Preparation And Thermal Properties Of Epoxy-based Composites

Thermal conductivity of materials widely used in the national economy and defense. Because of the excellent properties such as resistance to chemical corrosion easy to process and mold、anti-fatigue and electrical insulation properties, ploymer instead of metal to become a major thermal conductivity material. However the thermal conductivity of polymer is very poor. How to improve it have became the important research topics.High thermal conductive epoxy composites were prepared by cast molding process. We mainly researched the formulations of composites and compared some typical equation of thermal conductivity of the composite. Details were as follows:1. We discussed the main components, compared different polymer matrix (E-51and E-44epoxy) and different filler (Al2O3, SiC whiskers, SiO2). The results showed that the polymer matrix of low viscosity is conducive to the infiltration of filler, so it can improve the thermal conductivity of composite material indirectly. The higher thermal conductivity of filler would lead to higher thermal conductivity of composite when filler had same size and shape. The larger the size, the higher the thermal conductivity of filled composites, for the same kind of inorganic matters. The arrangement of filler in matrix was affected by the shape of filler greatly. Our study showed that thermal conductivity of composites was higher when we used irregular SiO2. The composite with every kind of filler have the same law:the composite would improve when the amount of filler increases.2. Curing agent (JA-1and#593) and coupling agent(phenyltrimethoxy-silan and KH560) were discussed as additives. Through the comparison of JA-1and#593, air gap could be reduced when we used the curing agen t#593which had curing reaction in room temperature. The less air gap would lead to higher thermal conductivity. We analyzed and compared the filler’s surface when filler were treated by different coupling agents. Both of the coupling agents could successfully coat the filler Al2O3. When the mass fraction of phenyltrimethoxy-silan was3%, the thermal conductivity of composite were higher than the other ratio. The thermal conductivity of composite were higher when the mass fraction of KH560was8%. For the two kinds of coupling agents, KH560has better modification effect to filler.In this paper, the formula is:E-51+25wt.%#593+150wt.%Al2O3+8wt.%×150wt.%KH560, The thermal conductivity of composite were1.2W/(m·K).3. Coefficient of thermal expansion, dielectric properties, and bending strength were be discussed in this paper. The results indicated that the coefficient of thermal expansion of the Al2O3/E-51system is reduced with the increase amount of filler. The calculated values of the mixed-law model were consistent with the experimental data. For the system, the dielectric constant increase with the increase amount of alumina. Maxwell Ⅱ2Garnett and Jaysundere equation were predict the dielectric constant of the Al2O3/E-51system. The right amount of alumina could improvie the bending strength of compisite.4. Compared several classic thermal conductive model of composite with granular filler and the experimental data of Al2O3/E-51composite. Some typical thermal conductive equation of composite with fibrous filler were contrast with experimental data of composite which composed by SiC whisker and E-51. The results show that the calculated data of the series-parallel model and the experimental data is the closest.