The Function of Swelling in the Finishing of Cotton 1

The mechanism of the interfibrillar and intrafibrillar swelling of cotton has been investigated by infrared and x-ray methods. Emphasis is on swelling in caustic soda, but other reagents are also considered. The presence of intrafibrillar swelling can be shown by detection of intermediate complex formation, while the swelling agents are present. The swelling behavior and the structural changes produced in the cotton are modified by the effects of tension and also by the presence of additives in the swelling solution. Whether the swelling complexes are intermediate in the conversion of cellulose I to cellulose II, or a reconversion to cellulose I results on washing out the swelling agent and drying, depends on the degree of swelling at different stages of the process. Intrafibrillar swelling is usually accompanied by an increase in the hydrogen-bond disorder, even if reconversion to cellulose I takes place, and the detection of this increase in disorder by ir-deuteration methods may be the only indication of an intrafibrillar swelling process. An explanation of the observed behavior is put forward in terms of the concept of cellulose sheets.

The ideas developed from a study of the swelling of cotton by caustic soda and other swelling agents have been used in explaining the effects found in the mercerization and other finishing processes applied to cotton.