Thermomechanical improvement of glycerol plasticized maize starch with high loading of cellulose, flax and talc fillers

For the purpose of extending the applicability fields of thermoplastic starch (TPS), a study on their properties with high filler loadings was performed. Two different organic natural reinforcements (cellulose and flax) and a typical mineral filler (talc) were incorporated in TPS using melt blending. The resulting composites were observed on fragile fracture surfaces by scanning electron microscopy to study the filler/matrix adhesion. Magnifications revealed good TPS−fibre interfacial interac t ion with limited debonding. The thermomechanical properties by dynamic mechanical thermal analysis (DMTA) and the correlation with the filler amount (from 10 to 50 wt%) were thoroughly investigated at 50% relative humidity and 23°C. The tests evidenced a huge increase in composite storage moduli (E′) of more than 200% with respect to the neat matrix. Moreover, the resulting DMTA experimental data were interpolated with the Cox − Krenchel micromechanical model. To this aim, the necessary measures of the filler dimensions were calculated after the extrusion process on water-dissolved residues using an optical microscope. This model was able to correctly follow the experimental results also at high filler loadings.