Part II: Centrifuge Studies

Welo, Lars A.; Ziifle, Hilda M.; McDonald, Allan W.

doi:10.1177/004051755202200404

Cited by 56 publications

(16 citation statements)

References 6 publications

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“…The centrifuge technique is essentially that described by Welo et al [22]. It consists of wetting the samples in boiling water and allowing them to stand and swell overnight at room temperature, or soaking them for 2 hrs.…”

Section: Methods Employedmentioning

confidence: 99%

“…Saponification to 23% acetyl content was accompanied by two other significant changes from the original properties: the yellow-dyeing rot-resistant fiber became green-dyeing as well as rot-susceptible; there was a restoration of swelling capacity. For example, the swelling of an untreated cotton yarn was represented by 38% water retention in the centrifuge test [22], that of the product of direct acetylation to 23 % acetyl content was 23 % (retention), but that of the cotton whose 23 $lc acetyl was reached by saponification was 32%.…”

Section: Deterioration Of Cellulose By Micyoor~anisvr~tsmentioning

confidence: 99%

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Chemical Substitution in Fibrous Cotton and Resistance of Substituted Cotton to Microbiological Deterioration

Goldthwait

Buras

Cooper

1951

Textile Research Journal

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The resistance for months to deterioration by microorganisms (in soil burial) of suitably acetylated fibrous cottons, some with only one-third of the hydroxyl groups substituted, depends upon the distribution of the acetyl groups as well as upon the total number of such groups present.Under usual conditions of acetylation, according to the literature, reaction takes place first in the amorphous cellulose, starting at the most accessible places. According to the present experimental acetylations and special dyeing tests, the reaction, which is probably confined at first to the amorphous cellulose, takes place along fibers in various segments and throughout cross sections rather than as a layer increasing in thickness from the surface inward. At one-third substitution the amorphous cellulose is converted to triacetate; the cotton fiber still contains about two-thirds of the original cellulose, which is present as crystalline material surrounded by acetylated cellulose. The swelling capacity of the cotton in water is greatly reduced.While the mode of attack by microorganisms is not completely understood, they apparently begin at the most readily accessible amorphous cellulose. From the literature and from the present experiments, protection by partial acetylation is believed to be due to the blocking of hydroxyl groups, the filling of spaces between chains in the amorphous cellulose, and the suppression of swelling. It represents a general method of rendering cellulose unsuitable, or at least inaccessible, as a food for microorganisms.A relatively low degree of partial saponification may detract greatly from the rot-resistance of a well-protected acetylated cotton owing to the restoration of amorphous cellulose, with loss of blocking groups and a restoration of swelling capacity. Partial methylenation by treatment with formaldehyde may impart a moderate degree of rot-resistance, which seems best explained as being due to the suppression of swelling by crosslinking. Formaldehyde-containing resins which impart rot-resistance apparently act similarly.The evidence obtained indicates that the amorphous cellulose is the part which is normally attacked, and that its ability to swell in water may be a more important factor in microbiological attack than is commonly recognized.The use of dyeing has been exemplified for qualitative tests to supplement other evidence regarding substitution and the composition and properties of substituted cottons.

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Section: Methods Employedmentioning

confidence: 99%

Section: Deterioration Of Cellulose By Micyoor~anisvr~tsmentioning

confidence: 99%

Chemical Substitution in Fibrous Cotton and Resistance of Substituted Cotton to Microbiological Deterioration

Goldthwait

Buras

Cooper

1951

Textile Research Journal

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“…Except for sample size and geometry, this method is close to a standard procedure for leather34 and resembles a swelling capacity procedure for cotton. 35 Surface water absorption was obtained by noting the time of disappearance of one drop of water released from a 2-ml syringe onto the grain surface of composites and their controls. No correction was made for evaporation error, which became important after 10 min.…”

Section: Liquid Water Absorptionmentioning

confidence: 99%

Polymer–leather composites. III. Morphology and water absorptivities of selected acrylic polymer–leather composite materials

