A certain level of hairiness in yarn is generally acknowledged as unavoidable because of the practical limitations of mechanical processing machines. Spinners are therefore interested to know the effect of fiber properties on yarn hairiness when selecting suitable raw materials. The literature on parameters such as fiber fineness and short fibre percent reports contradictory trends, while the influence on hairiness of other param eters such as uniformity ratio and fiber quality index is not considered. In this paper, we have investigated the influence of fiber characteristics on the hairiness of cotton yarns.

Using a rapid yarn hairiness tester, the Shirley yarn hairiness meter, this work has confirmed that for cotton yarns, the statistical distribution of the number of protruding ends of different lengths is exponential. The study indicates that, compared to the other hair length settings available on the hairiness meter, the recommended 3 mm hair length is suitable and advantageous. Further there is a high correlation between the Shirley hairiness meter and two other hairiness indices, the modified Jedryka and the Digital fibrograph, considered in this work.

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For the measurement of yarn hairiness, a simple and quick method has been devised on the Digital Fibrograph. model 230 A.

A method has been suggested to utilize the Digital Fibrograph to derive an optical fineness coefficient, which would correlate very well with gravimetric fiber-fineness measurements. Regression equations have been worked out to predict equivalent values of linear density from measurement of the optical fineness coellicient. A comparative study has also been made of the extent of association of the respective Micronaire values as well as values of the optical fineness co efficient with actual gravimetric fineness measurements.

The Scanning Electron Microscope (SEM) was used to probe into the surface structure of three typical sewing threads after abrasion, and an attempt was made to support the visual evidence with the physical data obtained experimentally. Coarse and medium fine yarns showed more hairy appearance on abrasion. Bruising and smoothening effects were rather marked in coarse thread. Twisting of fibers and development of longitudinal cracks occurred in medium fine yam. In case of fine yam, fiber surface damage was not discernible; however, pulled out fibers clustered into a group. Visual evidence of the SEM supports the established view that the extent of damage due to abrasion depends on the size of the yarn, the twist, and the number of plies.

SynopsisInvestigations have been carried out on the changes in the characteristics such as refractive index, density, single fiber breaking strength, and moisture regain of cotton fibers brought about as a result of oxidation with sodium metaperiodate and potassium dichromateoxalic acid. The study has also been extended to sodium chlorite-treated and sodium borohydride-reduced oxycelluloses obtained from these oxycellulose products. Results indicate that in case of sodium metaperiodate oxidation, birefringence and density first increase, reach a maximum and then decrease sharply as oxidation is continued, while breaking strength decreases in the initial stages, reaches a minimum, and then increases in the later stages. With dichromateoxalic acid oxidation, birefringence increases sharply during the initial stages of oxidation and after reaching a maxima, decreases as oxidation progresses, while there is a rapid increase in the values of density during the initial stages followed by a slow rise as oxidation is continued. In case of dichromahxalic acid oxycelluloses, breaking strength decreases continuously with the progress of oxidation. Results are interpreted in terms of changes in gross morphology and fine structure of cotton as a result of oxidation and subsequent chlorite and borohydride treatments.Changes due to chemical modifications in gross and fine structure of cotton and regenerated cellulosic fibers in relation to physical characteristics have been studied by such different techniques as x-ray diffraction, plane and polarized light microscopy, electron microscopy, infrared spectroscopy, etc. As compared with the considerable information available in the literature regarding the fine structure of cellulosic fibers, useful data in the case of chemically modified cellulose obtained by employing optical techniques are rather limited. Kanamaru' has studied the changes in the refractive indices of cellulose oxidized with sodium hypochlorite and potassium permanganate, whereas Pate12 has carried out optical investigations on oxycelluloses obtained as a result of the action of s3dium metaperiodate-sodium chlorite, dichromate-sulfuric acid, and sodium hypobromite on ramie cellulose. Tensile strength characteristics of oxycelluloses have been studied by Clibbens and Ridge13 Davidson,l and Nevell and Zeronian.6 In the present study, systematic investigation has been undertaken regarding changes in the gross morphology and fine structure of cotton fibers 1437

A Micronaire value is an indirect measure of fineness of cotton fiber. This paper describes an experimental procedure by which a Micronaire value can be estimated from 430 model Fibrograph data.