Improvement of properties of glycerol plasticized starch films by blending with a low ratio of polycaprolactone and/or polyethylene glycol

The effect of the melt blending of polycaprolactone (PCL) (5 and 10 wt. %) and polyethylene glycol (PEG 4000 D) (2 wt. %) with corn thermoplastic starch (with 30% glycerol) on film properties was studied through the characterization of the structural, thermal and physical properties of the films obtained by compression moulding, after 1 and 5 storage weeks. PCL and PEG decreased the glass transition temperature of starch, whereas no changes in PCL melting properties were observed. Starch films could incorporate 5% PCL without a notable phase separation, leading to more stretchable and stable films. Blend films with 10% PCL showed clear phase separation, without any improved tensile properties, but with lower water vapour permeability. In ternary systems, PEG reduced the PCL-starch affinity, enhancing phase separation, whereas it did not improve the film properties with respect to starch films. (C) 2015 Elsevier Ltd. All rights reserved.