Devron Thibodeaux

Cotton Fiber Chemistry and Technology

Cotton fiber chemistry and technology , Cotton fiber chemistry and technology , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Cotton Fiber Maturity by Image Analysis

Applications of state-of-the-art image analysis techniques to measuring cotton (Gos sypium sp.) fiber maturity are reported. Individual cotton fibers arrayed longitudinally on microscope slides are optically scanned by the image analyzer. The fibers video image is automatically broken into narrow bands for discreet measurements of pro jected fiber widths along its length. The ratio of the average maximum to the average minimum of these measurements is related to the degree of development of the sec ondary wall of each fiber. Results are reported for several cotton varieties of either measured maturities or of known fiber post-anthesis ages.

Creation of a Set of Reference Material for Cotton Fiber Maturity Measurements

It was the goal of the authors to create a set of reference cottons for maturity measurements. To achieve this they selected 104 cotton bales representing the two principal cultivated species. The vast majority of the bales originated in the USA, but some foreign-grown cotton bales were also selected (Egypt, Uzbekistan, Pakistan, Cameroon, Syria, Benin, and Australia). A representative sample of approximately 30 kg (70 pounds) was taken from each bale. Each sample was homogenized according to the protocol used by the International Cotton Calibration Standard Committee (ICCSC) to produce reference cottons. Eight sub-samples per bale were taken and a minimum of 500 cross-sections per sub-sample were analyzed. A broad range of average values of fiber perimeter and fiber maturity for the 104 bales were obtained. Evaluation of the mathematical and statistical relationships pertinent to maturity and fineness revealed that four critical criteria for adequate calibration standards were met. Therefore, this population of bales constitutes a good base for the calibration of the indirect measurement instruments for maturity and fineness.

Applying Microscopy to the Development of a Reference Method for Cotton Fiber Maturity

Two microscopic methods for characterizing the maturity of a cotton sample have been developed, using either cross-sectional or longitudinal scanning of fibers by image analysis. This study compares the two methods for consistency with the aim of opti mizing their efficiency and accuracy as reference methods. Longitudinal scans of cotton fibers at immature (3.5 weeks post-anthesis) and mature (7 weeks, field opened) growth stages are compared with cross-sectional measurements of the same fiber samples. Maximum projections along the length of cotton fibers agree with cross-sectional mea surements, but minimum projections do not. Variations in fiber twisting and folding render minimum width projections inaccurate. The only true measure of wall thickness is from cross-sectional data, and fiber alignment is critical. Sample preparation for developing a reference method dictates that bundles of combed, parallel fibers be sectioned in the center. This procedure will decrease errors in sampling due to the natural taper of the fiber along its length.

Development of Fourier transform infrared spectroscopy in direct, non-destructive, and rapid determination of cotton fiber maturity

Fourier transform infrared (FTIR) spectra of seed and lint cottons were collected to explore the potential for the discrimination of immature cottons from mature ones and also for the determination of actual cotton maturity. Spectral features of immature and mature cottons revealed large differences in the 900—1200 cm1 region, and such spectral distinctions formed the basis on which to develop a simple three-band ratio algorithm for classification analysis. Next, an additional formula was created to assess the degree of cotton fiber maturity by converting the three-band ratios into an appropriate FTIR maturity (MIR) index. Furthermore, the MIR index was compared with parameters derived from traditional image analysis (IA) and advanced fiber information system (AFIS) measurements. Results indicated strong correlations (R2 > 0.89) between MIR and M AFIS and between MIR and MIA among either International Cotton Calibration standards or selected cotton maturity references. On the other hand, low correlations between the pairs were observed among regular cotton fibers, which likely resulted from the heterogeneous distribution of structural, physical, and chemical characteristics in cotton fibers and subsequent different sampling specimens for individual and independent measurement.

Anatomy of a Nep

Neps appearing in all stages of textile processing up to the dyed fabric were extracted from cotton samples. These neps were disassembled and the individual fibers making up each nep, along with any foreign material appearing in the nep, were studied using microscopic techniques. Three distinct types of neps could be recognized. The data obtained from each tend to support the theory that for the most part, problematic neps are a result of immature fibers present in the cotton.

