Single fibre coating of cellulose acetate fibres for hydrophilic modification using carboxymethylated starch

Abstract

Hydrophilic bio-based and biodegradable fabrics and fibres can be an alternative to petroleum-based fabrics and fibres. Hydrophilic modifications of conventional textile structures by compositing can be introduced on a fabric as well as on a fibre level. Here, the coating of hydrophobic cellulose acetate multifilaments with carboxymethylated starch (CMS) pastes is reported. The CA fibres were drawn through starch preparations with varying degrees of substitution for coating. To ensure CMS anchorage, citric acid was added to cross-link the hydrophilic starch preparation itself and to the substrate. Cross-linking and CMS gel viscoelasticity were determined using a heated FT-IR stage and a rheometer respectively. The composites were also characterised for citric acid elution, as their degree of swelling in water vapour. As the amount of crosslinker increased, the gel viscoelasticity increased, but so did the citric acid elution in swelling media. Through several drying and swelling steps, the hydrophilic CMS structures lose their swelling ability. Coated fibres were also tested in a fine wash. The hydrophilic coating is depleted.An estimate of the chemical consumption for the production of such composites is given and compared with related approaches. As the chemical modification only affects the sheath, the chemical consumption can be reduced.