High-Performance EMI Shielding Materials Based on Short Carbon Fiber-Filled Ethylene Vinyl Acetate Copolymer, Acrylonitrile Butadiene Copolymer, and Their Blends

The composites of carbon fiber with EVA, NBR, and their blends have been made by melt mixing technique. Stress-strain plots of different composites show that the necking phenomenon is increasing with the increase in fiber concentration in the polymer matrix. The scanning electron microscopic analysis and swelling study exhibit poor interaction between the short carbon fiber and polymer matrix. The decrease in DC resistivity with the increase in short carbon fiber concentration has been explained on the basis of percolation theory. EMI SE increases slightly with the increase in frequency of electromagnetic radiation but increases sharply with the increase in fiber concentration. EMI SE also depends on blend composition and increases with the increase in EVA concentration in the blend. Return loss is decreasing but absorption loss is increasing with the increase in fiber loading. A linear relationship is observed between the EMI SE and thickness of the composites. The EMI SE is found to increase exponentially with the increase in conductivity of the composite. The permeability value is decreasing with the increase in frequency as well as fiber loading. Thermal properties of the composites have been evaluated by thermogravimetric analysis and dynamic mechanical analysis. POLYM. COMPOS., 32:1790-1805, 2011. (C) 2011 Society of Plastics Engineers