A series of starch‐g‐poly(2‐acryloyloxyethyl trimethyl ammonium chloride) (starch‐g‐PATAC) samples with different grafting ratios was prepared via the graft copolymerization of acid‐thinned granular corn starch with 2‐acryloyloxyethyl trimethyl ammonium chloride (ATAC) in aqueous medium using Fe2+–H2O2 initiator. The adhesion of starch‐g‐PATAC to cotton and polyester fibers was investigated for warp sizing. Influence of the positively charged branches grafted onto backbones of starch upon the adhesion was revealed. It was found that the branches showed positive effect on the adhesion. Starch‐g‐PATAC possessed stronger adhesion than its counterpart. Zeta potential, surface tension, and contact angle measurements were performed to find the reason for the alteration in the adhesion. In addition, cooked starch‐g‐PATAC paste was stable in apparent viscosity under high temperature. Using alkali‐oxidant agent desizing, starch‐g‐PATAC was desizable when its grafting ratio was no more than 7.5%. Positively charged branch‐grafted starches showed their potential as size base materials in warp sizing operation.

Abstract This work was undertaken to examine the effect of poly(2-acryloyloxyethyl trimethyl ammonium chloride) (PATAC) branches grafted onto the backbones of starch on the toughening of starch film. A series of starch-g-PATAC samples having different levels of grafting ratio were prepared by the graft copolymerization of granular corn starch with ATAC in an aqueous system, using Fenton’s initiator through changing the weight ratio of the monomer to starch. The influences of grafted branches on the properties such as tensile strength, breaking elongation, work-to-break, bending endurance, moisture regain, swelling power, and solubility of starch film were evaluated by comparison with those of acid-treated starch (ATS). It was found that the branches were able to toughen starch film due to the significant increases in breaking elongation, work-to-break and bending endurance of the film. The branches were also able to increase its moisture regain, water swelling power, and solubility. In addition, the properties were dependent on the amount of the branches. Furthermore, the grafted starch was biodegradable when its grafting ratio did not exceed 7.5 wt%.