Characterization of cotton fabric scouring by Fourier transform-infrared attenuated total reflectance spectroscopy, gas chromatography-mass spectrometry and water absorption measurements

Abstract

Surface sensitive Fourier transform-infrared attenuated total reflectance (ATR) accessories using different crystals as well as incident beam angles were examined for the characterization of cotton fabric scouring. The extra sharp antisymmetric and symmetric C-H stretching peaks due to long chain alkyls at 2918 and 2849 cm−1 were observed in greige cotton fabrics with a tendency to be more profound with the ATR cell with bigger incident angles and a higher refractive index, due to less depth of penetration. Water absorption data and gas chromatography-mass spectrometry analyses indicated that these peaks were mostly caused by secondary added paraffin wax of higher linear alkanes (C22 to C30) and cotton wax of C16 and C18 fatty acids in free form. Absence of these peaks alone did not result in sufficient water absorption. No observation of carboxylate (COO−) peak at 1600 cm−1 together ensured a successful scouring. Presence of this weak peak can be further confirmed by the reversible shift between 1600 cm−1 and 1750 cm−1 of protonated carboxylic acids (COOH) under non-destructive and quick HCl or NH3 vapor exposures on cotton samples.