Study of Properties of Biodegradable Composites of Starch/Gluten/Glycerol Reinforced with Sisal Fibers

Biocomposites using starch/gluten/glycerol as matrix and sisal fibers were produced by melt-mixing in an intensive batch mixer connected to a torque rheometer at 130 C. The samples were compression molded and than characterized by water absorption and mechanical test. In tensile test, the increasing in the Young's modulus and ultimate tensile strenght were respectively of aproximately 560 and 162% in relation to matrix, whereas elongation at break decreased. The storage modulus increased with increasing fiber content whereas tan 8 curves decreased, confirming the reinforcing effect of the fibers. The addition of sisal fibers in matrix decreased the water absorption at equilibrium. The diffusion coefficient decreased sharply with 5% addition of fiber and further sisal fiber additions provoked only small variation. Optical microscopy observations revealed good dispersion of the sisal fibers into the matrix.