Structure-property relationship of carbonized needlepunched nonwovens for electromagnetic interference shielding and ohmic heating applications

The structure-property relationship of acrylic and Kevlar fibre derived activated carbon fabrics was investigated for electromagnetic interference shielding and joule heating applications. The single stage carbonization and physical activation of acrylic and Kevlar needlepunched nonwoven fabric was carried out under the modified atmosphere of charcoal layer and nitrogen gas to have gradual reaction with atmospheric air. The effect of 800 degrees C, 900 degrees C and 1000 degrees C carbonization temperature on structural and functional properties was studied. The acrylic-derived activated carbon fabric was found to provide higher carbon yield, less dusting tendency, better mechanical and electrical properties; however poor flexibility and shrinkage properties as compared to Kevlar derived activated carbon fabrics. The formation of more micropores, higher graphitic structure, higher degree of crystallinity, and large surface area was observed in case of both the activated carbon fabrics with rise in carbonization temperature. Furthermore, the activated carbon fabrics derived at 1000 degrees C exhibited greater electromagnetic interference shielding in high as well as low frequency regions. Lastly, the ohmic heating of carbonized Kevlar fabric showed rapid heating, high electric heating efficiency and faster cooling performance but at increased voltage of 5 V than 3 V of carbonized acrylic fabric.