Structural, thermal, rheological, morphological and mechanical properties of thermoplastic starch obtained by using hyperbranched polyester polyol as plasticizing agent

Abstract

In this work, the effect of the proportion of a hyperbranched polyester polyol (HBP) of fourth generation on the structural, thermal, rheological, morphological and mechanical properties of tapioca starch/HBP blends (TPS) was evaluated. For this purpose, the ratios of starch:HBP employed to prepare the TPS were: 30:70 (TPS30), 40:60 (TPS40) and 50:50 (TPS50). Using infrared (IR) analysis, it was observed that the presence of HBP produced a displacement at the absorptions of the C-OH, C-O and C-O-C bonds of the TPS. The X-ray diffraction (DRX) analysis showed that the starch crystallinity is A and B type, which increased with the HBP amount. The glass transition temperature (Tg) of the TPS, increased with the HBP content, but the thermal stability and viscosity (at an angular frequency of 1 Hz) presented an opposite behavior. The scanning electronic microscopy analysis (SEM) revealed that the granular structure of the starch was not completely destructured.