Rice husk as bio-source of silica: preparation and characterization of PLA-silica bio-composites

Silica powder has been extracted from rice husk, employing a simple extraction procedure for preparing poly(lactic acid) bio-composites with differ filler contents (namely, 5, 10, 20 and 30 wt.-%). These materials have been obtained through a semi-industrial process of extrusion. The thermal, mechanical and morphological properties have been investigated. In spite of a broad distribution of silica particle size, the prepared bio-composites have exhibited improved storage modulus and reduced oxygen permeabilities. The collected values at 10 and 30 wt.-% have been compared with those of homologous samples prepared using a commercial silica. Two micro-mechanical models (Voigt and Halpin-Tsai) have been used to fit the mechanical data, as well. Finally, an economic analysis of material and energetic costs has been performed on samples containing silica from rice husk in order to establish if the proposed process is sustainable or advantageous.