Jordan

Carroll

Hannigan

et al. 1981

J. Appl. Polym. Sci.

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SynopsisThe morphology of composite materials made by polymerizing methyl methacrylate into chrome-tanned cattlehide was examined by both light and scanning electron microscopy. The composites were selected from a series previously prepared and characterized, and their kinetics were reported. Micrographs of the polymer phase of the composites, prepared by preferential removal of collageneous material with 6N hydrochloric acid, yielded negative replicas of the fiber conformations. These provided evidence in support of proposed mechanisms of polymer deposition for two different methods of composite preparation. One method involved emulsion polymerization of monomer into hydrated leather and the other, preferentially filling leather free space. Both light and scanning electron microscopy of all composites and replicas revealed poly(methy1 methacrylate) deposited largely in coarse aggregates around individual fibers. In emulsion systems, fiber bundles expanded with continuous deposition. No difference was observed in the morphology of bound and deposited polymers. However, high magnification of bound-polymer replicas exposed polymer surrounding some fibril traces. Deposition of polymer in the fine structure of bulk or solution prepared composites was not found; instead, all free space was occupied. A theory specifying polymer location in previous publications of this series, and extended here to define replica parameters, was abundantly supported by measured physical properties. A dominant grafting mechanism was precluded because the large domains limited points of possible attachment. Water absorptivities of emulsion prepared composites and controls were identical when the data were corrected to neat leather, although the rates were slightly perturbed. In contrast, both rate and equilibrium absorption data of the bulk and solution composites were retarded by polymer presence.

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“…The amount of water imbihed by cotton fiber can be altermed by modifying the nature of the accessible regions or by altering the amount of accessible regions. Chemical modification, cross-linking, and mercerization alter the amount of water imbibed ( 16 ) . Water of imbibition is substantially different from moisture regain at 65% relative humidity.…”

Section: Dyeing Properties Of Fabric Cross-linked Wuhmentioning

confidence: 99%

“…The procedure used for determining water of imbibition was essentially that used by Welo et al [16]. One-half-gram samples of the print cloth were cuts into 1-in.…”

Section: Dyeing Properties Of Fabric Cross-linked Wuhmentioning

confidence: 99%

Cotton Cross-Linked at Various Degrees of Fiber Swelling

Reeves

Perkins

Chance

1960

Textile Research Journal

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Wet and dry density measurements were made on a wide variety of wash-and-wear cotton fabrics and some interpretations of these values are given. Methylenated cotton was selected for more extensive fundamental study because of the simplicity of the formaldehyde cross link and the fact that formaldehyde can be reacted with cotton under greatly different conditions. Formaldehyde was used to cross link cotton print cloth at various degrees of fiber swelling by reacting in systems ranging from completely aqueous to anhydrous using hydrochloric acid as catalyst. The amount of water in the system at the time of reaction is related to the extent of fiber swotting. The extent of swelling at the time of cross-linking and the extent of cross-linking influence wet density, which may be considered to be a measure of the water swellability of a fiber. Cross-linking tends to fix or stabilize a fiber in a given state of swelling: the stabilization is more effective when the cross-linking is done in nearly anhydrous systems. The state of swelling at the time of cross-linking modifies moisture regain, water of imbibition, dyeabitity, and wet and dry wrinkle recovery. There seems to be an optimum water content in the reaction system at the time of cross-linking for maximum dry and wet wrinkle recovery. As the water content in the reaction system is increased beyond the optimum, the amount of dry wrinkle recovery becomes much less than wet wrinkle recovery. This phenomenon leads to vastly different wash-and-wear ratings of fabric.A mechanism is presented diagrammatically to explain wet and dry wrinkle recovery. The mechanism is based upon hydrogen-bond cross links, covalent-bond cross links, and the position of the two types of cross links.AL.'FHOUGH wrinkle resistant cotton fabrics have heen known for about 30 years, many of the basic principles for imparting wrinkle recovery are not too well understood. The wrinkle recovery and washand-wear characteristics of a textile are affected by its construction and by the construction of the yarns of which it is composed. However, the properties of the fiber which make tip the yarn and fabric have, perhaps, an even greater influence on wrinkle recovery and wash-and-wear properties. Cross-linking within the fiber seems to have been accepted by most researchers as the hasic requirement for wrinkle recovery. It provides an excellent way of changing many of the properties of cotton fiber. The physical properties of cross-linkeci goods are quite well known, but the principle of producing physical changes with -----.-----.. cross links within the microstructure of the fiber, which is actually responsible for the fiber properties, is not too well defined. Differences have been observed between the wrinkle recovery of cotton fabrics finished by the pad, dry, and cure process and the wrinkle recovery of fabric finished while swollen in mercerizing strength alkali solution. The first of these processes, which is often thought of as reacted in the collapsed state, imparts wet and dry wrinkle recovery....

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Part II: Centrifuge Studies

Cited by 56 publications

References 6 publications

Chemical Substitution in Fibrous Cotton and Resistance of Substituted Cotton to Microbiological Deterioration

Chemical Substitution in Fibrous Cotton and Resistance of Substituted Cotton to Microbiological Deterioration

Polymer–leather composites. III. Morphology and water absorptivities of selected acrylic polymer–leather composite materials

Cotton Cross-Linked at Various Degrees of Fiber Swelling

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