Equivalent Thermal Conductivity of Epoxy Composites Filled with Aluminium and Red Mud Particles

Abstract

The present research deals with the effect of volume fraction of filler particles on the effective thermal conductivity (keff) for polymer composites. This work sees an opportunity of enrichment of heat conduction ability of a typical particulate filled polymer composite. A mathematical correlation for the of polymer composites filled with elliptical shape particles is developed using the law of minimal thermal resistance and equal law of the specific equivalent thermal conductivity. To validate this mathematical model, two sets of epoxy based composites, with filler content ranging from 0 to 25 vol % have been prepared by simple hand lay-up technique. For first set, micro-sized aluminium particles are chosen as filler whereas for second set red mud is taken as a filler material whereas matrix material remains epoxy. Thermal conductivities of these composite samples are measured as per ASTM standard E-1530 by using the Unitherm™ Model 2022 tester. Experimentally measured values are then compared with the values obtained from the proposed mathematical model and also with models established earlier such as Rule-of-Mixture (ROM), Maxwell’s model, and Bruggeman model. It is observed that the results obtained from the proposed model fits well with the experimental data. This study shows that the keff improves quite significantly as the conductive filler in the composite increases. An improvement of about 160 % in the value of thermal conductivity is recorded with addition of 25 vol % of aluminium filler in epoxy resin whereas when filler material is red mud it is noticed that keff increases by about 135 %. From this point of view a costly aluminium powder can be replaced by an industrial waste red mud powder as far as thermal conductivity is concerned.