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Abstract
Polyester fabrics were exposed to an atmospheric pressure plasma jet (APPJ) to improve their detergency performance. Surface characterization of the polyester fibers showed that wettability, surface free energy, and surface oxygen concentration increased after the APPJ treatment. The untreated and APPJ-treated polyester fabrics were soiled with carbon black, oleic acid, and stearic acid as model contaminants. The soiled fabric was washed together with the original fabric in the aqueous detergent solutions without and with mechanical action (shake or ultrasound). A washing test using a horizontal drum type washer in accordance with ISO 6330 was also performed to verify the efficiency of the APPJ treatment to polyester fabric in a domestic laundry. The soil removal from the fabric and redeposition onto the fabric were evaluated from the changes in the surface reflectance of the soiled and the original fabrics due to washing. As expected, the APPJ treatment was found to enhance soil removal and to prevent soil redeposition independent of detergent solution and mechanical action. When the polyester fabric after soiling was exposed to the APPJ, the increase in soil removal and the decrease in soil redeposition were remarkably observed compared with the APPJ exposure to polyester fabrics before soiling. Such detergency improvement by the APPJ was also observed for a cotton fabric soiled with stearic acid.
Keywords
Atmospheric pressure plasma jet, polyester fabric, detergency, soil removal, soil redeposition
Polyester textiles have many excellent properties, such as high strength, good stretchability, durability, and easy-care features. However, soils deposited on polyester surfaces are difficult to remove through conventional laundering owing to their high hydrophobicity. Therefore, yellowing and graying of polyester fabrics often take place after repeated wearing-washing cycles.1 To overcome these disadvantages, polyester products have been treated with chemicals to generate reactive functional groups on the fiber surface.2-6 Recently, oxidation of polyester fiber surfaces by plasma or ultraviolet light exposure in gas phase have been extensively performed.7-12 RF-plasma and vacuum-UV surface activation have been also utilized as pretreatment for preparation of self-cleaning textiles.13-17 Detergency is a surface-dependent property and therefore can be improved by altering a very thin surface region of the polyester fiber. From this viewpoint, plasma and UV treatments can enhance detergency without affecting the bulk properties of the polyester material.
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