Abstract

DEBIAGI, Flávia; MALI, Suzana; GROSSMANN, Maria Victória Eiras  and  YAMASHITA, Fábio. Biodegradable foams based on starch, polyvinyl alcohol, chitosan and sugarcane fibers obtained by extrusion. Braz. arch. biol. technol. [online]. 2011, vol.54, n.5, pp. 1043-1052. ISSN 1516-8913.  http://dx.doi.org/10.1590/S1516-89132011000500023.

Biodegradable foams made from cassava starch, polyvinyl alcohol (PVA), sugarcane bagasse fibers and chitosan were obtained by extrusion. The composites were prepared with formulations determined by a constrained ternary mixtures experimental design, using as variables: (X₁) starch / PVA (100 - 70%), (X₂) chitosan (0 - 2%) and (X₃) fibers from sugar cane (0 - 28%). The effects of varying proportions of these three components on foam properties were studied, as well the relationship between their properties and foam microstructure. The addition of starch/PVA in high proportions increased the expansion index and mechanical resistance of studied foams. Fibers addition improved the expansion and mechanical properties of the foams. There was a trend of red and yellow colors when the composites were produced with the highest proportions of fibers and chitosan, respectively. All the formulations were resistant to moisture content increase until 75% relative humidity of storage.

Keywords : cassava starch; mechanical properties; microstructure; expansion.