Studies On A Green And Novel Starch-based Textile Sizing

Polyvinyl alcohol (PVA), acrylic acid and starch are the three major sizing agents which used in textile industry. PVA and acrylic acid are non-environmentally friendly textile sizing which are hard to be biodegraded. In this work, polyurethane prepolymer (PUP) was synthesized and mixed reactively with starch in an internal mixer to prepare modified starch, and then green textile size was prepared with modified starch. Modified starch was compression molded in a hot press, the wet sheets were cut into strips for tensile testing. The results show that the toughness of the modified starch sheets significantly increased, the breaking elongation of the starch modified with polyurethane (CP10) sheet was 5.62% and that of the raw starch was only 2.68%. The thermo-bonding stability of modified starch emulsion was also greatly improved, the thermo-bonding stability value of raw starch was 77%, which of modified starch was above 90%. Polyester-based polyurethane modified starch has better adhesion to spun polyester yarn, the adhesivity of starch emulsion to polyester was 103N, which of CP10 emulsion was 118N. Compared with pure starch size mixture, the sizing performance indicators of modified starch were increased, indicating that it is possible for modified starch with polyurethane as green textile size.In addition, polyurethane prepolymers were synthesized using different molecular of polyols, and then used to prepare modified thermoplastic starch sizing agents. The warp properties of various Mw of polyurethane soft segments on the structure of the modified starch sizing agents were investigated. Results showed that compared with pure starch, flexibility of the modified starch sizing were improved. With the decreasing molecular weight of soft segments in PUP, the NCO content of PUP would increase, and the compatibility of hydrophobic polyurethane and hydrophilic starch was improved due to increasing number of urethane bonds. The compatibility of the interphase was important for improving the property of starch based materials. Therefore, the polyurethane modified starch sizing film has better breaking elongation which was synthesized using molecular weight of 600 polyols. The polyurethane modified starch sizing has lower viscosity and better viscosity stability which was synthesized using the molecular weight of polyols. Polyurethane modified starches have no obvious change for the adhesion to polyester yarn which was synthesized of different molecular weight of polyols.