Mathematical model for evaluating effective thermal conductivity of polymer composites with hybrid fillers

• A mathematical model of one dimensional heat conduction has been developed.
• This model estimates the keff of hybrid filler polymer composite systems.
• Model is validated with various experimental results.
• The theoretical and experimental results are in close approximation.

A mathematical correlation for evaluating the effective thermal conductivity (keff) of hybrid polymer composites filled with two dissimilar particulate fillers is developed using the law of minimal thermal resistance and equal law of specific equivalent thermal conductivity. The estimations are validated with experimental results. Epoxy and polypropylene are chosen as matrix materials. Two conductive fillers, aluminium nitride (AlN) and aluminium oxide (Al2O3) and two insulative fillers, pine wood dust (PWD) and rice husk (RH) are chosen as filler in present study. Sets of thermoset polymer composites (epoxy based) and thermoplastic composites (polypropylene based) are fabricated by hand lay-up technique and compression molding technique respectively. keff of all the fabricated composites are measured by Unitherm™ Model 2022 tester as per ASTM E-1530. The measured values are than compared with the values obtained from the proposed mathematical model for 0–15 vol% filler concentration. While there is no theoretical model available in the literature so far for estimation of keff for polymer composites with hybrid fillers, it is encouraging to notice that the measured values are in close approximation with the values predicted by the model proposed in this work.