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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Cotton Structure and Quality Research » Research » Publications at this Location » Publication #291521
Title: Understanding water content data in cottons equilibrated to moisture equilibrium

Author
item Montalvo Jr, Joseph
item von Hoven, Terri
item Byler, Richard
item KNOWLTON, JAMES - Agricultural Marketing Service (AMS, USDA)

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/24/2013
Publication Date: 5/31/2013
Citation: Montalvo Jr, J.G., Von Hoven, T.M., Byler, R.K., Knowlton, J. 2013. Understanding water content data in cottons equilibrated to moisture equilibrium. Proceedings of the 2013 National Cotton Council Beltwide Cotton Conference. p. 1047-1055.

Interpretive Summary: Moisture has a significant effect on strength and other important fiber attributes. However, little is understood about equilibrium moisture content data. Scientists have developed techniques that could lead to a better understanding of this information and could be exploited to help manage fiber quality determinations. In this study, moisture is measured by Karl Fischer Titration; the results are referred to as water content. The main locations of water in raw cotton are the botanical trash, other non-cellulosic chemicals and the cellulosic fiber. Water levels are directly measured in the raw material, mechanically cleaned lint, and scoured and bleached fibers. The contribution of the water in the trash and in the non-cellulosic substances to the total level in raw cotton is estimated from differences in the observed readings. The ranges of water contents were dramatically different for the two sample sets investigated. One was from the same growth area and crop year; the other multi area and year harvested. The water content for the cottons with the same growing conditions showed little dependence on maturity, and smaller ranges as well as consistent values for the directly measured and estimated entities. The other set revealed complex relationships and inconsistent values with maturity. The study indicated that extraneous materials in the sample matrix can limit the range of water content in raw and mechanically cleaned cotton. When cotton samples are from one growth area and a recent crop year, the range of water content is minimized and well understood. The techniques developed will serve as useful probes to unravel the physical processes that make up water equilibrium data in cotton and may provide breakthroughs in dealing with fiber quality measurements.

Technical Abstract: The accurate measurement of moisture in cottons conditioned to moisture equilibrium and understanding the data are prerequisites to the development of applications of the data. In this study, moisture is measured by Karl Fischer Titration, which is highly selective for water in cotton; the results are referred to as water content. The main locations of water in raw cotton are the botanical trash, other non-cellulosic materials and the fiber’s cell wall. To aid in understanding the data in samples conditioned to moisture equilibrium, water is directly measured in the raw material, mechanically cleaned lint, and scoured and bleached fibers. The contribution of the water in the trash and in the non-cellulosic substances to the total level in raw cotton is estimated from differences in the observed readings. The contribution of the water in the main constituent (cellulose) of the fiber’s cell wall to that in raw cotton is taken as the water concentration in the purified fibers. The ranges of water contents were dramatically different for two sample sets investigated. In one set, water content for the cottons with the same growing conditions showed little dependence on micronaire. Additionally, this set showed smaller ranges as well as consistent values for the directly measured and estimated entities. The other set revealed a complex relationship with micronaire and inconsistent values for the water entities. This study indicates that extraneous materials in the sample matrix can limit the range of water content in raw and mechanically cleaned cotton. When cotton samples are from one growth area and a recent crop year, the range of water content is minimized and better understood.