INFLUENCE OF NaOH CONCENTRATION ON EFFECTS OF MERCERIZATION OF COTTON FABRIC

Abstract

Cotton is the most important natural fiber. Cotton products are widely used, primarily as garments and
home textiles. Although the first associations with cotton are the comfort and gentle touch that cotton provides, as
well as the naturalness of the textile itself, it is also distinguished by many other characteristics that have made it
irreplaceable in the lives of people worldwide. Cotton fabric usually has a very soft feel, and depending on the
thickness of the cotton, transparency as well, which further contributes to comfort. When it comes to the practicality
of this natural material, it is reflected not only in the widespread use of cotton for a variety of needs, but also in its
other key properties. Various mechanical and chemical treatments that are routinely applied in the processing of
cotton materials are very important because they improve the properties of fabrics and knitwear. Among various
chemical treatments, mercerization is one of the main processes in improving the properties of cotton products.
Mercerization is the oldest known process of continuous refining of cotton. By mercerization, cotton acquired
refined properties that are resistant to chemical and mechanical treatments, as well as durability in use and care
procedures. The importance of mercerization has recently increased, especially after the processes of high refining
of cotton and its mixtures had been introduced and after the requirements for dimensional stability of fabrics and
knitwear had increased. During mercerization, changes in the microstructure, morphology, and conformation of
cellulose chains occur. These changes affect the hydrophilic and dyeing properties, breaking strength, gloss, and
dimensional stability of the refined product. In this paper, the influence of mercerization procedure on hydrophilic
and dyeing properties of cotton fabric was investigated. In the experiment, the cotton fabric was treated at room
temperature (20 oC) for 90 s in a taut state in a solution of NaOH with a concentration of 260 g/dm3, 300 g/dm3, and
340 g/dm3. After rinsing and neutralization in diluted CH3COOH solution, the samples were air-dried at room
temperature, which corresponds to the technological process in real conditions. On the samples, changes in
hydrophilic properties, as well as cotton dyeing properties with anionic dyes were determined: Cuprophenyl Red
3BL140%, Cibacron F-3R, and Cibacron F-3R. On mercerized fabric, the wetting speed increases by 17-40% and
capillary water transport by 20-30% as well, which is very important for the processing and exploitation properties
of cotton. Colors of mercerized samples have a stronger tone 138-155% for light tone and 81-91% for a dark tone,
for samples dyed with direct dye Cuprophenyl Red 3BL140%. Samples dyed by reactive dye also have higher color
intensity than the original fabric. For the light tone, the increase in color intensity has values of 110-269% and the
dark tone 116-170%, for the dye Cibacron yellow F-3R and 91-111% for the lighter tone and 141-180% for the
darker tone for the dye Cibacron F-3R. The increase in wetting and dyeing ability can be explained by
microstructural and morphological changes of cotton fiber and fabric during the mercerization process