Wilton R. Goynes

Cotton Fiber Chemistry and Technology

Cotton fiber chemistry and technology , Cotton fiber chemistry and technology , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

A Scanning Electron-Microscope Study of Washer-Dryer Abrasion in Cotton Fibers

Untreated and chemically modified cotton fabrics which had been laboratory-abraded by machine-washing and tumlle drying were studied with the scanning electron microscope. Generally, abrasion patterns were not different from those normally associated with any wet or dry abrasion. Greater differences were observed between washing machine-abraded and dryer-abraded samples than between treated and untreated samples abraded by the same method.

A Microscopical Survey of Flame-Resistant Cotton Fabrics Part I: Treatments Based on THPOH-NH 3

Three cotton printcloth fabrics treated for flame resistance with THPOH-NHx, oxidized and nonoxidixed, were studied by light microscopy and by transmission (TEM) and scanning (SEM) electron microscopy. Chars of the treated fabrics were also examined. Staining with Acid Blue I and examination by light microscopy provided a semicluantitative assessment of penetration of nonoxidized THPOH-NHa into yarns and fibers, but was less effective with the oxidized sample. SEM observations indicated polymer build-up on fabric surfaces. Deposits of polymer between fibers were usually heavier around the periphery of the yarn. Laundering removed surface deposits but oxidized samples laundered 50 times were still flame resistant, TEM of ultrathin cross sections showed that no major structural change had occurred in the treated fibers. Both SEM and TEM of fiher char sections indicated that the fibers had become shells on burning. Residue patterns left by treated fiber sections after microincineration suggested that the laulymer had completely penetrated the fibers.

Effects of Heat on Cotton, Polyester, and Wool Fibers in Blended Fabrics - A Scanning Electron Microscopy Study

Treating cotton textile fabrics with phosphorus-containing flame retardant finishes reduces the flammability of the fabrics. The presence of fibers other than cotton in blended fabrics changes the burning rates and char lengths of the fabrics, as well as the nature of the resultant chars. To better understand the relationship of blended fibers during burning, and the response of each fiber to heat, scanning electron microscopy was used to study structures of blended cotton/polyester and cotton/ wool fabrics, and of individual fibers, both before and after exposure to flames. In blended fabrics, changes in physical structures of polyester and wool were observed before those in cotton. Chars of blended fabrics were more stable than those from either fiber alone, because the charred cotton formed a network onto which the melted polyester and wool could flow. These melts in turn protected and strengthened the cotton residue.

Nontraditionally Retted Flax for Dry Cotton Blend Spinning

Extracting flax fibers from the stems of Linum usitatissimum plants has traditionally been a costly, labor-intensive process, largely restricted to Europe and Asia. The naturally long, strong fibers are typically processed on wet spinning machines that are not available in the United States. However, the resurgent popularity of flax has promoted an interest in devising more economical methods of producing and processing the fibers domestically. This preliminary study investigates the use of flax fibers extracted by mechanical, chemical, and enzymatic retting as well as traditional (dew) retting methods. The experimental fibers show promise for spinning on common cotton machinery in blends with cotton. The research has produced a series of medium-count, experimental apparel-grade yarns with an attractive appearance and acceptable hand. With refinement, chemical or enzyme retting can perhaps become an ecologically sound and cost effective method of producing flax fibers.

Microscopical Studies of Cottons Reacted in Vapor Phase

Morphological effects of the modification of cotton by vapor-phase treatments were studied by light and electron microscopy. Observations were made of etherified, grafted, and cross-linked cottons. The uniformity of reaction was followed by swelling whole fibers in cupriethylenediamine hydroxide (Cuene) solution and observing the swelling and dissolution along the length of the fiber. In addition, ultrathin sections were prepared and dissolution characteristics of the sections, after immersion in Cuene, were observed with the electron microscope. Observations of cotton cross-linked with methanol hemiformal in the presence of SO2, in an open constant-volume reactor, gave indications that little reaction had occurred; reacted areas observed were at the periphery of the fiber. Samples of cotton cross-linked with vapors of paraformaldehyde, with formic acid as catalyst, appeared to be cross-linked throughout the fine structure of the fiber; when HCl or SO2 was used as the catalyst in this reaction, peripheral crosslinking was observed. When fabrics were treated for long periods of time with formalin in the presence of SO2, the reaction seemed to penetrate the entire structure of the fiber; after short periods of treatment it was peripheral. Large amounts of HCl with formalin resulted in some limited cross-linking of the fiber. When cotton was treated in a closed, constant-pressure reactor with formalin in the presence of SO2, the cellulose was reacted throughout the fiber. Observations of a series of cottons impregnated with 2-hydroxyethyl carbamate exposed to butanol hemiformal vapor indicated that the degree of penetration of the cross-linking agent was dependent upon the length of time the samples were exposed to the cross-linking agent in the vapor phase. Examination of sections from cotton grafted with acrylic acid revealed that the material remaining after solution in Cuene was not fibrillar, but rather one of spongy character. Hydroxyethylation made the fiber sensitive to a dimethylolethylene urea (DMEU) cross-linking treatment.

