Behaviour of Fluorochemical-Treated Fabric in Contact with Water
The introduction of fluorinated coatings in the textile industry has improved significantly the hydro- and oleophobic properties of the treated fabrics. However, these properties are notably reduced when the fabric is washed and partially recovered with h
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Abstract. The introduction of fluorinated coatings in the textile industry has improved significantly the hydro- and oleophobic properties of the treated fabrics. However, these properties are notably reduced when the fabric is washed and partially recovered with heat treatment in air such as ironing. These changes of repellency are related to the modification of the chemical organisation of the fiber surface. This paper describes the chemical structure of some of the fluoropolymers used in textile and their relationship with these surface properties. A new explanation of the nature of this diminishing performance in contact with water and its recovery by heating is given.
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lntroduction
The study of the properties of solid surfaces has long involved scientific effort, both theoretical and experimental (Dhathathereyan et al., 2002). Fluorinated compounds such as surface coatings have attracted especially intense research effort in recent years, and much of the motivation for such study comes from the novel physical properties of these coatings, which include high bulk modulus, reduced optical birefringence, and unusually low interfacial tension. V. Starov et al. (eds.), Fluid Mechanics of Surfactant and Polymer Solutions © Springer-Verlag Wien 2004
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A. R. Estelrich
In the textile industry, fluorinated coatings are the most important class of water- and stain repellent finishes due to their ability to provide optimum performance in terms of both hydro- and oleophobicity. They also have additional desirable features such as fire-proofing, without impairment of the textile's permeability to air and vapour or modification of the hand of the fabric (Castelvetro et al., 2001). Consequently, the importance of these coatings in clothing and as engineering textiles is growing. Introducing different monomers within the same polymer can vary and improve their performance. Today's fluorinated coating materials (usually emulsion copolymers of perfluoroalkyl-containing acrylic or methacrylic esters) are replacing the more traditional paraffin waxes and siloxane polymers (Grottenmüller, 1998; Holme, 1993). Because fluorocarbon polymers do not adhere to most nonfluorinated surfaces, special techniques have to be adopted in order to supply sufficient adhesion between the substrate and the coating (Höpken et al., 1992). The adhesion problern can be eliminated copo1ymerising highly fluorinated monomers with non-fluorinated ones. The polymer backhone can be tailored to provide good adhesion to the substrate, while the fluorocarbon segments are not compatible with the hydrocarbon matrix and concentrate at the coating/air-interface. The effectiveness of the surface protection depends on the coverage of the surface with fluorocarbon segments and on the degree of ordering in the surface layer. The performance and durability of modern fabric finishes require improved laundry permanence of water and oil repellent finishes (Juhue et al., 2002). However it is generally documented that water repellence decreases with extensive washin
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