Effect of Reinforcer Percentage and Its Distribution on Mechanical Behavior of Alumina Reinforced Epoxy Composite

In this paper, the shear and tensile properties of alumina reinforced epoxy composite have been studied. For this purpose, the composite samples were first produced with different weight percentages of alumina particles (10 to 50 percent). Then, the shear punching test was used for the evaluation of the shear and tensile properties of composite samples; the dispersion and distribution of alumina particles, interface of particles/ matrix, and the fracture surface of the samples were examined by the scanning electron microscope (SEM) equipped with EDS analyzer. The results of the tests showed that by the addition of alumina up to 30 percent resulted in homogenous and uniform distribution as well as more shear strength of composites. But, when the rate of the reinforcer exceeds 30 percent, the rate of the aggregation of the particles increases and consequently the composite strength is reduced. Also, a significant difference was observed between the fracture surface of pure epoxy and that of composites. Unlike pure polymers, the fracture surface of the composites reinforced with alumina (up to 30 percent) was more uneven, denoting an increase in the surface roughness due to the crack path deflection. Fracture in the reinforced composites with a percentage higher than 30 percent has again taken place due to the rate of low wetting of alumina particles with epoxy resin in particle-particle contacts.