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United States Department of Agriculture

Agricultural Research Service

Title: Relationships between micronaire, fineness and maturity. part 1. fundamentals

Author
item Montalvo, Joseph

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2004
Publication Date: September 30, 2005
Citation: Montalvo Jr, J.G. 2005. Relationships between micronaire, fineness and maturity. part 1. fundamentals. Journal of Cotton Science. 9:81-88.

Interpretive Summary: The micronaire of cotton was the first instrumental measure to be included in the classification of this commodity (Heap, 2000). It does not directly evaluate any single physical fiber property, being a combination of fiber fineness and maturity. Micronaire is measured using resistance to airflow. The fineness of cotton is important because yarn made from fine fibers is generally stronger and more uniform than yarn from coarse fibers. Fiber maturity is important since mature fibers, those with well-developed cell walls, absorb more dye and are less prone to cause defects in the finished product. Work is being conducted at the Southern Regional Research Center (SRRC) to develop high-volume instrumentation (HVI) to measure micronaire, fineness and maturity based on the reflectance of different wavelengths of near infrared light. Spinners prefer fibers that are fine and mature rather than coarse and immature. Since only micronaire is measured, growers may be discounted for high or low micronaire cottons that produce desirable yarns. For example, a micronaire of 5 can refer to coarse immature fibers or fine mature fibers; the coarse immature fibers would not produce a desirable yarn. The fundamental measures of biological fineness and maturity are, respectively, cross-sectional perimeter and wall thickness. This research emphasizes the relationships between micronaire, fineness and maturity as functions of simulated wall thickness and perimeter values. The work goes on to show how wall thickness and perimeter together affect fineness, maturity and ultimately micronaire. The overall objective of the study is finding new ways to link micronaire, fineness and maturity. There are several important thrusts: 1) develop appropriate models for fineness, maturity and micronaire in terms of wall thickness and perimeter, 2) generate computer simulated data, 3) study the relative sensitivity of the models to a change in thickness and perimeter, and 4) study the variability in coefficients of determination (R2) between simulated micronaire and either maturity or fineness data. The models are needed because a literature review confirms this is the first report of the relationships between micronaire, fineness and maturity using wall thickness and perimeter as the independent variables. Data is simulated over the full experimental range of thickness and perimeter values and plotted to aid in interpretation of results. Sensitivity of a model to a change in thickness and perimeter is computed at the limits of the simulated variables. Micronaire has been used as a substitute for assessing maturity when the latter measure is not available. Variability in coefficients of determination between simulated micronaire and maturity data is observed. Organizations that need to assess cotton quality can benefit from this research

Technical Abstract: To study the theoretical relationships between cotton (Gossypium hirsutum L.) micronaire, fineness and maturity, models were developed in terms of the cross-sectional dimensions of wall thickness and perimeter. The models were computer simulated over the full range of thickness and perimeter values, the simulated data plotted, the relative sensitivity to changes in thickness and perimeter calculated, and R2 between the models observed. Plots at constant perimeter of micronaire, fineness and maturity against thickness, and plots of micronaire versus fineness or maturity all produce families of lines. These families of lines confound the R2 between the fiber characteristics. The micronaire model is significantly more sensitive to a change in thickness (in m) compared to the same change in perimeter, especially at small thickness values where micronaire is almost independent of perimeter. As thickness increases, the sensitivity to perimeter becomes larger and the result is "high micronaire cotton." For high micronaire fibers, the simulated data provide insight into its computed value

Last Modified: 10/22/2014
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