Rapid measurement of cotton fiber maturity and fineness by image analysis microscopy using the Cottonscope

Two of the important cotton fiber quality and processing parameters are fiber maturity and fineness. Fiber maturity is the degree of development of the fiber’s secondary wall, and fiber fineness is a measure of the fiber’s linear density and can be expressed as mass per unit length. A well-known method for fiber maturity and fineness is a cross-section image analysis and microscopy measurement. In general, typical cross-section image analysis and microscopy methods for fiber maturity and fineness can be slow and tedious to perform. Much interest has been shown in improved and rapid routine measurements of fiber maturity and fineness in the laboratory. The Cottonscope® is a new small footprint instrument for measuring fiber maturity and fineness, consisting of a longitudinal measurement of weighted fiber snippets in water using polarized light microscopy and image analysis. A program was implemented to assess the potential and capabilities of the Cottonscope to measure cotton lint maturity and fineness and to determine the major operational impacts on the Cottonscope results. The measurement was fast and easy to perform. The major operational impact on the Cottonscope results was environmental conditions (room temperature and relative humidity), and its impact was a concern for fineness only. Very good method agreement was observed between the Cottonscope and image analysis and microscopy method for maturity and fineness, with moderate coefficients of determination, R2s, and low residuals. Recommended operational protocols for routine Cottonscope measurements were developed.

Characterization of Attenuated Total Reflection Infrared Spectral Intensity Variations of Immature and Mature Cotton Fibers by Two-Dimensional Correlation Analysis

Two-dimensional (2D) correlation analysis was applied to characterize the attenuated total reflection (ATR) spectral intensity fluctuations of immature and mature cotton fibers. Prior to 2D analysis, the spectra were leveled to zero at the peak intensity of 1800 cm−1 and then were normalized at the peak intensity of 660 cm−1 to subjectively correct the variations resulting from ATR sampling. Next, normalized spectra were subjected to principal component analysis (PCA), and two clusters of immature and mature fibers were confirmed on the basis of the first principal component (PC1) negative and positive scores, respectively. The normalized spectra clearly demonstrated the intensity increase or decrease of the bands ascribed to different C–O confirmations of primary alcohols in the 1050–950 cm−1 region, which was not apparent from raw ATR spectra. The PC1 increasing-induced 2D correlation analysis revealed remarkable differences between the immature and mature fibers. Of interest were that: (1) Both intensity increase of two bands at 968 and 956 cm−1 and the shifting of 968 cm−1 in immature fibers to 956 cm−1 in mature fibers, together with the intensity decreasing and shifting of the 1048 and 1042 cm−1 bands, are the characteristics of cotton fiber development and maturation. (2) Intensities of most bands in the 1800–1200 cm−1 region decreased with the fiber growth, suggesting they are from either noncellulosic components or CH and OH fractions in amorphous celluloses. (3) The reverse sequence of intensity variations of the bands in the 1100–1000 cm−1 and 1000–900 cm−1 region of asynchronous spectra indicated a different mechanism of compositional and structural changes in developing cotton fibers at different growth stages.

A New Single Fiber Tensile Tester1

A new instrument for single fiber tensile testing is evaluated and data from two cotton species are presented. The instrument allows rapid accumulation of data that, before inception, were extremely tedious and labor intensive to obtain. Results include tensile strength and percent elongation at different gauge lengths and rates of extension, and an optical measure of fiber diameter or ribbon width as well as an indication of the extent of convolutions.

Two-Dimensional Attenuated Total Reflection Infrared Correlation Spectroscopy Study of the Desorption Process of Water-Soaked Cotton Fibers

Two-dimensional (2D) correlation analysis was applied to characterize the attenuated total reflection (ATR) spectral intensity fluctuations of native cotton fibers with various water contents. Prior to 2D analysis, the spectra were leveled to zero at the peak intensity of 1800 cm−1 and then were normalized at the peak intensity of 660 cm−1 to subjectively correct the changes resulting from water diffusion in fibers and resultant density dilution. Next, a new spectral set was subjected to principal component analysis (PCA) and two clusters of hydrated (≥13.3%) and dehydrated (<13.3%) fibers were obtained. Synchronous and asynchronous 2D correlation spectra from individual ATR spectral sets enhanced spectral resolution and provided insights about water-content-dependent intensity variations not readily accessible from one-dimensional ATR spectra. The 2D results revealed remarkable differences corresponding to water loss between the hydrated and dehydrated fibers. Of interest were that: (1) the intensity of the 1640 cm−1 water band remains in a steady state for hydrated fibers but decreases for dehydrated fibers; (2) during the desorption process of adsorbed water, small and water-soluble carbonyl species (i.e., esters, acids, carboxylates, and proteins) begin to accumulate on the cotton surface, resulting in possible changes in the coloration and surface chemistry of native cotton fibers that were rained on prior to harvesting; (3) intensities of bands in the 1200 to 950 cm−1 region exhibit a more apparent intensity increase than those in the 1500 to 1200 cm−1 region, indicating the sensitivity of the 1200 to 950 cm−1 infrared (IR) region to intra- and inter-molecular hydrogen bonding in fiber celluloses; and (4) the 750 cm−1 band, ascribed to the unstable Iα phase in amorphous regions, might originate from the cellulose–water complex through hydrogen bonding.