Formulas are derived for the frequency of flexural vibration of a vertical uniformly tapered circular shaft mounted at one end. The Rayleigh and Dunkerley methods are used and the results compared both with known results of exact analysis and with experi-

A serious problem in single-fiber testing is the preparation of a homogeneous sample from which fibers may be selected in a random manner. Mechanical blenders, of the type developed for cotton by the U. S. Department of Agriculture, greatly improve the homogeneity of a bulk fiber sample. In the present work tests were made to show what changes in single-fiber proper ties result from the mechanical action of such a blender. Relatively small changes in mechanical behavior of the cotton fibers were observed as a result of blending. With the conventional three passes through the blender a small decrease in break ing load (less than 10%) was found, with corresponding changes in breaking stress and energy to break. A reduction of fiber crimp with a slight increase in fiber length by the fiber array method was also noted.

Several years ago Hall and Elting pointed out that certain raw cottons which had been subjected to the action of fungi in the field or immediately after harvesting suffered a deteriora tion in cotton quality characteristics upon storage in bale form. Such cotton was termed by them to be cavitomic. This deterioration was most manifest in a reduction of processing efficiency and a lowering of yarn quality. Certain chemical tests (pH and reducible sugars) were established as methods to detect cavitomic cotton. Because there seemed to be consider able lack of information regarding the nature and primary causes of quality deterioration at tributable to cavitomic cotton, the study presented in this paper was undertaken to determine what changes in fiber properties resulting from the cavitoma might be responsible for the effects noted previously.The opportunity for this study was presented when it was found that 3 of 12 bales of a homogeneous lot of Deltapine 15 cotton obtained for another investigation gave...

The structural reversals in cotton fibers are a preferred location of break when the fiber is ruptured in tension. With the aid of a polarizing microscope, observations were made of the fraction of fibers breaking at the reversals under various conditions of moisture content, specimen length, and chemical treatment. It is concluded that the cellulose in the region of the reversals is more highly crystalline than the cellulose between the reversals. The cause for breakage at the reversals is then explained on the basis of internal stresses at these points which cause the fiber to tear apart when tension is applied. The weak places between reversals which give rise to fiber rupture are believed to be at structural defects or thin places. The mean breaking stresses for fibers breaking at the reversals vary significantly from those for fibers breaking between reversals for some varieties of cotton. The distributions of weak-spot location and strength for reversals and structural defects are discussed for three varieties.

The molecular properties of silk fibroin are such as to make the regeneration of silk worthy of serious consideration. Not only is the molecular weight such as to indicate at least 500 units in the polymer, but, also, the component residues are among the simplest amino acids, without bulky side groups. Thus, the interchain attraction is the highest of several representative polymers. The mechanical problems of silk regeneration are not easily overcome, however. Many solvents degrade the fibroin appreciably, and, so far as is known, aqueous solutions of concentration com parable to that found in the silkworm have not been made. The structural simplicity which gives rise to good polymer properties is also conducive to instability of aqueous solutions. While important in an over-all appraisal of silk regeneration, the economic problems are not discussed in this paper.

An apparatus for stretching and relaxing single fibers for the purpose of determining mechanical hysteresis losses is described. Results obtained on cotton, viscose rayon, and nylon fibers are compared with similar data previously obtained on cords from which the fibers were taken. Such comparison indicates that interfiber friction is probably the major cause of hysteresis energy losses in cotton and rayon tire cords under cyclic loads at low frequencies.

The punched-card method is illustrated, with a description of the procedures used in analyzing the data on single cotton fibers. The samples were tested for 7 properties, from which 5 more were derived by computation. For each of these 12 properties there were prepared a histogram showing the distribution of the property values within variety groups, means and standard devi ations for 6 subgroups within each variety, and a three-factor analysis of variance of the means for all varieties and subgroups. The steps in obtaining these results from the punched cards are outlined. Some advantages of this method over the desk-calculator approach are discussed.

A modified method for evaluating the distribution of pore spaces within a textile fabric, based on the principle outlined in the preceding paper in this series [1], is described. Data are reported for 14 tight fabrics, 6 of which had been treated with a water-repellent finish. The porosities of these fabrics are compared with the results of air- and hydrostatic-permeability measurements.

Research on the apparent densities of cellulose fibers in different liquids gives information concerning inner fiber structure which may be useful in characterizing certain desirable prop erties of cotton fibers. The following report describes an investigation of some factors involved in evaluating density data in terms of fiber structure. The interpretation is made of some experimentally determined densities of cotton and rayon fibers in benzene and in dioctyl phthalate —two liquids differing greatly in molecular dimensions—and in mercury, a nonwetting liquid. In the last case, the "over-all density" of a fiber, defined as the average density of all material within the outer wall of the fiber, is determined by a method utilizing a mercury-pressure volumenometer.In the case of the wetting liquids, higher densities were obtained with benzene—which has the smaller molecule; this indicates that the fibers have pore spaces which in size approach the dimensions of the molecule. When the cotton fibers are cut into short sections, about 1 mm. long, more of these pores and intrafiber channels are open to the liquid medium; a higher density is, therefore, obtained for the cut fibers than for the whole fibers. Pore-space values within the fiber are calculated and compared with values obtained by other methods. The significance of these observations in the consideration of fiber structure is discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHysteresis, Elastic Modulus, and Growth of Tire Cords under Comparable LoadsEdith Honold and Helmut WakehamCite this: Ind. Eng. Chem. 1948, 40, 1, 131–134Publication Date (Print):January 1, 1948Publication History Published online1 May 2002Published inissue 1 January 1948https://pubs.acs.org/doi/10.1021/ie50457a035https://doi.org/10.1021/ie50457a035research-articleACS PublicationsRequest reuse permissionsArticle Views334Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Calorimetric Investigation of Moisture in Textile Fibers1aFrank C. Magne, H. J. Portas, and Helmut WakehamCite this: J. Am. Chem. Soc. 1947, 69, 8, 1896–1902Publication Date (Print):August 1, 1947Publication History Published online1 May 2002Published inissue 1 August 1947https://doi.org/10.1021/ja01200a015RIGHTS & PERMISSIONSArticle Views155Altmetric-Citations64LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (754 KB) Get e-Alerts Get e-Alerts