Study of the properties of biocomposites. Part I. Cassava starch-green coir fibers from Brazil

Increasing environmental concerns in recent years focused greater attention on the development of biodegradable materials. This paper presents the preparation of cassava starch based composites incorporating fibers from Brazilian green coconuts. These composites were prepared with different amounts of coir fibers by thermal molding using glycerol as plasticizer for the starch. The matrix and composites were given thermal treatment. Both the untreated and treated matrices and their composites were characterized for their tensile properties, while water uptake, swelling on immersion in water and moisture absorption on exposure to humidity were evaluated for both untreated and treated matrix and its composites. The tensile properties of cassava starch improved with both the incorporation of fibers and thermal treatment. Fractographic studies through scanning electron microscopy were used to explain the observed strength properties. Water uptake, swelling and moisture absorption of TPS showed decrease with the incorporation of fibers, which is due to better interfacial bonding between the matrix and fibers as well as the hindrance to absorption caused by the fibers.