Effects of starch acryloylation on the grafting efficiency,adhesion, and film properties of acryloylated starch‐g‐poly(acrylic acid) for warp sizing

In order to enhance the grafting efficiency of graft copolymerization of granular cornstarch with acrylic acid (AA) for improving the adhesion and film properties of starch‐g‐poly(acrylic acid) used as sizing agent, the esterification of hydrolyzed starch with acryloyl chloride was applied before graft copolymerization. The influence of three common initiators on the copolymerization were also studied. The initiators included ceric ammonium nitrate [Ce(NH₄)₂(NO₃)₆], hydrogen peroxide/ferrous ammonium sulfate [H₂O₂/FeSO₄ · (NH₄)₂SO₄], and potassium persulfate/sodium bisulfite [K₂S₂O₈/NaHSO₃]. It was found that acryloylation of starch before the copolymerization was an effective method for substantially enhancing the grafting efficiency and improving the performances such as adhesion‐to‐fibers and mechanical properties of grafted starch film. The acryloylation could increase the efficiency to 67–81% when the degree of substitution (DS) of acryloylated starch ranged from 0.010 to 0.036. The adhesion to polyester and cotton fibers reached their maximum at DS = 0.010 and 0.022, respectively. Strong and tough film was obtained when the DS value was in a range of 0.010–0.022. H₂O₂/FeSO₄ · (NH₄)₂SO₄ redox system was more appropriate for initiating the copolymerization of acryloylated starch with AA.