Determination of cotton fiber maturity and linear density (fineness) by examination of fiber cross-sections. Part 1: Comparison of two image analysis systems used in conjunction with optical microscopy

Abstract

Researchers from the United States Department of Agriculture and Texas Tech University have published the establishment of a set of reference cottons with known fiber maturity and linear density (fineness) values. Their work was based on careful analysis of the dimensions of a large number of individual transverse fiber cross-sections viewed under the optical microscope to obtain representative values for a particular cotton. Since this set of reference cottons has a high potential value for instrument developments and the world’s cotton industry in general, it was considered useful to independently test both the processes used and the assigned values for this set of reference cottons. Using independently developed software, a careful cross-section by cross-section comparison with the original data identified that the measured fiber perimeter values were in good agreement. However, cell wall area values and, consequently, the fiber maturity (theta) and fineness values were consistently smaller. The difference ranged from up to 40% for the small cell wall area values down to 15% for the larger cell wall area values, with the average difference being approximately 20%. These differences stem from a different interpretation of the outside boundary of the fiber cross-section by the two image analysis systems due to the limited optical resolution of the captured images. This implies that while the ranking of fineness and maturity values originally assigned to the reference cottons is likely to be correct, there may be a significant systematic error in the assigned values of the cell wall area and hence fiber maturity and linear density values.

Comparing accuracy of the methods of polytetrafluoroethylene fiber linear density measurement

“…Cross-section area calculation. As reported elsewhere, 13,[15][16][17] cross-section area was used to calculate fineness of polymeric and natural fibers. In our work, several bundles of fibers treated by the above combing operations were cut into slices with clear cross-sections and imaged with scanning electron microscopy (SEM).…”

“…More importantly, the airflow and cross-section methods applied to analyze the average linear density of irregular fibers have been reported. [13][14][15][16][17][18][19][20][21][22][23] However, almost no study has focused on measuring linear density of PTFE split-film fibers. The purpose of this study is to compare the accuracy of PTFE split-film fiber linear densities obtained from various test methods (gravimetric measurement, cross-section method, theory calculation, airflow measurement, assumption calculation, and vibration method).…”

Determination of cotton fiber maturity and linear density (fineness) by examination of fiber cross-sections. Part 2: A comparison optical and scanning electron microscopy

“…The average characteristics for these cottons obtained by Hequet (personal communication) are summarized in Table 1. Fiber cross-sections were prepared as described by Higgerson et al, 8 a full implementation of the technique developed by Boylston et al 30,31 Two important features of the process of Boylston et al were (a) a focus on aligning the fiber axis normal to the crosssection plane, to minimize systematic errors due to the cross-sections being cut ''on an angle'', and (b) avoiding fiber swelling during the cross-sectioning process. The aligned fibers, carefully packed inside narrow (1/8 in internal diameter) tubing, were embedded in methyl, butyl, methacrylate (MBM) resin.…”

“…32 A revised software system has been developed to overcome this problem. 33 Recently Higgerson et al undertook a study to validate the processes and data reported by Hequet et al 8 A cross-section by cross-section comparison of the results of analyzing a set of captured images analyzed both with the original software (FIAS) and independently developed software demonstrated good agreement in fiber perimeter values, but approximately 20% difference in cell wall area values. It was identified that these differences arise from the limited optical resolution of the captured images such that the two image analysis systems have a different interpretation of the outside boundary of the fiber cross-section.…”

“…During growth the fiber cross-section is approximately circular in shape with a circular lumen which collapses when the fiber dries resulting in the characteristic irregular kidney shape illustrated schematically in Figure 1. The fiber maturity ratio (one commonly used definition of fiber maturity [3][4][5][6][7][8] ) is calculated from the fiber perimeter P and the cell wall area A C values identified in Figure 1. Firstly the degree of secondary wall thickening theta () is defined as the ratio of the cell wall area (A C ) to that of a circle having the same perimeter as the fiber cross-section, i.e.…”