Enhancing the marketability of U.S. cotton through fiber length distribution improvement

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The High Volume Instrument (HVI) is the most commonly used tool to assess the properties of cotton fibers. Within sample variation in fiber length is an important trait throughout many textile processing steps. The HVI currently reports two length parameters, upper half mean length (UHML) and uniformity index (UI). The UI is the ratio of mean length (ML) to the UHML expressed as a percentage. UHML and ML are extracted from the fibrogram. These parameters are used in the current U.S. cotton classification and global cotton marketing systems. The two values are highly correlated and characterize only the longer fibers in a sample. The fibrogram holds more descriptive information than the two measurements provided by the HVI. However, limited information is available about the stability and repeatability of the fibrogram measurement. This dissertation was designed to investigate the stability of the fibrogram, assess the reproducibility across multiple instruments, and determine if corrective actions are required. Three different raw cotton sample sets were tested for this three-stage experiment. The obtained results demonstrate that for a given HVI, the entire fibrogram is stable over both short-term and long-term; however, differences among HVIs were observed. The proposed correction procedure effectively reduces the differences among the four HVI lines. In addition, it was hypothesized that by using unexploited length information from fibrograms would result in improved yarn predictions compared to using currently reported HVI length data. For a set of 60 commercial-like samples, models with new length information captured by the fibrogram perform better in predicting yarn quality than the current HVI and AFIS outputs.

fiber length distribution, calibration, stability, span length, fibrogram, yarn quality