The Influence of Weathering Prior to Harvest on Certain Properties of Cotton Fibers

Abstract

Most of the.commercial cotton fiber produced in the United States is subjected to a period of from one to many weeks of exposure to the weather before it is harvested from the plant. Such weathering has been shown in prior work to be a cause of changes in the wax on the fiber [19], in the fiber's swelling behavior in alkali [22]. and, under humid conditions, in the pH of water extracts of the fiber [21]. Subsequent investigation now has revealed that a number of other fiber properties also may undergo change during preharvest weathering. These properties include moisture regain at constant relative humidity, dye absorption, content of water-soluble reducing substances, browning tendency, rate of wetting in a water-alcohol mixture, length, strength, and susceptibility to enzymatic decomposition. As might have been expected, the X-ray angle, as defined by Berkley and co-workers [4], showed little if any alteration. Several of the fiber properties which change during weathering have been measured on commercial fiber samples and the results found to show a relationship to the grade of the fiber. Further work is in progress to analyze the nature of the above fiber property changes and to detect other changes which may occur. A rapid and practical test for measuring the water-soluble copper-reducing constituents in raw cotton fiber is described.