Joseph H. Dusenbury

Differential Thermal Analysis of Protein Fibers: Textile Research Institute Princeton, New Jersey, May 31, 1960

1. Alexander, E., Lewin, M., Musham, H. V., and Shiloh, M., TEXTILE RESEARCH JOURNAL 26, 606617 (1956). 2. Gupta. V. D., J. Polymer Sci. 26, 110-112 (1957). 3. Lewin. M., Shiloh, M., and Banbaji, J., TEXTILE RESEARCH JOURNAL 29, 373-385 (1959). 4. MacMillan, W. C., Sen Gupta, A. B., and Mazumdar, S. K., J. Textile Inst. 45, T703-T715 (1954). 5. Rebenfeld, L. and Virgin, W. P., TEXTILE RESEARCH JOURNAL 27, 286-298 (1957). 6. Roy, M. M., J. Textile Inst. 44, T44-T52 (1953). 7. Sen, R. K. and Chowdhury, S. K., TEXTILE RE-

The Influence of Chemical Treatment on the Properties of Wool: I. Alkali Solubility as a Measure of Sulfuric Acid Degradation

The view that the cortex of the wool fiber consists of a resistant fraction, the paracortex, and a less resistant fraction, the orthocortex, which extend in the form of two twisted hemi cylinders from one end of the fiber to the other, is used to explain the mechanism of the alkali- solubility test on acid-damaged wool. The effects of acid damage on several single-fiber prop erties and on the resistance of fabrics to flex abrasion have been measured for correlation with alkali-solubility data. During the initial exposure of the wool to acid damage, alkali solubility is observed to in crease rapidly, corresponding to damage chiefly to the orthocortex; during the later stages, as the damage proceeds into the paracortex, the alkali solubility increases at a much slower rate with time of exposure. The decreases observed in the values for physical properties of the wool with increasing exposure to acid correspond generally with the changes in alkali solubility. Wool treated with formaldehyde, either preceding or following a series of progressive expo sures to acid, exhibits greatly decreased alkali solubility, but fails to show a corresponding im provement in physical properties. It is suggested that the acid acts to degrade the wool fiber by hydrolyzing peptide bonds, and that the formaldehyde treatments decrease alkali solubility by a cross-linking mechanism that does little to improve the physical properties of the wool. A good correlation was found between the flex-abrasion resistance of the variously treated fabrics and the energy to break of the corresponding single fibers. The product of breaking stress and breaking extension, a fiber property related to energy to break, was also found to correlate well with the fabric flex-abrasion resistance.

The Reaction of Formaldehyde with Cellulosic Fibers Part I: Rate and Mechanism of the Reaction1

The acid-catalyzed reaction of formaldehyde with cellulose has been studied under conditions comparable to those of formaldehyde treatments carried out in textile finish ing plants. Cotton, Fortisan, and viscose rayon fabrics were treated at different pad- bath pH values (2.0, 2.2, and 2.4) and formaldehyde concentrations, at different tempera tures (110°, 120°, and 130° C.), and for different periods of time. At the higher pH values of 2.2 and 2.4, the cross-linking reaction seems to take place primarily in the amorphous regions of the fibers; at the lowest pH, a very rapid reaction occurs in the amorphous regions, accompanied and followed by diffusion of formaldehyde into the crystalline regions which controls the observed reaction rate. Both the rate and extent of reaction appear to depend on the state of internal order of the cellulosic material, being least for cotton, the material of highest crystallinity. Fortisan and viscose rayon have about the same degree of crystallinity, but the reaction with Fortisan is more rapid which causes the extent of reaction at later times to be greater than that observed for viscose rayon. Two possible explanations are either that the higher orientation of Forti san facilitates the cross-linking process or that recrystallization occurs during acid hy drolysis, and viscose rayon has a relatively higher rate of recrystallization. The results of X-ray diffraction studies carried out on the variously treated cellulosic fibers are con sistent with the proposed reaction mechanisms.

