Lloyd B. DeLuca

The Role of Spiral Structure in Untreated and Treated Cottons

The untwisting of the spiral structure was observed as load was applied to the cotton fiber. Reversals are shown to be a vital structural feature which affects the twisting. A reversing spirality represents an idealized structure for obtaining optimum strength, elongation, and elastic recovery from the straight-chain molecules of cellulose. Friction between growth layers and fibrils in such a structure is suggested as a possible cause for permanent set, low intrinsic strength of highly oriented cotton, and the weak points near their reversals. The spiral structure persists through mercerization even though tension is applied; however, the X-ray angle is reduced appreciably. The high alignment achieved by resin treatment of cotton while under tension causes a reduction in elongation and increase in strength from that of slack treatment. The high alignment in cotton resin-treated with tension persists through washing with a detergent in water. Differences between properties of cotton are reduced but not eliminated by mercerization and resin treatment.

Fiber Structure and Mechanical Properties of Untreated and Modified Cottons

A brief review of investigations relating fiber structure to mechanical properties of cotton is given. The relationship of fibril alignment, as measured by the x-ray technique, to the strength and elongation properties of cottons covering a wide range in physical properties is discussed. Alteration of mechanical properties of cotton brought about by degradation in hydrochloric acid, mercerization, decrystallization in ethylamine, resin treatment, and acetylation are related to changes in the fiber structure. The effects of stresses imposed during some treatments are discussed.

A Method of Automating the West Point Cohesion Tester

tester. (~entry [2] has dl’scribed a semiautomatic method to obtain the average drafting force of the W est Point cohesion tester by means of a fading memory integrator. This letter describes a method by which the area under the force-time curve of the W est E’oint cohesion tester is obtained automatically with a continuous integrator. The instrument used in conjunction with the West Point cohesion tester was an Instron ’ I tensile tester, floor model Tut -8, with a Type-1 basic chart drive and Instron integrator. Figure 1 shows a hlock diagram of

The Effect of Testing Conditions on Fiber Drag: Part I: Dynamic Method

The effect of testing conditions on fiber drag when a dynamic drafting force measurement (West Point Cohesion Tester2) is used was investigated. It was demonstrated that the drag characteristic of a particular cotton can best be evaluated by measuring the drafting tenacity at several roll settings. An exponential type of curve was obtained when the reciprocal of roll setting was plotted against drafting tenacity. Based on the equation for a particular draft, the equation for any draft can be derived by multiplying the constant of the equation by the ratio of the drafts. The drafting-force wavelength increased with increases in fiber length, roll setting, and draft, and it corresponded exactly to the wavelength of the sliver thickness wave as obtained with the Saco-Lowell Sliver Tester.

An Evaluation of Hooked Fibers in Cotton Sliver on a Relative Basis

cury discharge) and these showed mean increments of 2.3%, 4.5%, and 11.5% in resistance to compression after 1. 2, and, 8 hr irradiation, respectively. According to Zah~ and Blankenburg [ 11 ], wools of high feltability should, in the felted form at least, have a lower resistance to compression. It was found that this relationship was also true for the bulk compressibility and felting ability of the wools artificially weathered in the Weather-0-Meter. These wools were felted [I] I

The Intrinsic Strength of Natural Cellulosic Fibers

A method of calculating the singte-fiber tenacity at &dquo;zero&dquo; nominal gauge length has recently been presented by I7eLuca (?]. This method depends on the estitii-itioii of an &dquo;end effect&dquo; correction P front an empirical equation by Sippel [4], together with Bellinson’s [1] concept that the breaking extension is independent of the test length. The values of f’ for ramie, 0.624 cni, and for , flax. 0.454 C111....(’e111 to he extraordinarily high. and an examination of the data 5oum leads to an explanation. An lnstron tester BBas used to determine the breaking toads and breaking extensions. v For single tibers, toad ,

The Removal of Dust and Trash from Cotton Sliver by Segmental Drafting

Segmental drafting makes use of a roll with a discontinuous surface, located in the front, bottom position of a two zone drafting system. Segmental drafting removes more coarse trash and dust (larger than 43 μm) and slightly less fine dust than a continuous drafting roll used in the same position. Segment roll design, sliver production rate, drafting force, and draft ratio all have an effect on dust removal.

Crystallite Orientation and Spiral Structure of Cotton: Considerations for Measuring Crystallinity

we had intended in a third paper to discuss methods of interpreting these diagrams so that a measure of crystallinity could be obtained, this discussion is best presented here, as a comment on their recent paper. The two previous papers have shown that the azimuthal scans of the 002 arcs of native and chemically treated cottons can be generated theoretically. Reasons have also been given [2] to show why the three equatorial arcs of cotton have the same shape as that established for rayon [4] ; it is sufficient to extrapolate the meridional intensity to the equator to perform the analysis. However, like Hermans and Weidinger [4] we do not believe that this would be adequate to separate crystalline diffraction from the amorphous background. We propose to show here a method which will establish the correct meridional intensities for cotton at any 20 angle where there may be contributions from other diffraction peaks and to speculate on what intensity can be used at the equator for the amorphous background. It is possible to calculate the meridional intensity ~Imin~ E = ~° ) for the equatorial, radial arcs or any other 20 angles where the diatropic arc or any spurious scatter [5] makes the measure doubtful. The method is shown in Figure 1. It has been established [2] that the meridional intensity for the 002 arc of cotton is free of aberrations. Therefore, it is sufhcient to measure Q (50% intensity angle) from the 002 arc; find this same angle on the 101 or 101 arc (or at any angle 20) ;