Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/4/2005
Publication Date: 1/7/2005
Citation: Byler, R.K. 2005. Preliminary data on fiber properties of newly harvested versus weathered cotton. National Cotton Council Beltwide Cotton Conference. CD ROM pp. 795-807. Interpretive Summary: The moisture content of cotton fiber is known to affect the measurement of several commercially important fiber properties such as the fiber strength and fiber length. The fiber moisture content is affected by the temperature and relative humidity to which it is exposed. But, the history of the temperature and relative humidities to which the fiber has been exposed is also known to affect the fiber moisture content. In the past, some of the unwanted variations in the measurement of fiber properties have been blamed on the history of exposure of the fiber to different temperature and relative humidity, which is in most cases unknown. In this study the exposure of some cotton fibers was carefully controlled while otherwise similar fiber was allowed to weather naturally. All of the fiber was then exposed to controlled relative humidity and temperature variations. Statistically significant moisture content differences were seen but the difference was only ±0.14 percentage points. This difference is so small that it would have only a small if any effect on the measurements. Thus, the moisture history of cotton fiber prior to official testing does not have to be considered. Worldwide testing of cotton fiber can be pursued by the cotton industry as a further step toward globalization of cotton utilization.
Technical Abstract: This study was conducted to establish the impact of humidity cycling in the field and laboratory on the moisture content (mc) and physical properties of cotton fiber. Fiber mc has been shown to differ due to environmental conditions such as relative humidity and temperature. White blossoms on cotton plants were tagged in the field and the tagged mature bolls were later hand harvested when the bolls were in one of three conditions--cracked, open, or weathered. All of the bolls were stored in a controlled environment after harvest until the cracked bolls opened. The locules were removed from the carpels and the fiber was then removed from the cottonseed with a small roller gin. The ginned fiber was then exposed to controlled conditions of 70° F and 55% relative humidity (RH) at least another 7 days before the mc was determined by the oven method and Advanced Fiber Information System (AFIS) properties measured. The mc of the fiber did not vary between the cracked and open bolls (5.6%) but the mc from the weathered bolls was significantly lower (5.4%). So, the freshly harvested fiber had a higher mc than the weathered fiber that had been cycled climatically in the field. After exposing the fiber to higher and lower humidity (76° F and 80% RH, and 70° F and 55% RH) repeatedly, the difference in mc between freshly harvested cotton and weathered cotton was reduced (5.7% versus 5.6%) but not eliminated. The relative date of blossom (anthesis) did not affect the mc data but did affect the AFIS fiber length properties. In addition to the blossom tagging order within the row, the humidity cycling significantly affected the AFIS fiber length measurements while the fiber mc had a much lower importance. Additional study is needed to better understand the importance and impact of the relationship between fiber length distribution and humidity cycling.