Estimating the Degree of Mercerization using Near-Infrared Spectroscopy

A consistent degree of mercerization is very often a necessary prerequisite in cotton fabric preparation prior to dyeing. A rapid method of measuring the degree of mercerization was developed by use of a near-IRdiffuse reflectance technique which does not require any sample preparation. It is shown in the x-ray diffraction study that the modification of the cellulose crystal lattice occurs during mercerization due to the conversion of cellulose Ito cellulose II. This morphological change in the cellulose probably affects the O-Hgroup which is involved in hydrogen bonding in the cellulose chain. The near-IRspectra of the cotton cellulose exhibited a noticeable modification in the O-Hstretching first overtone band as a consequence of mercerization. A predictive model regression equation, which includes the wavelength at 1445 nm, has been developed. The near-IRinstrument-determined mercerization indices showed an excellent correlation with the barium activity number when r2was equal to 0.98.