Abstract
This research deals with use of Lee's disc to measure the thermal conductivity and temperature change with respect to time through the thickness of the specimens of the unreinforced epoxy and reinforced epoxy by silica particles at different weight fraction and grain size. The results show that the thermal conductivity increased by increasing the weight fraction and reduced by increasing the grain size of silica particles by nonlinear relationship and the maximum difference between the unreinforced epoxy and reinforced epoxy was (0.445 W/m.ºc) at weight fraction (20 %) and grain size (20 µm) of silica particles, where at this value of weight fraction and grain size the thermal conductivity was maximum value (k= 0.61 W/m.ºc).