Effect of fixation conditions on yellowing behavior of cellulose powder–coated fabrics

In this study, the yellowing behavior of cellulose powders, which is applied to pretreated polyester woven fabrics with concentrations of 100 g/kg by knife coating technique, was investigated. After drying process, coated fabrics were cured at different conditions to determine the effects of the curing temperature and time on yellowing behaviors. The yellowness–whiteness of coated fabrics was measured with a spectrophotometer according to ASTM E313. As the curing temperature and time increase, yellowing effect was more observable. However, the effect of temperature increase is found to be more significant than the increase in curing duration in terms of more observed yellowness. In order to investigate the reason of yellowing, cellulose powder samples were heated in drying oven at three different heating temperatures (130°C, 150°C, and 170°C) for three different heating periods (3, 5, and 7 min). Then, thermal gravimetric analysis and Fourier transform infrared spectroscopy analysis of powder samples were performed for each temperature–period combinations. No ring-opening reaction on the cellulose group was found in the Fourier transform infrared spectroscopy analysis. However, the changes in the spectra can be attributed to the chain breakage in the cellulose macromolecules as well as water loss from the molecular structure during the heating process. Microscopic and scanning electron microscopic analysis was carried out to see any surface change on the fiber and coated fabric. There was no detectable surface change on the fiber and coated fabric surface, apart from a color change on the fabric surface.