Chemical Properties of Field-Weathered Cotton

Abstract

fectiveness and optimum concentration of finishes used to improve sewability and on their effect on internal needle temperatures. RecommendationsThe data presented in this report suggest that some specific changes in needle design should reduce needle temperatures. The following examples are given :a. The holes should be punched in the needle shank above the eye to increase surface area-to-mass ratio and decrease heat stored by the needle. This would also make cooling during sewing more efficient and make cooling by compressed air more effective.b. The needle shank should be grooved to increase the area exposed to normal air cooling due to machine operation or compressed air cooling and to increase heat dissipation due to radiation. c. Provision should be made for partial internal cooling through the needle butt by compressed air or gas, since needle internal temperatures are higher than surface temperatures during and just after the sewing operation. This paper deals with the chemical changes in cotton fiber through field weathering. The chemical changes which occur are important for several reasons.Structural changes in the cellulose molecule which have an effect on dyeing occur. Cellulose chain length is decreased [3] and ultimately the utility of the cotton suffers. Previous work [6] on the physical properties of weathered cotton gave indications of length shrinkage which may be interpreted as possible structural changes in the cellulose molecule (crystallinity) .Marsh and coworkers [9] have published extensively on cotton-weathering research. In the publication cited, they have also reviewed the literature.Work undertaken here attempts to evaluate weathered cotton through chemical tests. The early cotton was field weathered up to 5 mo, whereas the later cotton was in the field for more than 2 mo. Since cotton varies in composition from early to late opening, an additional weathering variability has been added to cotton-weathering research. ExperimentalThe field plans of the experiment were given in a previous publication [6] and will not be repeated here.Degree of polymerization determinations were made by forming cellulose nitrate and dissolving the nitrate in butyl acetate. The intrinsic viscosity was calculated from the equation of Baker as modified by Philippoff [11] ] in which [~] = 8/c (1]r1/8-1). A correction in intrinsic viscosity was made for incomplete nitration by the method suggested by Lindsley [8]. Degree of polymerization was derived from the Staudinger expression DP = K [q] where K = 118 for cellulose nitrate in butyl acetate. The value of K was chosen after the review of the literature. This constant affected the magnitude of the DP value but plays only a small part in weathered difference in DP calculations.Copper reduction values and aqueous-extract pH were run according to the methods outlined by Marsh [9]. Carboxyl groups were determined by the method of Pacsu [7], in which an excess of dilute NaOH is 1 Fiber and Spinning Laboratory of the Cotton Research Committee of Texas.

Delayed harvest time affects strength and color parameters in cotton fibers

“…In contrast to our study, Kelly (2006) observed significant reductions in UHML over the 3 years of the study due to weathering. The decrease in UHML could be explained by cellulose chain damage and oxidation as reported by Hessler and Upton (1955). In this regard, the absence of significant differences in UHML presented here could be attributed to a shorter exposure time or more favorable environmental conditions compared to those of the works mentioned before.…”

Heat Induced Chemical Changes in Cotton Fiber

“…Since the late cotton will be less developed and show lower cellulose content, a loss of extraneous material other than cellulose may be expected. Thus, the reaction to adsorption may be altered by field weathering [ 1 ].…”

The Relationship Between Cotton Fiber Development and Fiber Properties

“…'I~lu· Arealometer was used to obtain lx rimeter (diameter and area), iiiaturity, immaturity ratio/ shape factor, and wall thickness I 11. Methods for determining chemical properties, cellulose; amorphous cellulose, dye absorption, and moisture regain have been described in other publications ( 3,4 (Table I ) . Although length is included among the physical properties, because of its association with strength and fineness in the characterization of cotton, length 1 Immaturity ratio, defined as the ratio of the area of a circle having the same perimeter' as an average fiber to the actual cross-sectional area of the fiber also measures filx-r size and must 1)(' considers!…”