Preparation and Toughening Modification Research of Silver Plating Copper Powder/EVA Electromagnetic Shielding Plastics
Electromagnetic shielding plastics with different mass fractions were prepared by melt blending three kinds of silver-coated copper powder(Ag@Cu)with ethylene-vinyl acetate copolymer(EVA).The effects of different mass fractions and particle sizes of Ag@Cu on the electrical conductivity,shielding properties and mechanical properties of EVA-based electromagnetic shielding plastics were investigated.EVA-based electromagnetic shielding plastics were toughened by maleic anhydride grafted ethylene-octene copolymer/ethylene-octene copolymer(POE-g-MAH/POE)toughening masterbatch and polyisobutylene(PIB)/terpene toughening masterbatch,respectively,to obtain highly filled electromagnetic shielding plastics.The results show that with the increase of Ag@Cu content,the electrical conductivity of EVA-based electromagnetic shielding plastics increases,while the mechanical properties decrease.The percolation threshold of the composites decreases with the increase of filler particle size.When the Ag@Cu filling content is 80%,the shielding effectiveness increases with the increase of filling particle size.Compared with POE-g-MAH/POE,the toughening effect of PIB/terpene is the best,the elongation at break is increased to 187.3%,the shielding effectiveness is kept above 70 dB in the range of 30～1 000 MHz,and it shows better extrusion processability.
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