Abstract
The high calorific value of rice husks has elevated its reuse as an energy source; however, the burning of these shells generates a waste ash from rice husk ash (RHA), which makes its disposal a concern. Despite advances, biodegradable polymers are not yet able to compete with those of traditional thermoplastics, which have lower production cost and higher performance. Based on this background, this paper studies the feasibility of reuse of RHA as filler in polymer matrices replacing the conventional filler. This study consists of applying different percentages of RHA in the formulation of polyhydroxybutyrate composite (PHB) and the use of talc (TA) for comparison purposes as conventional filler. The composites used in this assay were obtained by twin-screw extrusion and injection molding of the polymer plus the fillers under study. Physicochemical and biodegradability properties of the composites were evaluated. The composite PHB/RHA was superior in the biodegradability tests and the properties remain practically unchanged in the presence of the filler. Thus, composites with RHA are promising because they take an abundant residue combined with degradation capacity of the polymer, therefore reducing cost and the environmental impact.
Highlights
The production of soil-lime bricks and the results showed biodegradable polymers are still not able to compete that the bricks met the standards required for components with traditional thermoplastic materials that meet the of masonry, regarding unconfined average compressive market demand especially due to low cost and superior strength, individual strength and water absorption[13]
It was observed that the samples with rice husk ash (RHA) showed higher water absorption depending on time when compared to polyhydroxybutyrate composite (PHB) or PHB/TA (Figure 1)
This fact allows the formation of voids, greater than 5% RHA in polymer matrix of composites, facilitating water penetration and absorption by the ash grains because of its porous nature, evidenced in studies in which rice husk ash was used as adsorbent material for dyes[22,23]
Summary
The objective of these studies was to obtain and evaluate composites of polyhydroxybutyrate (PHB) using rice husk ash (RHA) as filler in different percentages, as well as the use of talc (TA) as conventional filler for comparison purposes. The properties of biodegradability and physico-chemical characteristics such as swelling, chemical stability and permeability to water vapor were evaluated, to provide a possibility of economy using RHA.
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