Thermal properties and degradation kinetics of epoxy-gamma-alumina and epoxy-zinc oxide lightweight composites

Lightweight composite materials are the gold standard in aeronautical and aerospace applications due to their strength and low mass. To transport higher payloads and reduce launching costs, nanosatellites, an excellent option for space exploration due to their lightweight structures, are migrating to composite materials. Nanosatellites, also known as CubeSats, must resist high thermal radiation loads while working in orbit. Polymer-based composite materials maintain low mass and the incorporation of reinforcing ceramic fillers contributes to increasing radiation and heat resistance, meeting both requirements. In this work, the effects of gamma-alumina (Al2O3) and zinc oxide (ZnO) micro- and nanoparticles on the thermal properties and degradation kinetics of epoxy-based composites were investigated. The effective thermal conductivity improved up to 17.8 % for epoxy/gamma-Al2O3 and 27.4% for epoxy/ZnO. The effective thermal diffusivity values show a monotonic decreasing behavior as a function of the particle concentration for the epoxy/gamma-Al2O3 composites while for the epoxy/ZnO composites, no correlation on the effective thermal diffusivity values with the ZnO-content was observed. Both oxide-based ceramic fillers increase the thermal stability of epoxy up to 250 degrees C; however, gamma-Al2O3 decreased the maxima decomposition temperature of the epoxy matrix by 6 degrees C. Zinc oxide did not affect the maxima decomposition temperature but decreased the activation energy of epoxy by 45%. These results provide a feasible manufacturing method for epoxy-based composite materials (i.e., nanosatellites) where efficient heat transfer, heat resistance, and low mass are required.