Rheological properties of printing pastes and their influence on quality-determining parameters in screen printing of cotton with reactive dyes using recycled polysaccharide thickeners

Alginate, carboxymethylated guar gum and carboxymethylated cellulose, used as thickeners in printing pastes for monoreactive dyes, were recycled from wastewater concentrates (separated by ultrafiltration from wastewater after screen printing of cotton), and from printing paste residues (obtained from the cleaning of printing equipment and application systems in the printing machine). The printing performance, using original and recycled polymers, was studied via rheological properties of printing pastes and quality-determining parameters of printing. A quantitative interpretation of the flow and the viscoelastic properties, which are strongly connected to the qualitative parameters of printing, was obtained using rheological models (Cross and Friedrich\u2013Braun model). Recycled thickeners are easily reused for screen printing of cotton with monoreactive dyes, provided that the printing paste recipe fits a rheological constraint of equal viscosity in the steady shear conditions

A study of rheological and molecular weight properties of recycled polysaccharides used as thickeners in textile printing

Polysaccharide thickeners (alginate, carboxymethylated guar gum and carboxymethylated cellulose) used for the preparation of printing pastes, were recycled from printing paste residues and from wastewater concentrates, which were separated by ultrafiltration technique from wastewater after screen printing of cotton with reactive dyes. Concentrated aqueous polysaccharide solutions were studied via rheological measurements under steady and oscillatory shear conditions. A satisfactory fitting of viscosity data is obtained with the Cross equation and mechanical spectra are described with satisfactory approximation with the Friedrich\u2013Braun model. The obtained parameters enable a quantitative interpretation of the changes in rheological properties. Moderate changes produced by thickener recycling on the shear-thinning and viscoelastic behaviour of polymers are a direct result of changes in molecular weight averages (MWA) and molecular weight distribution (MWD)