Effect of Silane-Coated SiO2 Nanoparticles on the Hardness Values of Glass FRP Composites

Abstract

In this study, silane-coated SiO2 nanoparticles (as-received) were used as secondary reinforcement for glass fiber-reinforced polymer (FRP) composites, and the microhardness values of the developed composites were investigated. The nanoparticles were dispersed within the polymer epoxy at 1.5 and 3 wt.% ratios, respectively. Two different types of silane coating were used that were KH550 and KH570. The mixture of the epoxy resin and nanoparticles were subjected to ultrasonic homogenization to achieve a fine dispersibility of the SiO2 nanoparticles. Then the matrix was prepared with a suitable hardener at a weight ratio of 100:25. The strengthened polymer matrix was reinforced by woven glass fiber fabrics (primary reinforcing element). The vacuum bag method was applied to produce silane-coated nano SiO2 filled glass FRP composites. A digital microhardness testing device was used to determine the Vickers hardness values. While the pure glass/epoxy composite has resulted in a hardness of 20.69 HV, the maximum hardness value was recorded as 36.56 HV and it was obtained with 3 wt.% KH550SiO2 filled glass/epoxy. The incorporation of silane-coated SiO2 nanoparticles has provided dramatic enhancements in terms of microhardness, approximately from 28 to 77%. The microscopic examination was also conducted via an optical microscope and the images were found helpful to explain the test results. Therefore, the findings of this study have shown that silane-coated nano SiO2 filler can be used as secondary reinforcement where high hardness and better wear resistance are desired for glass/epoxy composite applications.