Rheology and morphology of polyester/thermoplastic flour blends

Abstract

International audienceTwo maize flours (standard and waxy grades) were plasticized in an internal mixer with a constant amount of water and two glycerol contents. The resulting thermoplastic flours (TPFs) were characterized in dynamic oscillatory shear and creep/recovery rheometry. They displayed two different behaviors: the viscoelastic behavior of a high-molecular-weight polymer for the first one and a gel-like behavior for the second one. The TPFs were then mixed with a copolyester [poly(butylene adipate-terephtalate)]. All of the blends contained the same volume fractions and were prepared with the same mixing conditions. The morphology and rheological behavior of each blend were characterized. Different morphologies, ranging from cocontinuous to nodular, were observed. In fixed mixing conditions, the blend morphology was shown to be governed by the rheological behavior of the starchy phase and the plasticizer content. The gel-like behavior of the second TPF seemed to prevent droplet coalescence; this led to a very fine dispersion. The rheological behavior of each blend appeared to be linked to both the morphology and the rheological behavior of the two phases

Thermoplastic Starch Composites With Titanium Dioxide and Vancomycin Antibiotic: Preparation, Morphology, Thermomechanical Properties, and Antimicrobial Susceptibility Testing

“…The complex viscosity (|η * |) values of TPS/TiO 2 composites were very high in the entire range of frequencies (Figure 5), in agreement with previous studies (Della Valle et al, 1998;Deme et al, 2014;Ostafinska et al, 2017). The complex viscosities of TPS/TiO 2 exceeded the complex viscosity value for the pure TPS matrix.…”

Loss of crystalline structure and swelling kinetics of maize starch and flour granules in glycerol excess: The role of the envelope structure

“…In plasticized starch and in plasticized starch/thermoplastic blends, where the amount of glycerol is typically 33-36 wt% to see if the difference in the envelope strength can still be detected in compounding conditions. We recently showed that the rheological behavior and the morphology of plasticized flour/thermoplastic blends were determined by the amylose/amylopectin ratio, the plasticizer content and the processing conditions, as for plasticized starch/thermoplastic blends (Demé et al, 2014). Becker et al (2001) studied the influence of a thermal treatment with glycerol stearate on various starches.…”