Investigation into a practical approach and application of cotton fiber elongation

Authors: Delhom, Christopher - Chris; Wanjura, John; Pelletier, Mathew; Holt, Gregory; HEQUET, ERIC - Texas Tech University

Submitted to: Journal of Cotton Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2023
Publication Date: 1/26/2023
Citation: Delhom, C.D., Wanjura, J.D., Pelletier, M.G., Holt, G.A., Hequet, E.F. 2023. Investigation into a practical approach and application of cotton fiber elongation. Journal of Cotton Research. 6. Article 2. https://doi.org/10.1186/s42397-023-00139-w.
DOI: https://doi.org/10.1186/s42397-023-00139-w

Interpretive Summary: The quality of cotton fiber is essential to the textile industry because it determines processing performance and product quality. Recent developments have enabled the calibration of elongation measurements performed by the most common cotton fiber testing device, the High Volume Instrument (HVI). These developments allow elongation to be added to the list of fiber traits used in both germplasm development and the selection of cotton bales for processing. However, adding a parameter to the already complex bale selection process increases the complexity of breeding new lines and determining the makeup of a bale laydown. A combined measure of tenacity and elongation representing the intrinsic material property, secant modulus, offers the potential to consider both tenacity and elongation without increasing the complexity of bale selection. A set of twenty-eight samples from the National Cotton Variety Test (NCVT) and two elongation calibration materials, were subjected to single fiber and bundle fiber testing to compare tensile testing methods and determine the utility of secant modulus to breaking elongation and work-to-break. Length distribution characteristics were assessed before and after simulated processing via two stages of mechanical processing with the Shirley Analyzer. Fiber tenacity and secant modulus were significantly correlated with the mean length changes during processing, unlike elongation or work-to-break. Additionally, skein strength and elongation results from samples of the NCVT were used to demonstrate the utility of secant modulus, which was significantly correlated with skein tenacity and elongation. The results obtained on this set of samples indicate that for predicting processing performance, the secant modulus offers a clearer insight into the performance of cotton samples than either work-to-break or breaking elongation.

Technical Abstract: The strength of cotton fiber has been extensively studied and significantly improved through selective breeding, but fiber elongation has largely been ignored, even though elongation contributes to determining the energy needed to break fibers. Recent developments to calibrate the High Volume Instrument (HVI) for elongation has renewed interest in elongation. However, it is not understood how best to utilize yet another fiber property which has the potential to add to the complexity of fiber selection. To explore a practical approach to applying elongation, cotton samples were tested using single fiber methods, the Stelometer, and the HVI. Comparison of strength, elongation, and combined properties such as modulus were explored. HVI testing was shown to be sensitive enough to characterize elongation differences but unlike single-fiber testing it was unable to capture within-sample variation. Fiber bundle testing, like Stelometer and HVI was shown to reduce bias due to fiber selection. The use of secant modulus, an intrinsic material property, allowed for one value to represent both strength and elongation. Secant modulus was shown to contain more useful information than either elongation or work-to-break. Work-to-break was shown to be more influenced by a specific value of breaking force or elongation rather than the intrinsic behavior of the sample being tested. Exploring the influence of genetics and environment on elongation, and its interaction with other fiber properties, requires additional work. Secant modulus, by combining strength and elongation into one value, shows the potential to incorporate elongation values into fiber characterization without increasing the complexity of current fiber selection processes.