The effects of tension during resin treatment on the physical properties of yarns and fibers that had received various combinations of pretreatments were investigated for Pima, Bobshaw, and Deltapine cottons. Pretreatments included scouring, mercerization, and acid degradation. Dimethylolethyleneurea (DMEU) resin was applied at 2 and 5% add-on. Relationships between bundle and yarn tensile properties were studied and found to have high correlation. Some evidence was found that degradation prior to tension during resin curing has the effect of preventing strength losses due to crosslinking. Degradation was observed to inhibit relative elongation losses in yarns due to tension curing. Degradation caused lower values of toughness whereas mercerization prevented such losses.

High correlation is shown to exist between crystallite orientation and tensile proper ties of bundles of cotton fibers. Statistical analyses of bundle data failed to uncover pronounced dependence of bundle tensile properties on reversal frequency. Evidence is given of the influence of heredity on reversal frequency. Data on single cotton fibers are presented to illustrate the relationships or lack of relationships of reversals and x-ray angle to strength and elongation. X-ray angle and reversal frequency are interrelated at a very low level of significance and are shown to be related to single-fiber tenacity, elongation, and decrease in strength with increase in gage length. The tensile properties from bundle and single-fiber measurements are more strongly related to x-ray orientation than to reversal frequency.

The influences of growth environment on gross and fine structures, mechanical properties, and responses to chemical treatments were determined from cotton fibers of Rex and Texas Marker-1 varieties grown under ranges of controlled environment. Cell walls of fibers composed of cellulose deposited at constant and varying temperatures were found to differ in many of their properties. The cell wall thickens more slowly at lower than at higher temperatures and the walls are thinner even though the wall development periods are longer. Properties of fibers indicate that cellulose from the low-temperature environment is less compact and more responsive to chemical reagents than from the high temperatures. The fibers from low temperatures are weaker and more extensible. Relationships between cell wall thickness, fine structure, mechanical properties and chemical reactivities are illustrated.