Adhesion-to-fibers and film properties of etherified-oxidized cassava starch/polyvinyl alcohol blends

In our previous work, it was demonstrated that etherified-oxidized cassava starch (EOCS) showed greater adhesion and film properties than oxidized cassava starch (OCS). Therefore, the purpose of this paper is to reveal if blending EOCS with polyvinyl alcohol (PVA) could further enhance the adhesion of OCS to cotton and polylactic acid (PLA) fibers and toughen OCS film. The EOCS samples were synthesized through etherification of OCS with 3-chloro-2-hydroxypropyl sulfonic acid sodium in an aqueous medium, and were characterized by Fourier transform infrared spectroscopic technique. The apparent viscosity of cooked EOCS/PVA paste was measured, and the adhesion was evaluated by measuring the bonding forces of the blends to cotton and PLA fibers. Film properties were analyzed in terms of tensile strength, breaking elongation, bending endurance, scanning electron microscopy and X-ray diffraction. It was found that blending EOCS with PVA was able to further enhance the adhesion of OCS to both fibers and toughen OCS film. The enhancement in the adhesion and the film toughness was correlated with blending ratio of EOCS to PVA. With the decrease in the ratio, the breaking elongation and bending endurance of the blend films and bonding forces significantly increased. By increasing the degree of substitution (DS) of EOCS, the bonding forces of EOCS/PVA blends to both fibers gradually increased. In the adhesion, the positive influence performed by the ratio is more than that performed by the DS. The EOCS/PVA with a ratio of 50:50 and a DS of 0.031 could be adopted to further improve the adhesion and film toughness of OCS.