Abstract: In order to find environmentally friendly cross-linking agents suitable for the modification of cassava starch used for warp sizing for the purpose of replacing the toxic cross-linking agents commonly used in the production of the starch sizes and meeting the demands of viscosity stability of the cooked starch pastes to heat during warp sizing operation, a series of cross-linked starch with different degree of crosslinking (DC) were prepared by using non-toxic sodium trimetaphosphate (STMP) as a crosslinking agent through varying the feed ratio of STMP to the starch. Influences of DC on the paste viscosity, viscosity stability, adhesion to fibers, film properties, de-sizing behavior, BOD5 and COD were studied. It was found that the cross-linkage could significant improve the viscosity stability of cooked starch pastes to heat. DC exhibited marked effects on the viscosity, viscosity stability, adhesion to fibers, properties of starch film and de-sizing behavior, but little effect on biodegradability. Experiments demonstrated that the cross-linked starch could meet the demand in the warp sizing if the starch was cross-linked to a DC value of 650 AGU/CL by STMP.

Key words: cross-linked starch, adhesion, cross-linking agent, film, degree of crosslinking