Surface Modification of Textiles by Glow Discharge Technique: Part II: Low Frequency Plasma Treatment of Wool Fabrics with Acrylic Acid Bengi Kutlu, 1 Aysun Aksit, 1 Mehmet Mutlu 2 1 Dokuz Eylul University, Textile Engineering Department, Izmir, Turkey 2 Hacettepe University, Engineering Faculty, Food Engineering Department, Plasma Aided Biotechnology and Bioengineering Research Group (PABB), Beytepe Campus, Ankara, Turkey Received 25 February 2008; accepted 15 August 2009 DOI 10.1002/app.31286 Published online 5 January 2010 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: In this study, wool fibers are modified by low frequency plasma polymerization of acrylic acid regarding to its’ hydrophobic character due to cuticular cells at their surfaces. Variables of the plasma glow dis- charge processes were power (40–100 W) and exposure time (5–45 min). The effect of plasma modification in the performance properties of wool were investigated on the basis of hydrophilicity of wool, average wrinkle recovery angle, and breaking strength. The surface chemical struc- tures of fabrics were examined with x-ray photoelectron spectroscopy. The hydrophobic wool fabric became hydro- philic after all plasma treatments except one (40W–5 min). Average wrinkle recovery angle of the treated fabrics were between 157 and 178  , while that of untreated fabric was 180  . The treated fabrics had a little bit lower angles according to the untreated fabric. However, even the lowest value as 157  means that the fabric has a good crease resistance property. The breaking strengths of fab- rics were increased up to 26% after the plasma treatments. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 1545–1551, 2010 Key words: textile; wool; plasma polymerization; modi- fication; ESCA/XPS INTRODUCTION Chemically reactive plasma discharges are widely used to modify the surface properties of materials. Among numerous traditional and new technologies of surface treatments of textiles and films, the plasma treatment is a powerful tool to fulfill envi- ronmental requirements and has very specific func- tions as it exclusively affects the surface, both chemi- cally and physically. Plasma processing technology is very important to several of the largest manufac- turing industries in the world. Plasma-based surface processes are critical for the electronics, aerospace, automotive, steel, biomedical, and toxic waste man- agement industries. Materials and surface structures can be fabricated that are not attainable by any other commercial method, and the surface properties of materials can be modified in unique ways. Surface modification by low pressure plasma treatment illus- trates many important advantages over techniques such as environmental safety, uniformity and repro- ducibility, variety of reagent gases, and selective modification with minimization of bulk property change. 1–4 The outer layer of the wool fiber is the cuticle. The surface of the cuticle cells (epicuticle) contains a co- valently bound fatty acid, the chiral 18-methyl eico- sanoic acid (18-MEA). This fatty acid is probably bound via a thioester linkage. This acid accounts for about 70% of the fatty acids covalently bound to the wool fibre. 5 The epicuticle is highly resistant to attack from alkalis, oxidizing agents, and proteoliytic enzymes. It is about 2.5 nm thick and amounts to approximately 0.1% of the weight of the fiber. The wool fiber exhibits hydrophobic properties due to the presence of this fatty layer, which surrounds each cuticle cell. 3,6–8 Absorption of water to improve the comfort and wear properties of textiles can be enhanced by increasing the hydrophilicity of natural and syn- thetic fibers. Grafting of hydrophilic monomers is used to give hydrophilic properties to textiles by chemical, radiation, and induced reactions. 9–11 Oxi- dative plasma (such as oxygen, water vapor) treat- ments are the other way to give hydrophilicity to textile materials. 12–16 Acrylic acid is well known to give hydrophilicity to materials, which it is applied. 17,18 Although it has been widely used on Correspondence to: A. Aksit (aysun.cireli@deu.edu.tr). Contract grant sponsor: Turkish Scientific and Technical Research Council Project; contract grant number: TUBITAK 105M099. Contract grant sponsor: Dokuz Eylul University, Scientific Research Center, Project No: 05.KB.FEN.050.. Journal of Applied Polymer Science, Vol. 116, 1545–1551 (2010) V C 2010 Wiley Periodicals, Inc.