Density of Modified Cottons Determined with a Gradient Column

Orr, Rollin S.; Weiss, Louis C.; Moore, Harry B.; Grant, James N.

doi:10.1177/004051755502500703

Cited by 70 publications

(16 citation statements)

References 26 publications

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“…Yet it is very important to know the precise density of polymeric materials in order to understand their structure and physical properties, e.g., crystallinity and crystallization. Polymer density can be measured us ing a density gradient column (5,6). However, to mea sure density accurately, the measuring liquid in the de nsity gradient column must completely fill even the voids.…”

Section: Introductionmentioning

confidence: 99%

Permeation Mechanism of Deaerated Water into Textile Surface Confirmed by Fiber Density Measurements.

et al. 1996

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Section: Introductionmentioning

confidence: 99%

Permeation Mechanism of Deaerated Water into Textile Surface Confirmed by Fiber Density Measurements.

et al. 1996

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“…Density was determined on'small portions of the reacted samples by the method of Orr and others [ 10] , using calibrated glass beads at close density intervals, and xylene-carbon tetrachloride as the media. The samples were thoroughly driecl in a desiccator and then hoiled 15-20 min.…”

Section: Methodsmentioning

confidence: 99%

Changes in Fine Structure and Mechanical Properties Induced by Cyanoethylation of Cotton Yarns

Stanonis

Harbrink

Creely

1960

Textile Research Journal

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Cotton yarns were impregnated with 6% sodium hydroxide and reacted in the relaxed state with acrylonitrile at 60° ('. and different periods of time up to 60 min. to give products with degrees of suhstitution up to 2.6 cyanoethyl groups per anhydroglucose unit.As substitution increases, the x-ray diffraction pattern shows only slight alteration until substitution has exceeded 1.1, after which the crystalline structure rapidly gives way to ' an amorphous structure, complete at about DS = 2.0. At the same time density decreases nearly linearly with substitution. At the stage where the product becomes essentially amorphous, it can be annealed at temperatures of about 175° C. into a new pattern characteristic of cyanoethyl cellulose. This annealing is accompanied by a substantial density increase. Stress relaxation of the cyanoethylated yarns at a substitution of 1.1 suggests a glass-rubber transition point about 140° C. which becomes more distinct and moves to lower temperatures as substitution increases. At a substitution of about 2.0 the stress relaxation reaches its lowest value (about 4% of the value at 20° C.) at the highest temperatures tested (220° C.). With further substitution a minimum relaxation at an intermediate temperature is followed by increasing stress as the temperature is raised. This effect is associated with crystallization. Breaking strength increases slightly at low substitutions but decreases then to less than 50% for the highest substitutions. Elongation at break increases gradually, exceeding 100% above the control at DS = 2 and above.Tensile stiffness decreases to about 3% of its initial value. Work of rupture and recovery show considerable decreases below DS = 2, but sharp rises between 2.0 and 2.6. Immediate elastic recovery is little affected below DS = 2, but rises above this. Delayed elastic recovery shows continuous improvement as substitution increases, eventually exceeding the control by nearly 50%.

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“…Each of the fabrics used in Figure 5 to develop the curve contained 0.8% combined formaldehyde so as to eliminate the effects of extent of cross-linking. 11 'al~r of lnihihition of Cross-Linked Cotton When cotton is wet in water, it imbibes a considerable volume of the water. The imbibition is accompanied by a large increase in volume of the fiber, caused by a considerable internal pressure.…”

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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Density of Modified Cottons Determined with a Gradient Column

Cited by 70 publications

References 26 publications

Permeation Mechanism of Deaerated Water into Textile Surface Confirmed by Fiber Density Measurements.

Permeation Mechanism of Deaerated Water into Textile Surface Confirmed by Fiber Density Measurements.

Changes in Fine Structure and Mechanical Properties Induced by Cyanoethylation of Cotton Yarns

Cotton Cross-Linked at Various Degrees of Fiber Swelling

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