Characterization of the Surface Properties of Differently Scoured Cotton by Inverse Gas Chromatography at Infinite Dilution

Inverse gas chromatography (IGC) has been successfully used for comparative characterization of the surface properties of alkaline-scoured and bioscoured cotton samples in fibrous form. Under appropriate standard conditions the dispersion component (γ _s ^d ) of surface tension and the electron-acceptor ( K _A ) and electron-donor ( K _D ) constants were determined for characterizing the surface properties of raw, alkaline-scoured and pectinase-scoured cotton. The dispersion component of surface tension increased slightly with increasing hydrophilicity of the surfaces (raw: 39.0 mJ/m ² , bioscoured: 40.0 mJ/m ² , alkaline scoured: 41.7 mJ/m ² , at 30°C), indicating that the wax removal that occurred is somewhat higher in alkaline scouring than in bioscouring. The γ _s ^d values decreased continuously with increasing measurement temperature in the range of 30—70°C (raw: 32.0 mJ/m ² , bioscoured: 33.2 mJ/m ² , alkaline scoured: 35.9 mJ/m ² , at 70°C). Polar probes were not retained on raw cotton at all. The surface of the alkaline-scoured and bioscoured cotton samples was predominantly basic in character: K _D /K _A 6.8 and 8.2, respectively, where K _A and K _D were calculated from the Δ G _A ^ab at 30°C. Despite the weight loss difference (3.2% and 0.7% for alkaline and bioscouring, respectively) and the residual pectin in bioscoured cotton, the results show that the acid—base character of the surface of the alkaline and pectinase-scoured samples is very similar.