Some Studies on HAF Reinforced Epoxy Composites

Abstract

Epoxy composites loaded with different concentrations (5—50 wt%) of high abrasion furnace carbon black (HAF) with and without the addition of 10 wt% Mg(OH)2 were prepared and subjected to electrical, mechanical, flammability, and thermal measurements. It was found that the permittivity ε' and dielectric loss ε'' increased by increasing HAF content. This increase is slightly lowered by the addition of Mg(OH)2. The electrical conductivity of HAF-epoxy composites increased from the pure polymer towards that of pure carbon. A low frequency region with relaxation time τ 1 in the range 3.5—4.5 × 10-4 s is found to be unaffected by either filler content or the presence of Mg(OH)2. The higher frequency range with relaxation time τ2 is nearly the same for lower concentrations of HAF up to 10 wt% (percolation threshold concentration). Above this concentration a dramatic increase was noticed. Incorporation of 10 wt% of HAF led to an increase in the compressive strength value. Further increase in HAF content resulted in a decrease in compressive strength values. The tensile strength values of the composite samples before and after the addition of 10 wt% Mg(OH)2 are higher than that of the unloaded one. The addition of 10 wt% Mg(OH)2 improved both the thermal stability and the fire retardant efficiency of HAF—epoxy composites.