Rheological studies of mixed printing pastes from sodium alginate and modified xanthan and their application in the reactive printing of cotton

Abstract

The rheology of printing pastes using sodium alginate and modified xanthan as mixed thickeners has been measured by steady shear tests and dynamic strain sweep tests. The rheological results showed that, with a small addition of modified xanthan to sodium alginate, the flowability of the mixed printing pastes was better than that with sodium alginate alone. Subsequently, as the addition of modified xanthan increased, the apparent viscosity at low shear rates increased gradually, and the mixed printing pastes gained increasingly pronounced shear‐thinning features. In addition, the mixed printing pastes with more sodium alginate exhibited mainly viscous behaviour under strain, and the liquid‐like features became increasingly weak with the addition of modified xanthan. On the other hand, the mixed printing pastes with more modified xanthan exhibited mainly elastic behaviour within the linear viscoelastic region, and the solid‐like features became increasingly marked with the addition of modified xanthan. Mixtures of sodium alginate and modified xanthan can be used as thickeners in the reactive printing of cotton, producing a good colour yield, levelness, and outline sharpness. In particular, for large patterns, the mixed printing paste performed best when the ratio of sodium alginate to modified xanthan was 80:20; for fine patterns, it performed best when the ratio of sodium alginate to modified xanthan was 20:80.