Researchers at the Department of Chemistry in Calicut University in Kerala have come up with a new approach to ‘size’ and ‘desize’ cotton and polyester yarns through a dry process using liquid and super critical carbon dioxide (scCO2) and inexpensive sugar acetates that can conserve water in the water-intensive textile industry.
The research has been published in the ‘ACS Sustainable Chemistry & Engineering’ journal, according to a report in a top Indian English-language daily. Sizing is the process of applying a protective adhesive coating on the yarn to strengthen it to decrease breakages on the loom and attain maximum weaving efficiency. Conventional sizing method involves drawing the yarn through a concentrated sizing solution, mostly starch and polyvinyl alcohol, and then drying it.
After weaving, the yarn has to be ‘desized’ by washing with water, which requires up to 2,500-2,1000 litres per 1,000 kg of cotton yarn and drying is an energy-intensive process.
The team studied the possibility of utilising scCO2 as an alternative medium for sizing and desizing using CO2-soluble compounds like sucrose octaacetate (SOA) and two other compounds as sizing agents.
The tensile strength of the yarn was found to have almost doubled for the cotton yarn when sized with SOA, while it rose by 60 per cent for the polyester yarn. SOA could be completely washed off during desizing using scCO2, the study found.