Functionalization Of Polyolefin And Nanocomposites

Polyolefin (including Polypropylene (PP) and Ethylene-propylene rubber (EPR)) is a general purpose plastic and its application fields are very wide. It has many merits, such as the higher yield, lower price, water resistance, chemicals resistance and the simple technological process. In view of no polar and a crystalline polymer the polyolefin is, it is difficult to create superficies, or to brush, or to blend with other polymer and filling matter, so it is difficult to develop the novel polyolefin alloys.First, graftings of polyolefin with maleic anhydride for its functionalization was studied. Maleic anhydride grafting onto polypropylene and ethylene-propylene rubber were prepared by novelty means of pre-irradiation, ultrasoication and co-irradiation. The effects of irradiation dose, ultrasonic intensity, monomer concentration, reaction temperature, and reaction time on the percentage of grafting (G) and grafting efficiency (GE) were investigated. The results show that G is highest by co-irradiation in microsuspention than other means. The crystal degree of PP-g-MAH is higher than PP by DSC and XRD, so did the crystal temperature. But the crystal configuration of main molecule chain is not changed. The percentage of grafting of the products obtained above is 6%. The obtained products by irradiation grafting reaches an advnaced level of the same products of both domestic and foreign countries.In this thesis a kind of silane coupling agents and maleic anhydride (MAH) grafted polyolefin (PO-g-MAH) obtained above were employed as interface compatibilizers for PP/nano-SiO2. PP nanocomposites were prepared by ultrasonic. The composites with different compatibilizers and nano-SiO2 content were characterized by means of mechanical testing, Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Fourier transformation infra-red spectroscopy (FT-IR), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), etc. The relation between the structure and property of the composites was discussed in this thesis. The results show that the PP filled by using nano-SiO2 modified with different interface compatibilizers has better mechanical performances than pure PP. The mechanical properties of the PP/nano-SiO2 modified with silane coupling agent and PO-g-MAH are better than that of the PP/nano-SiO2 modified with solo coupling agent. It is also found that there is some optimum dosage of nano-SiO2 in the PP/nano-SiO2. XRD and DSC were used to investigate the surface treatment and the usage of the nano-SiO2 influencing their crystalline characteristic. Results showed that PP/nano-SiO2 has the same crystal type with the pure PP. So the melt point changes a little. Nano-SiO2 acts as the nucleation agent in PP. The SEM results show that nano-SiO2 is dispersed well in PP, which promoted the matrix undergo shear yielding rather than brittle fracture.