Study On The Preparation And Properties Of Surface Modified Nanoparticles/PP Composities

Polypropylene ?PP? is one of the most widely used general plastics. The surface modified nanoparticles are benefit improving the strength, toughness and thermal stability of polypropylene, so they are often used to prepare composites with polypropylene.In this paper, the surface of nano-SiO2 was modified with KH550 and KH570, and the surface of nano-CaCO₃ was modified with NDZ105 and NDZ201. Then we used infrared spectroscopy ?IR? to investigate modified nanoparticles. PP/SiO2/KH550, PP/SiO2KH570,PP/CaCO₃NDZ105 and PP/CaCO₃/NDZ201 composites were prepared by melt mixing process. We investigate the composites by mechanical performance test, thermogravimetric analysis ?TGA?, differential scanning calorimetry ?DSC? and scanning electron microscope?SEM?.The mechanical performance test of the composite showed that the surface modified nanoparticles could increase the tensile properties and flexural properties of PP. The study found that the optimum content of modified nano-SiO2 was 6%. Compared with PP, the tensile strength, breaking elongation and flexural strength of PP/6%SiO2/KH550 could be increased by 22.4%, 13.1% and 16.3%, and the tensile strength, breaking elongation and flexural strength of PP/6%SiO2/KH570 could be increased by 53.4%, 35.5% and 35.2%. The study found that the optimum content of modified nano-CaCO₃ was 2%. Compared with PP,The tensile strength, breaking elongation and flexural strength of PP/2%CaCO₃/NDZ105 could be increased by 55.2%, 24.2% and 17.3%, and the tensile strength, breaking elongation and flexural strength of PP/2%CaCO₃/NDZ201 could be increased by 42.2%, 15.5% and 9.6%.By using TGA to detected the composites, it was indicated that, compared with PP, the TGA curves of the surface modified nanoparticles/PP composite was moved to high temperature, and the T5 of the composite was significantly improved. When the content of modified nano-SiO2 was 6%,the thermal stabilities of PP/SiO2/KH550 and PP/SiO2/KIH570 were the best. When the content of modified nano-CaCO₃ was 2%, the thermal stabilities of PP/CaCO₃/NDZ105 and PP/CaCO₃/NDZ201 were the best.By using DSC to detected the composites, it was indicated that the well-dispersed surface modified nanoparticles can increase the crystallinity and crystallization temperature of PP, and it can promote the formation of ? crystal. The improvement of the crystallinity of PP can help to enhance the tensile strength and flexural strength of the materials, and the ?crystal can improve the toughness of the materials.By using SEM to observe the tensile fracture surfaces of the composites, it was revealed that the uniformly well-dispersed nanoparticles can make PP generate more plastic deformations. Then it can block the deformation of microcracks and enhance the strength and toughness of the composites when the composites were subjected to external stress. However,adding excessive nanoparticles to PP matrix result in agglomeration of nanoparticles,and it can bring about the mechanical properties of the composites becoming worse. In addition,the dispersion of nanoparticles also affected the thermal stabilities of the composites. If the nanoparticles dispersed uniformly,the T5 of the composite was also relatively higher.