Effects of cellulase enzyme treatment on the direct dyeing and morphological properties of cotton textiles
Abstract
Although the application of cellulase enzymes in the textile industry is quite popular, the morphological changes in cotton caused by the cellulase are not fully understood. The purpose of this research was to study the effects of cellulase enzymes on cotton. More specifically, the goals were to examine the effects of enzyme hydrolysis on cotton's (1) morphological properties such as crystallinity, porosity, and degree of polymerization, and (2) sorption of direct dyes. The influence of surface area on enzymatic hydrolysis was also of interest. Since mercerization is widely known to improve the dyeability of cotton and to change some morphological properties, mercerized cotton was included in this study. Hydrolysis conditions consisted of three enzyme concentrations and four treatment times. Glucose concentration, weight loss, and breaking strength loss increased with increasing enzymatic treatment time and with increasing enzyme concentration. The degree of polymerization decreased with increasing enzyme treatment time. Enzyme treated cotton had the highest crystallinity index (CrI) value and mercerized cotton fabric had the lowest CrI. The increase in CrI for enzyme hydrolyzed cotton was attributed to the decrease of amorphous regions. The higher total pore volume and total surface area found after mercerization concurred with the higher dye uptake of mercerized cotton. Cellulase treatment decreased the total pore volume, particularly in the 10-80A range, and total surface area. Enzyme hydrolysis did not significantly enhance direct dye color yield. The surface area modification study investigated the influence of surface area on susceptibility to enzymatic hydrolysis. The results show that the magnitude of increase in surface area is higher after mercerization than after physical pretreatment, e.g., cutting and milling. These fundamental observations give a practical tool and a practical rationale for enzyme treatment of textiles. The goals of future processing should be to (1) increase amorphous character (use decrystalling enzymes, not hydrolytic ones), and (2) increase the number of 60A or larger pores in the amorphous regions. These guiding features should be useful to the industry as it attempts to optimize new formulations of enzyme reagents for treating cotton textiles.
Degree
Ph.D.
Advisors
Ladisch, Purdue University.
Subject Area
Textile research
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