Curing Behavior and Properties of Rice Husk/Melamine Formaldehyde Composites

Melamine formaldehyde (MF) composites filled with rice husk powder were prepared by compression molding. The curing processes of the composites with different powder contents and powder particle sizes were studied by dynamic mechanical analysis. Gelation temperature and curing time were subjected to optimization of their mechanical and thermal properties. The rice husk powder loading in the MF matrix and the powder particle size were found to be critical factors governing the curing behavior and properties of the composite. Composites with larger content or smaller powder size had higher gelation temperatures and lower viscosities. The curing times of the composites were also influenced by the powder content. Flexural strength and flexural modulus increased with powder loading in the 20 to 90 mesh particle size range, while notched impact strength decreased. The mechanical properties of the composites decreased to a considerable extent when the fibers were too small to achieve strong interfacial adhesion. Morphological (scanning electron microscopy) and thermal studies (heat deflection temperature) were also conducted.