Identification of biological dusts by elemental analysis

The feasibility of identifying, by microscopial and X-ray techniques, the biological source of cotton plant dusts produced from individual plant parts was determined. Major elements observed were magnesiu, aluminum, silicon, sulfur, chlorine, potassiu, and calcium. Some plant parts were distinguished by variations in elemental content. The most characteristic elements were postassium and calcium. Relative peak heights of elemental spectra were used to identify the plant part from which the dust was derived.

Microscopical Analysis of Chemically Modified Textile Fibers

Properties of textile fibers are altered to achieve specific qualities by treatment with various chemical finishes. These finishes produce changes that may be observed through direct or indirect microscopical procedures. In developing and evaluating finished fabrics, it is advantageous to determine sites of interaction of the finish and the fiber, since it is generally intended that finish chemicals be located in a particular area of the fabric structure. Microscopical techniques have been developed to show locations of these finishes. Scanning electron microscopy provided a means for showing deposition of finish on fabric and fiber surfaces, and energy dispersive X-ray analysis was used to show the presence of specific elements on or within fibers.

Microscopical Evaluation of Cellulose Esters with Low Degrees of Substitution

The effects on cotton of esterification to low degrees of substitution have been investi gated by light and electron microscopy. Observations were made on partially esterified celluloses which included esters of acetic, palmitic, stearic, 12-hydroxystearic, linoleic, and ricinoleic acids and of the aromatic benzoic, cinnamic, naphthoic, and pkenylundecanoic acids. The uniformity of the esterification of cellulose was followed by dyeing and swelling techniques. Refractive index measurements were used to follow changes in optical anisotropy which accompanied the chemical modification. The average refractive indices of cellulose esters containing aromatic groups were greater than those of the esters with aliphatic substituents, the greatest difference being between indices measured perpendicu lar to the fiber axis. The normal fibrillate texture of the scoured surface appeared to become smooth upon esterification. Fragmentation of the esters in water in a laboratory blendor produced long strands of fibrillate material intermingled with clumps of spongy or amorphous material. On de-esterification of the fragments with an alcoholic base, the structure of the material reverted to that of unesterified cotton—fibrils became distinct and, in some cases, saponification proceeded to a stage where hydrocellulose-like particles were formed. , Many of the esterified fibers of low degrees of substitution swelled in the conventional methacrylate embedding technique. The swelling caused the cell wall to separate into layers, and the internal structure could then be studied by examination of thin sections of these fibers with the electron microscope. By use of an alternative embedding medium, aqueous polyvinyl alcohol, in the preparation of thin sections, compact unlayered struc tures of the esterified cottons were obtained. This permitted observations of the undis turbed structure of the modified cottons. Both types of observations were used in the microscopical evaluation of cotton fibers esterified to low degree of substitution to demonstrate structural changes brought about by the esterification reaction.

Biodeterioration of Nonwoven Fabrics

The use of nonwoven fabrics in disposable, convenience products generates high quantities of wastes that are not biodegradable. Synthetic fibers provide a major source of materials for these disposable products. Because synthetics are generally less bio degradable than natural fibers, it appears that for maximum degradability, natural fibers are a likely choice of materials for disposable goods. To compare rates of bio deterioration for natural and synthetic fibers, we examined changes in the structure and strength of nonwoven fabrics containing cotton and polypropylene, a synthetic fiber widely used in nonwovens, after controlled exposure of fabrics to fungi normally found in soil. Fungi grew extensively only on cotton fibers. Fungal growth rates were highest on 100% cotton and decreased to zero on 100% polypropylene. Significant losses in strength occurred only in samples with a high cotton content. Progression of cotton fiber deterioration was followed using the microscope until only polypropylene . fibers remained in the fabrics.