Investigation of physical, mechanical, and thermal properties of glass fiber reinforced polymer composites strengthened with KH550 and KH570 silane-coated silicon dioxide nanoparticles

Abstract

Silicon dioxide (SiO2) nanoparticles can be used as reinforcing material for composites due to their favorable characteristics. However, they are commonly subjected to surface treatments with silane coupling agents to achieve fine dispersibility and better mechanical interlocking at interface. In this study, the silane-coated SiO2 nanoparticles (as received) were used as secondary reinforcement without applying additional silane treatment process. KH550 and KH570 silane-coated SiO2 nanoparticles were dispersed, respectively, into polymer matrix, and then the modified matrix was reinforced with glass fibers. Silanized SiO2 filled glass fiber reinforced polymer (GFRP) nanocomposites were investigated for physical, mechanical, morphological, and thermal properties. Depending on the nanoparticles' ratio and silane coating, the increments were obtained till 10% for tensile strength, between 18.40% and 75.26% for flexural strength, and till 81% for impact strength. SEM confirmed that the enhancements could be attributed to the improved interfacial adhesion between the modified matrix and fiber reinforcements. The void contents within the polymer nanocomposites decreased by 38%–54% compared to a pure one. DSC and TGA examinations revealed that silanized SiO2 nanoparticles provided a better curing behavior (10% increase in Tg for 3 wt.% KH550-SiO2) and improved thermal stability for the GFRP composites (increase in Tend values by 50–70°C). Generally, KH550 silane-coated SiO2 has provided enhanced interface strengthening, leading to better characteristics for GFRP composites since the amino functional groups contained in KH550 have more favorable integration with epoxy matrix.