Rheological, dynamic mechanical and transport properties of compatibilized starch/synthetic copolymer blends

Abstract

The method of mechanical activation due to shear stress in the rotor-stator device (RSD) was used to combine the gelatinized starch and the latex of the styrene-acrylic copolymer (SAC). The influence of composition and method of mechanical activation on the rheological behavior of the aqueous starch/SAC blends, as well as on the dynamic mechanical properties, water sorption and salt transfer of the films was studied. A decrease in the starch content in water mixtures and joint activation were shown to promote a decrease in their viscosity and consistency index in the Ostwald-deWaele equation. The temperature dependences of the storage modulus (E′) and the mechanical loss tangent (tanδ) were obtained at tension of the starch/SAC films. An increase in E′ and a decrease in tanδ with increasing starch content have been established. Anomalous rise in rigidity was noted as the result of introduction of 20% SAC in starch. The increase in starch content is accompanied by a marked decrease in the rate and a rise in the equilibrium degree of swelling. An increase in the starch content from 20 to 80% results in a ninefold increase in the NaCl permeability coefficient.