Study On The Pretreatment Of Starch With CHPTMA For Improving The Sizing Property Of Grafted Starch Sizes

In order to raise the grafting efficiency and improve the properties of grafted starch used as warp sizing agents, corn starch was subjected first to quaternization and then to the graft polymerization of quaternized starch (QS) with acrylic acid (AA). By introducing positively quaternary ammonium onto starch through the quaternization, graft polymerization reaction of quaternized starch with AA was carried out in aqueous medium using Fe2+-H2O2 initiators to synthesize quaternized starch-g-PAA (QS-g-PAA) for warp sizing. Furthermore, the properties of QS-g-PAA sizing agents were studied and the internal relationship between sizing performance and molecular structure of QS-g-PAA sizes was revealed.A series of QS with different degrees of substitution (DS) were prepared first by using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTMA) as etherifying agent, and then QS-g-PAA with different quaternization level were synthesized in aqueous medium using Fe2+-H2O2 initiators. The influence of the quaternization level on the grafting efficiency, adhesion to fiber, film properties, and desizability of QS-g-PAA were explored. The investigation demonstrated that the mechanical properties of the sized yarns and desizability of QS-g-PAA were studied by comparing with starch graft acrylic acid (S-g-PAA). The pretreatment could increase the grafting efficiency and improve sizing properties. The higher value of quaternization was able to raise the grafting efficiency. The adhesion-to-fibers increased as quaternization level of starch rose, and thus increasing the mechanical properties of size film. Desizability of QS-g-PAA was well.To find desirable parameter in molecular structure of QS-g-PAA for ameliorating its sizing properties, a series of QS-g-PAA with different grafting ratio(Rg) were synthesized via varying the amount of monomer charged. The influences of Rg on the viscosity and viscosity stability of cooked starch paste, adhesion to fiber, and film properties of QS-g-PAA were studied. The experimental results showed that viscosity stability of cooked starch paste became stable. With the increase of grafting ratio, the adhesion of starch to fibers rose, the breaking elongation of QS-g-PAA film increased, but the strength of starch film and the time required for breaking the film in water decreased. Grafting ratio for the QS-g-PAA used as warp sizes was appropriate in 6.2%?8.5% after taking the results of grafting efficiency, adhesion-to-fibers, and film properties into overall consideration.For examining the effect of starch quaterization on sizing property and desizability of the grafted starch, The S-g-PAA size and QS-g-PAA size with quaterization level of 0.036 was adopted in sizing and desizing tests. The mechanical properties of the yarns sized with QS-g-PAA were better than those with S-g-PAA. The desizability of QS-g-PAA size met the requirements of printing and dyeing operation.