engleski

Surface Free Energy of Pretreated Cotton Fabrics

The conventional alkaline scouring of cotton removes noncellulosic hydrophobic material from the primary cell in the outermost zone of cotton fibers. Noncellulosic substances in primary cell wall are pectic substances and hemicelluloses. Because of several disadvantages of alkaline chemicals it was recently investigated the scouring of cotton by use of pectinase. The purpose of this paper is the study of the surface free energy changes ofm conventionally and pectinase scoured cotton fabric. Desized and unbleached cotton fabric, from Testfabrics. Inc., NJ, (fabric weight 122 g/m2) was used for conventional and alkaline pectinase treatments. The alkaline pectinase is a pectate lyase which catalyses the degradation of pectate salts in the cotton primary cell wall. Pectinase BioPrep 3000L is supplied by Novo-Nordisk, Bagsvaerd, Denmark. Enzymatic treatments was performed in the bath containing 0, 05% (owf) BioPrep 3000L, Triton 100X 0, 2g/L and EDTA 2% (owf), at pH 8, 2 and 60oC, at the liquoe ratio of 20:1 in the Linitest, Original, Hannau. The surface free energy of the solids generally presents the sum of apolar (gLW) and polar (gAB) interactions. The cotton surface is mainly monopolar with an electron donor (Lewis basis) interaction which is the results of the presence of carboxyl end-groups, the apolar interaction can be Lifshits-van der Waals interactions. To determinate the surface free energy components the wicking method adapted to the textile fabric was applied and specific energy charges accompanying the process, DG, were obtain. The paper discusses results of free energy components for penetration of deionized water, formamide and n-heptan. The method is based on the spontaneus penetration of liquids into porous surfaces of cotton fibers in a closed chamber made from Plexiglas. For this purpose one set of the cotton strips was conditioned (precontacted strips) in the saturated vapour of n-heptane, water or formamide and another set were measured in the air conditions (bare strips). The thin-layer wicking technique modified by Chibowski et al. was applied. For all experiments pure desized cotton fabric from Testfabrics. Inc., NJ, (fabric weight 122 g/m2) was used.

cotton fabric; pretreatment; surface free energy

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