The team of researchers led by Dr. Poovathinthodiyil Raveendran from the University’s Department of Chemistry has made the sizing and desizing process eco-friendly by using liquid and supercritical carbon dioxide instead of water, and sucrose octaacetate in place of starch.
Sizing also removes or smoothens the projecting microfibres that might interfere with the weaving process.
Traditionally, starch mixed in water is used for the sizing process, and this requires plenty of water.
The researchers used liquid carbon dioxide as solvent and tested three agents that easily dissolve in carbon dioxide for sizing both cotton and polyester yarn.
Suitable agent “Of the three agents tested, we found sucrose octaacetate produced the best results,” says Dr. Raveendran.
But no drying is needed when liquid carbon dioxide is used as it is an inherently dry process.
Once the weaving is completed, the sizing agent has to be completely removed from the yarn as it might resist dyes and chemicals commonly used in textile processing.
In the conventional desizing process, large volume of water is used for desizing or washing the fabric to remove the sizing agent from the yarn, which generates lots of waste water.
Instead of water, the researchers used supercritical carbon dioxide for desizing.
As in the case of sizing, the yarn (in the fabric) becomes dry almost instantaneously when the pressure of carbon dioxide is reduced to gas phase pressure after desizing.