Mechanical properties of epoxy composites with plasma-modified rice-husk-derived nanosilica

In this study, we explored the use of rice-husk-derived nanosilica (nSiO(2)) as fillers in epoxy resins. The nSiO(2) was irradiated with a capacitively coupled 13.56MHz radio frequency (RF) plasma using an admixture of argon (Ar) and hexamethyldisiloxane (HMDSO) or 1,7-octadiene (OD) monomers. The plasma-polymerized nSiO(2) was loaded at various concentrations (1-5%) into the epoxy matrix. Surface hydrophobicity of the plasma-treated nSiO(2)-filled composites increased, which is attributed to the attachment of functional groups from the monomer gases on the silica surface. Microhardness increased by at least 10% upon the inclusion of plasma-modified nSiO(2) compared with pristine nSiO(2)-epoxy composites. Likewise, hardness increased with increasing loading volume, with the HMDSO-treated silica composite recording the highest increase. Elastic moduli of the composites also showed an increase of at least 14% compared with untreated nSiO(2)-filled composites. This work demonstrated the use of rice husk, an agricultural waste, as a nSiO(2) source for epoxy resin fillers. (C) 2018 The Japan Society of Applied Physics