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Effect of Moisture on Cotton Fiber Strength

James L. Knowlton


A two part study was conducted to investigate and quantify the relationship between cotton fiber moisture, measured by Near Infrared Reflectance (NIR), and High Volume Instrument (HVI) strength. Samples were collected from cotton bales representing growth regions and plant varieties across the United States. The first part of the study established a mathematical relationship between moisture level and strength by equilibrating the samples to different moisture levels followed by strength and moisture testing. The second part of the study applied the formulated relationship to a duplicate set of samples tested several times while in the process of conditioning.

Investigations of the relationship between moisture and strength resulted in several findings. The strength change per unit moisture change was found to increase with increasing cotton strength. Equilibrium moisture contents of the study cottons at 65 percent relative humidity were found to range from just under 6.7 percent to just over 7.2 percent (wet-basis moisture content). The moisture change per unit relative humidity change was found to increase with decreasing equilibrium moisture content.

Several findings resulted from the application of the strength correction equation developed in the first part of the study. Applying the strength correction to samples at the conditioned state decreased the reproducibility by about three percentage points. Results also indicated that strength corrected reproducibility increased the farther (within limits) the moisture level was from conditioned equilibrium. When the sample moisture deviated from standard equilibrium conditions by about one-half percent or more, the applied strength correction produced a reproducibility equal to or greater than the reproducibility obtained under ideal conditioning and testing procedures.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1300 - 1305
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998