Preparation And Properties Of Dynamically Vulcanized PP/EPDM/Ni Coated Glass Fiber Electromagnetic Shielding Composites

With the rapid development of information technology,electronic products and telecommunications bring not only great convenience to people's life,but also serious problems of electromagnetic interference?EMI?.Polymer-based EMI shielding materials attracted many researchers due to their low density,design flexibility,effortless shaping and resistant to corrosion.Thermoplastic vulcanizates?TPV?combines the high elasticity of conventional vulcanized elastomers and the good processability and recyclability of thermoplastics,which have been widely used in industries such as automotive,wire and cable,building and medical device.So,it's significant to prepare conductive TPV composite with good EMI shielding performance.In this paper,Ni coated glass fiber?NCGF?with the higher aspect ratio and good conductivity was prepared by electroless plating.PP/EPDM/NCGF electromagnetic shielding composites were prepared by"melt blending and injection molded".On that basis,the effects of thermal aging on the performance of PP/EPDM/NCGF composites were investigated.And ascorbic acid?vitamin C?were used as antioxidant to enhance the thermo-oxidative aging resistance of PP/EPDM/NCGF composites.In addition,a small amount of TiO₂ were doped to PP/EPDM/NCGF composite,and the synergistic effects of hybrid fillers on the electrical conductivity and EMI shielding efficiency of the PP/EPDM/NCCF/TiO₂ composites were investigated.?1?The Ni coated glass fiber?NCGF?with core-shell structure was successfully prepared by electroless plating.The conductivity of NCGF could be as high as 80 S/cm.The conductive PP/EPDM/NCGF composites with good EMI shielding efficiency were fabricated by melting blending and injecting method.The composite exhibits an EMI SE of 26 dB,tensile strength of13.2 MPa and elongation at break of 126.5%by adding 16.36 vol%NCGF?1.0 vol%Ni?.?2?Due to the oxidation of the surface nickel layer for NCGF,the performance of composites were extensively affected.The percolation threshold of composites increased from0.789 vol%to 0.956 vol%Ni content.Although thermo-oxidative aging had a negative influence on the electrical properties and EMI shielding performance of composites.The composite still exhibits an EMI SE of around 22 dB by adding 19.15 vol%NCGF.?3?On that basis,the ascorbic acid?VC?,a powerful antioxidant capable of mopping up free radicals,were selected to relieve the oxidation and degradation of PP/EPDM/NCGF composites.Results show that the melting temperature,crystallization temperature and tensile strength of PP/EPDM TPV has no significantly change after thermo-oxidative aging by adding0.2 phr VC,and its elongation at break increased from 5%to 76.8%.Besides,for the PP/EPDM/NCGF composites with ascorbic acid,the decline rate of EMI SE is only 5%.?4?The synergistic effect of hybrid filler enhances the electrical conductivity and EMI shielding efficiency for PP/EPDM/NCGF/TiO₂ composites,which percolation threshold?Ni content?declined from 0.789 vol%to 0.628 vol%compared with PP/EPDM/NCGF composites.On the basis of commercial shielding effectiveness?20 dB?and an elongation at break value of more than 100%,the NCGF content of composites declined from 16.36 vol%to 13.47 vol%.