Preparation And Properties Of Ultra-High Molecular Weight Polyethylene Suspending Graft Copolymer

Ultra-high molecular weight polyethylene (UHMWPE) has long chain molecular structure to endow polyethylene with excellent dimensional stability and frictional resistance and impact resistance, the melt viscosity is very high for machining, the purpose of this experiment is on the basis of application performance is to ensure that the material itself, the pre-irradiation grafting method is used to improve the molecular chain structure in order to improve the application performance.Experimental methods in air atmosphere, UHMWPE power was irradiated and produced superoxide free radicals as reaction initiator, the suspension grafting technology was used for the grafting of styrene (St) onto the polymer powder subsequently, the styrene-grafted UHMWPE powder was received. These parameters include grafting temperature, the ratio of material, the dosage of auxiliary initiator (BPO), grafting time and grafting atmosphere.The structure of UHMWPE-g-PS was investigated by fourier transform infrared spectroscopy(FTIR),ultraviolet spectrum, nuclear magnetic resonance(’H-NMR) and wide angle X-ray diffraction(WAXD).The FTIR spectra of UHMWPE-g-PS showed some new peaks at3028cm-1,1600cm-1,1495cm-1,757cm-1,696cm-1which are attributed to benzene ring. Ultraviolet spectra of UHMWPE-g-PS showed some new peaks at230nm-270nm, which are attributed to the electron transition of benzene ring in PS.1H-NMR spectra of UHMWPE-g-PS showed new chemical shift peaks at7.138ppm,7.029ppm,6.745ppm,2.026ppm,1.479ppm,1.109ppm which are attributed to the H from benzene ring and-CH2-connected to the benzene ring. UHMWPE showed some X-ray diffraction peaks of crystal face (001),(110),(200), product of the peaks intensity weakening and move to the right compared with the UHMWPE crystal peaks.Properties of material were characterized by means of differential scanning calorimety (DSC), thermogravimetric analysis(TGA), isothermal crystallization curves analysis, tensile property test, rheological behavior of the test, electrical property test, morphology structure of material were investigated by using scanning electron microscope(SEM). The DSC test of UHMWPE-g-PS indicated that the influence of the grafted chain is very complicated for the crystallization process of crystal, the main crystalline phase in line with the avrami equation and the glass transition temperature (Tg) increased, thermogravimetric analysis results showed that UHMWPE and UHMWPE-g-PS have the same thermal stability under the condition of high temperature. The melt flow rate of UHMWPE-g-PS increased, it was showed that the storage modulus(G’)and loss modulus(G ")increased with increasing degree of grafting under the same shear frequency. The breakdown strength, dielectric permittivity and dielectric loss angle of UHMWPE-g-PS increased, the after two values increased with increasing of the content of SiO2. It was found that the tensile strength (σm),yield stress (σy) and elongation at break (εb) of UHMWPE-g-PS/SiO2blends were higher. Scanning electron microscope showed that the fracture surfaces have different grid size of mesh structure of UHMWPE-g-PS and UHMWPE-g-PS/SiO2blends, the fracture surfaces were produced by the ductile fracture way.