Investigation of Mechanical and Thermal Properties of Silica-Reinforced Epoxy Composites by Using Experiment and Empirical Model

Abstract

In this study, the mechanical and thermal properties of epoxy composites that are reinforced with micrometer-sized silica particles were measured and evaluated by using the experiments and empirical numeric models. For all specimens used in this study (from the baseline to specimen containing 70 wt% silica filler), the tensile strength and Young’s modulus were gradually increased by 8-10% and 51-55%, respectively, but the ductility of the specimen was decreased by 34%, compared with those of the baseline samples. Similarly, for the samples containing 70 wt% silica filler, the coefficient of thermal expansion was reduced by 25%, but the thermal conductivity was increased by 100%, compared with those of the baseline samples. The improvement of thermal stability of the silica-reinforced specimen was confirmed to be within the experimented range, and the smaller silica particle was found to be more effective in delaying the thermal expansion of the specimens. When the smaller particle was used as filler, due to the increased specific interface area between filler and matrix, the thermal conductivities of the composite specimens were measured to be slightly lower than those of the specimens reinforced with the larger particle. The comparison of the experimental results with those of the empirical numeric models demonstrated that a reliable model for predicting the Young's modulus of composite specimens needs to account for certain property variations in the composites in addition to volume fraction changes in the filler and matrix.