Improving the pilling property of knitted wool fabric with atmospheric pressure plasma treatment

Knitted wool fabrics are very easy to pill during wear and use. In this study, knitted wool fabrics were treated with atmospheric pressure plasma (APP), a completely dry treatment, using plasma jet with helium and oxygen as carrier and reactive gas, respectively, under various processing parameters: (i) jet-to-substrate distance; (ii) oxygen flow rate; and (iii) treatment time. This paper reports the study of how these APP processing parameters influence pilling property of knitted wool fabrics. After APP treatment, pilling property of knitted wool fabrics was evaluated by standard testing method for pilling (EN ISO 12945-1; ICI pilling box method). Also, a conventional wet anti-pilling treatment (with an anti-pilling agent) was carried out on knitted wool fabrics in order to compare anti-pilling effect of APP (dry treatment) and anti-pilling agent (wet treatment). Experimental results revealed that the APP treatment can greatly improve anti-pilling performance without adverse effect like yellowing. Scanning electron microscopy revealed that surface etching effect induced by APP treatment could be one of the reasons of improved anti-pilling property of knitted wool fabrics. Various processing parameters provide different degrees of etching on wool fibre surface. Meanwhile, no fabric shrinkage was noted in the APP treated knitted wool fabric but about 5% shrinkage in area was noted in fabric treated with anti-pilling agent.