Effect of Iron Particle Size and Concentration on Thermal Conductivity of Iron/Polystyrene Composites

The present study deals with the thermal conductivity of iron/polystyrene (PS) composites containing iron particles of different sizes: (5, 50, 150, and 250)  $\upmu \mathrm{m}$ , and with different iron concentrations: (0, 5, 10, 20 and 30) mass%. The effects of iron particle size and concentration on the thermal conductivity of iron/PS composites are investigated in the temperature range: (30 to 120)  $^{\circ }\mathrm{C}$ . It was found that the addition of ultrafine iron particles enhances the thermal conductivity of the composites more than that of larger (coarser) particles. The thermal conductivity also increases with increasing temperature and iron concentration. The glass transition temperature was found to increase with decreasing size of iron particles. A correlation between the observed electrical and thermal conductivities of the iron composites as a function of iron particle size is presented. Fitting of some theoretical models results in predictions of smaller values of the thermal conductivity than are the experimental values.