Eco-innovative coloration and surface modification of woven polyester fabric using bio-based materials and plasma technology

• Natural coloring species from the root of madder (Rubia tinctorum L.) were used for coloration of polyester, both in a dye and pigment form.
• Very good fastness properties were achieved through exhaustion dyeing with madder dye.
• Coloration by padding process was improved by fabric surface pre-treatments.
• The best pre-treatment was plasma treatment followed by bio-surface modification using chitosan, which improved both hydrophilicity and adhesion.

Coloration and surface modification of woven polyester (PET) fabric with bio-based materials and plasma technology have been researched for the development of “greener” textile wet processing.Natural coloring species from the root of madder (Rubia tinctorum L.) were used for coloration, both in a dye and pigment form, and the coloration of PET was explored both through mordant free exhaustion dyeing and a continuous padding process applied after PET fabric surface modification.The influence of the main dyeing conditions (dyebath pH, dyeing temperature and dyeing time) on exhaustion dyeing performance, as well as the influence of fabric surface modification(s) on the coloration performance by the padding method, was explored. The surface modifications were based on air atmospheric plasma treatment and/or deposition of chitosan bio-polymer.The coloration was evaluated by measuring the color yield (K/S) and the durability properties of the colored samples. The PET surface treatments were characterized by capillarity and zeta potential measurements.Optimum dyeing conditions were reached at pH 5 with a dyeing temperature of 130 °C for 45 min. The most favorable PET surface for coloration by the padding method was obtained with a pre-treatment combination, namely fabric surface activation by plasma treatment before chitosan deposition.This combination increased both wet pick-up and madder adhesion and indeed, a madder colored PET fabric with hydrophilic properties was obtained. Increased zeta potential and increased capillary uptake, in the presence of chitosan with a prior surface activation of the fabric using plasma treatment, would explain the interesting coloration results.Generally, the madder dye was superior to the madder pigment for bio-based coloration of PET and an interesting alternative to synthetic dyes for PET.