Thermally induced microstructural changes in cotton fibers: A free-volume study

摘要

I measured positron lifetime in natural polymer-cotton fibers as a function of isochronal annealing temperature in the range 27-290degreesC. The variations in the positron results indicated structural changes occurring in the cotton fibers and determined the glass-transition temperature as 80degreesC. Activation energies were measured separately for the crystalline and amorphous regions, indicating the versatility of the technique. These values were close to the O-H bond dissociation energy, suggesting O-H bond dissociation, the most probable process occurring under thermal treatment. As an extension of the positron results, the molecular weight of the cotton fibers was determined to be 1,200,000 based on free volume, which was within the range suggested for cotton. There seemed to be an indication that crosslinking changed the spiral structure of cotton fibers to the network type. However, this needs to be validated by other measurements. (C) 2002 Wiley Periodicals, Inc. [References: 34]