Study On The Structure And Properties Of QS/PVA And OSS/PVA Blend Films

Starch film is brittle and rigid due to the cyclic structure and hydrogen association of starch molecules.In weaving process,starch film existed on the surface of warps easily ruptures and drops from the surface,thereby adversely affecting the weaving ability.It's the main method of increasing the sizing properties of starch through performing starch modification or blending the starch with PVA.In this paper,the quaternary ammonium cationic starch(QS)was synthesized by using 3-chloro-2-hydroxypropyl methyl ammonia chloride as the etherification agent.The octenyl succinate starch(OSS)was synthesized by using octenyl succinic anhydride as esterifying agent.And their blend films with PVA were also made.The tensile properties of the blend films were evaluated in terms of tensile strength,breaking elongation and wear loss.And the influences of degree of substitution(DS)of the modified starches,the molecular structure of PVA and blending ratio on the structure and properties of the QS/PVA blend films and OSS/PVA blend ones were estimated.The structures of blend films were characterized by FTIR,XRD and SEM analysis.In addition,the adhesion and sizing properties of cooked QS/PVA blend pastes and OSS/PVA ones were also studied,respectively.The experimental results show that the structure and properties of the blend films were correlated with both the DS of starch.With the increases in DS values of QS,tensile strength and breaking elongation of the QS/PVA blend films raised,and wear loss of blend films decreased.As degree of substitution of OSS increased,the elongation and wear loss of OSS/PVA blend films decreased,tensile strength increased first and then decreased.The strength of the films reached its maximum value and their porosity were the smallest when the DS value was 0.024.The molecular structure of PVA had significant influence on the structure and properties of the blend films.The degree of crystallinity of starch film could be reduced by blending PVA with starch,thereby improving the toughness and tensile properties of starch film.Increasing the degree of polymerization and alcoholysis of PVA could enhance tensile strength and breaking elongation of the blend films,and decreased their wear loss.The blending ratio has a significant effect on the structure and properties of the blend films.With the increase in PVA content,tensile strength and wear loss of QS/PVA blend films decreased,and their breaking elongation and phase-separation extent increased.Increasing the content of PVA could raise the elongation of OSS/PVA blend films,decreased their wear loss,and make their strength exhibit the trend of decreasing first and then increasing.The strength of the blend films was the smallest and their porosities were largest when the blending ratio was 50:50.The results of adhesion measurement showed that the increases in DS values and PVA content can improve the adhesion strengths of cooked QS/PVA and OSS/PVA blend pastes to cotton and polyester fibers.The experiment results of warp sizing showed that the QS/PVA and OSS/PVA blends could eliminate the hairiness on the yarn surface,and their sizing performances were better than that of acid hydrolyzed starch/PVA blends.Based on the properties of blend films,adhesion and sizing,it was recommended to use QS of DS was 0.032 or OSS of DS was 0.024 with PVA1799 for sizing according to the ratio of 70:30.