Development of new additives for comfort improvement of wrinkle free cotton
Despite the constant increase in the production of synthetic textiles, cotton based textiles still dominates the apparel industry due to unique properties such as water absorption and its soft hand. Over the past few decades textile industry has been looking for environment friendly solutions for producing non-iron cotton products. Cotton is chemically modified to confer permanent non-iron properties. The hydroxyl groups of cellulose polymer chains present in cotton are able to be cross-linked and then fixed for a long time. Evidently, this reduction of hydroxyl group leads to the diminution of moisture absorption as well as softness properties. Additionally the cross-linked cellulose becomes very stiff and loses its tensile and tears properties. To thwart these side effects, co- additives (lubricants, hydrophilic and hydrophobic agents) are usually added during the cross-linking process. As these additives are not chemically bound to the cellulose, they are often washed away after few laundries. The hydrophilic additives are washed off from the fabric quickly as compared to the hydrophobic additives, thus leaving the fabric somewhat quite hydrophobic. The resulting hydrophobicity adversely affects the comfort properties of the cotton garments. Thus the main objective of this project is to develop solutions to overcome the side effect arising from the incorporation of co- additives introduced during the crosslinking process. To solve this problem, we have followed three possible paths.
In the first approach, syntheses of new reactive hydrophilic additives were successfully
performed. Six type of PEG based derivatives were synthetized with different properties (reactivity
and water affinity) and analyzed by FT-IR and NMR spectroscopy. These molecules could be grafted on the cellulose chain during the cross-linking process which leads to improvement in the moisture retention properties of the treated fabric. The main criteria for design of such molecules were its compatibility and stability for the existing crosslinking process. The second approach was to replace the lubricant (PE emulsions) added during the
crosslinking process by amphiphilic polymers which could give hydrophilic behavior to the cotton fabric while offering lubrication for cross-linked cellulose molecules. Stable emulsions of amphiphilic polymers ( PE-co-PEG)have been prepared and incorporated during the crosslinking process. In the third approach, a post treatment of the cross-linked fabric was carried out using hydrophilic polymers to be able to be grafted to the cellulose, these polymers need good absorption by the fiber and good reactivity toward the remaining hydroxyl groups.
In order to evaluate the efficiency of above mentioned approach, various moisture management tests were also carried out. These tests provide quantitative values on the fabric moisture absorption behavior of the cross-linked cotton. Interesting results have been obtained for the second approach and varying results were noticed for the post treatment approach. Experiments for first approach are ongoing and preliminary results are expected soon. Detailed experiments for all approach are being carried by the industrial partners for suitable commercial implementation.
As an outlook to this research, novel functional PEG based additives could find application and usage in other fields such as biomolecules immobilization and drug delivery.