Effect of glycerol and short sisal fibers on the viscoelastic behavior of wheat flour based thermoplastic

Wheat flour based thermoplastic having glycerol content (20%, 23%, 25%, 30% and 35% w/w) were fabricated using extrusion followed by compression molding. Dynamic mechanical analysis (DMA) has been done with reference to the amount of glycerol, sisal fiber loading, frequency and temperature. Two transitions peaks were observed for the, matrix, one at low temperature, due to the molecular dynamics associated to glycerol rich phase, and another at high temperature attributed to the molecular relaxation of starch rich phase. By changing the amount of glycerol, it has been observed that, at all temperature ranges, a plasticization effect which concerns mainly in the starch rich phase. Introduction of sisal fiber (up to 10% w/w) increases the storage modulus of the thermoplastic matrix. The peak height of damping curves (tan δ) was lowered as the fiber content. The activation energy was calculated from the maximum temperature (Tmax) of damping curves.