grafting ratio of PPW were prepared by changing experimental conditions, and their PP-based composites were produced. The effects of interfacial interaction between CaCO3-MAH-PPW and PP matrix on the strength of PP-based composite filled with modified CaCO3 were studied. The results show that the dispersibility of CaCO3-MAH-PPW in PP is improved, suggesting an improved compatibility between them. With the improvement of grafting ratio of PPW on the surface of CaCO3, the interfacial interaction between CaCO3 and PP increases gradually. When the grafting ratio of PPW is 4.48 mg PPW/g CaCO3, the interfacial interaction between CaCO3 and PP is strongest and the decrease of tensile strength of composites is the least, the young′s modulus increases most at the same time. When m(PP)∶m(CaCO3)=100∶50, the young′s modulus reaches 0.86 GPa, which is the 1.63 times of PP′s. When the grafting ratio of PPW is 2.49 mg PPW/g CaCO3, the interfacial interaction between CaCO3 and PP is suitable and the notch impact strength of composites improves the most. And when m(PP)∶m(CaCO3)=100∶10, its notch impact strength is 3.91 kJ/m2, which is the 1.35 times of PP′s.

Key words: polypropylene, calcium carbonate, solid phase grafting in-situ, interfacial interaction, material strength