Differential Dyeing as an Indicator of Bilateral Structure in Wool: New Findings:

Short communications in the form of Letters to the Editor are intended to provide prompt publication of significant new research results and to permit an exchange of views on papers previously published in the JOURNAL. These communications are not submitted to formal review as are research papers, and the editors do not assume any share of the author’s responsibility for the information given or the opinions expressed. When work previously published in the JOURNAL is the subject of critical comment, the authors of the original paper are given

Effects of Crimp and Cross-Sectional Area on the Mechanical Properties of Wool Fibers

Force-extension data for a large number of wool fibers of various types have been analyzed in detail by statistical methods in order to determine the effects of fiber crimp and cross-sectional area on mechanical behavior. During the initial stages of crimp removal, the extensional behavior is controlled by fiber bending; during later stages of crimp removal, this behavior is controlled by both fiber bending and extension. Finally, as the crimp removal approaches completion, the behavior is controlled by the exten sional modulus of the fiber. This modulus is perturbed by differential bending strains associated with crimp removal which act to decrease the modulus below that for an un crimped fiber. Generally good correlation has been found between visual estimates of crimp and mechanical estimates based on analysis of the low-extension region of the fotce-extension curve. The methods of crimp evaluation used indicate that within a group of fibers taken from the same Rambouillet sheep the crimp level increases with increasing fiber diameter, and among fibers taken from sheep of different breeds the crimp level decreases with increasing fiber diameter. It is also observed that the rupture properties, breaking stress and breaking extension. generally increase with increasing fiber diameter.

Mechanical Properties of Feather and Down Fibers Part I: Measurements at 65% RH and 70° F

The elastic moduli of European goose feather barbs and down filaments have been measured at 70° F. and at 65% RH and various pressures of dry air. These latter meas urements at various dry-air pressures have been made to estimate the effects of air- damping on vibroscopic determinations of several fiber properties, have indicated the air-damping effects to be significant but relatively small, and are described in detail in Part II of these papers [6]. A detailed series of measurements has been made at 65% RH and 70° F. of the extensional properties, the bending modulus, and the torsional modulus. The breaking extension is about the same for all the different materials studied, but for the other extensional properties—such as elastic modulus—the properties of the feather barbs are greater than those of the down filaments, and generally the properties of the vane barbs (straight) are greater than those of the fluff barbs (curly). A similar finding holds for the corresponding cross-sectional areas. As in the case of the exten sional properties, the bending and torsional moduli of the feather barbs are greater than those of the down filaments, and vane feather barbs exhibit larger moduli than do fluff barbs. The significance and limitations of these measurements are discussed.

Book Reviews : The Structural Chemistry of Proteins. H. D. Springall, New York, Academic Press, Inc., 1954. x + 376 pages. Price

Preface, Professor Springall explains that this volume has evolved from a course of lectures given to senior undergraduate and graduate students at the University of Manchester. If the quality of those lectures is reflected in this work, the students involved at Manchester were uncommonly fortunate. The first two chapters (Introduction, Peptide Syntheses) deal with the chemical evidence for the polypeptide structure of proteins and discuss the organicchemical procedures used to form polymers of aamino carboxylic acids. The next chapter discusses fibrous proteins and makes use of the two-group classification system of Astbury: the k.yvt. f .-group (keratin-myosin-fibrinogen) and the collagen group. The important contributions of X-ray diffraction, infrared spectroscopy, and electron microscopy to solving the fibrous protein problem are described and correlated. The evidence for the zig-zag form of the polypeptide chains in the stretched )3-state of k.m.f.-group fibers is critically discussed, and there is a masterful summary of the work, principally of Pauling and Corey, that indicated a helical configuration as the best model for the form of the polypeptide chains in the unstretched a-state of the k.m.f.-group proteins and collagen. The author points out in a footnote that it is unfortunate this chapter went to press too early to include the 1952 Royal Society discussions on protein structure. This reviewer feels, however, that such an omission is of minor importance in this case. The fourth chapter (Globular Proteins) discusses the characteristics of soluble proteins and the methods used to measure their sizes, shapes, and molecular weights. Here measurements of osmotic pressure, diffusion and sedimentation constants, viscosity, and light-scattering characteristics are considered, and the reader is cautioned to take some of the conclusions based on