Effect of backbone moiety in epoxies on thermal conductivity of epoxy/alumina composite

We chose two commercial epoxies, bisphenol A diglycidyl ether (DGEBA) and 3,3,5,5-tetramethyl-4,4-biphenol diglycidyl ether (TMBP), and synthesized one liquid crystalline epoxy (LCE), 44-bis(4-hydroxybenzylidene)-diaminophenylene diglycidyl ether (LCE-DP) to investigate the effect of backbone moiety in epoxies on the thermal conductivity of epoxy/alumina composite. The DGEBA structure shows an amorphous state and the TMBP structure displays a crystal phase, whereas the LCE-DP structure exhibits a liquid crystalline phase. The curing behaviors of them were examined employing 4,4-diaminodiphenylsulfone (DDS) as a curing agent. The heat of curing of epoxy resin was measured with dynamic differential scanning calorimetry (DSC). Alumina (Al2O3) of commercial source was applied as an inorganic filler. Thermal conductivity was measured by laser flash method and compared with value predicted by two theoretical models, Lewis-Nielsen and Agari-Uno. The results indicated that the thermal conductivity of the LCE-DP structure was larger than that of the commercial epoxy resins such as TMBP and DGEBA and the experimental data fitted quite well in the values estimated by Agari-Uno model. POLYM. COMPOS., 2013. (c) 2013 Society of Plastics Engineers