Properties of rice husk/epoxy composites under different interfacial treatments

The comparison on the NaOH and 3‐glycidoxypropyltrimethoxy silane (GPS) modifications on the rice husk/epoxy composites was made to improve the interfacial interaction between epoxy resin and rice husk. An optimum concentration of NaOH at 6 wt% or GPS at 10 wt% was found based on the highest performance of mechanical properties at 70 wt% rice husk content. As for the effect of rice husk content, the maximum reinforcing effect was found at 50 and 70 wt% of rice husk with NaOH and GPS treatment, respectively. This was attributed to the increased surface roughness after NaOH modification and silane interaction to enhance the interfacial reaction of rice husk for stronger adhesion, as evidenced by the morphology observation. The highest reinforcement and thermal stability was observed for GPS‐modified cases. Silane treatment gave the lowest glass transition temperatures for the investigated cases due to the flexible alkyl group. For the water absorption property, GPS‐modified cases conferred the lowest level in comparison with that in both unmodified and NaOH modified composites. This was mainly attributed to that the hydrophilic hydroxyl groups were reduced through the reaction of silanol/epoxy groups on GPS and hydroxyl groups on the rice husk, which again echoed the significance of silane surface treatment. POLYM. COMPOS., 38:1992–2000, 2017. © 2015 Society of Plastics Engineers