Rheological and thermal behavior of starch/LDPE blends containing EAA

The composite casts were prepared from native corn starch and low density polyethylene. Ethylene-arylic acid copolymer (EAA) was added as compabilizer and glycerol was added as plasticizer in the formulation. Their rheological and thermal properties were evaluated by capillary rheometry, differential scanning calorimerty, and thermogravimetry analysis. The results show that the viscosity of the blend has an Arrhenius dependence on temperature and a power law dependence on shear rate. The power law exponents (around 0.5) are less than unity, indicating that the melts are shear thinning. The thermal behavior of these materials is evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The water evaporation process observed by DSC in starch is also observed in the blends. Degradation mechanisms of the blends are identified by means of TGA, being assigned to the mass loss due to the plasticizer leaching, and to the degradation of the starch and synthetic polymer fractions. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers