Blanche R. Porter

Survey of Cotton Fiber Swelling in Various Liquids by Use of the Yarn Untwisting Test

The relative swelling of cotton in 67 organic liquids and aqueous solutions of 14 inorganic compounds was evaluated by observing the number of revolutions of a singles yarn of Iquitos variety during untwisting in a 3-min post-immersion interval. Aqueous dilutions of the lower alcohols, two organic acids, acetone, and ethanolamine were also tested. The yarn was used in the unpurified state, after scouring and after scouring and mercerization. The relative swelling of cotton in 17 of the liquids determined by this untwisting technique was in qualitative agreement with values found by microscopi cal measurements of changes in width of fibers taken from the scoured and mercerized yarn. Qualitative agreement with values reported in the literature for measurement of swelling by other techniques was also established. The effects of some experimental variables wrere investigated.

Soil-Resistant Finish for Cotton Fabrics

Short communications in the form of Letters to the Editor are intended to provide prompt publication of significant new research results and to permit an exchange of views on papers previously published in the JOURNAL. These communications are not submitted to formal review as are research papers, and the editors do not assume any share of the author’s responsibility for the information given or the opinions expressed. When work previously published in the JOURNAL is the subject of critical comment, the authors of the original paper are given

The Surface of the Cotton Fiber Part III: Effects of Modification on Soil Resistance

Experiments designed to complement microscopical studies and to attempt a practical evaluation of the effectiveness of various agents which impart resistance to dry soil are reported. Various methods of applying soil to fabric were evaluated, as was the ef fectiveness of a number of soil retardants. Soils included carbon blacks of a range of particle sizes, a natural clay, and a synthetic soil whose formula approximated the com position of natural soil, containing fatty materials. Fabrics were also soiled by foot traffic on the floor. Results were interpreted from reflectance data and from radioactive tracer assays of weight of soil takeup. In attempting to elucidate the mechanism of dry soiling. the effects of textile construction, electrical charge on the fiber, particle size of soil as related to topography of fiber surface, surface hardness, reducing surface rough ness. and lowering surface energy were considered. It was shown that soil takeup is directly related to specific surface. It was found that grey cotton is slightly more re sistant to soil than bleached cotton, and that increased smoothness of fiber. even to com plete obliteration of native rugosities, did not necessarily impart soil resistance to cotton fabrics. The most successful types of antisoiling agents for dry soils appear to be col loidal particulate applications such as silica or alumina, and additive finishes which lower surface energy of the tiber. Only a few of the typical commercially available soil re tardants were used in these studies. The project was a short term one and the experi ments were designed for the study of the mechanism of soiling of cotton textiles which would be subject to in-place cleauing. Many new soil retardants were marketed after the experiments had been initiated.

The Surface of Cotton Fibers: Part IV: Distribution of Dry Soil

The location of soiling agents such as colloidal and activated carbon, floor soil. a syn thetic soil, and a clay on gray and modified plain weave cotton fabrics soiled under con trolled conditions was determined by light and electron microscopical examination. Cross and fine geometry of fabric and fiber play a major role in determining the dis tribution of soil in most cases. The mechanical entrapment of soil particles and ag glomerates between fibers near the surface of the fabric is repeated in the accumulation of soil in the natural or induced irregularities of the native and modified fiber surface. The presence of soft films on the fiber surface extends the quantity of soil and its dis tribution. Sorption of the soil particles on apparently smooth areas of the fiber also occurs to a significant extent.

Changes in Microporous Structure of Modified Cotton Fabrics Water-Swollen After Creaseproofing or other Modification

are slightly more than one half of the total damage. Incidentally, the chemical damage due to laundering, i.e., item (i) of Table II is only one third of the total damage, thereby conforming to the recommended conditions for satisfactory laundering L5]. . While the techniques and methods reported here appear to have wider applicability for a clearer appraisal of chemical damage in relation to mechanical damage in service wear, it should be cautioned that the actual estimates given here are only indicative and will vary in relative importance, depending on conditions of

Effect of Cellulase on Cotton Fiber Microstructure Part I: Degradation by Cellulase in Fungal Growth Filtrates

Electron microscopical studies of changes in cotton fiber microstructure, after ex posure of the fibers to the cellulase in filtrates prepared from cultures of Myrothecium verrucaria, showed evidence of the transverse, jagged cuts into the cellulose structure previously seen by cytical microscopy. The degradation appeared localized in areas along the length of the fiber which were not related to any recognized component of fiber structure. Micrographs of fragmented, degraded fibers showed etching of the macro- fibrils of the sheets of secondary wall and a sharpening of the image of the individual microfibrils. Continued enzyme attack produced smaller fragments and hydrocellulose- like particles. Measurements of changes in tensile strength, swelling in alkali, and in glucose yield were correlated with changes in microstructure. The extent of fiber degradation by cellulolytic culture filtrates was limited and could be continued only if fibers were swollen between filtrate exposures. No evidence of damage to the cellulose structure was seen which could not be explained hy hydrolysis at the β-1,4-glucosidic linkage.

Changes in Fibrillate Structures of Cottons on Hydrolysis and Oxidation

Four modified cottons—mercerized sliver, a partially acetylated fabric, and two cross- linked fabries—were exposed to hydrochloric and sulfuric acids, sodium periodate, nitro gen tetroxide, hydrogen peroxide, ozone, and heat for intervals selected to illustrate early and late stages of fiber degradation. Electron micrographs were made in order to observe changes in tihrillate structure. Parallel changes in moisture regain, crystallinity indices. copper number, carboxyl content, and, in some samples, degree of polymerization were measured. Changes in fibrillate structure and other properties were found to be related to the type of modification and the resistance of substituent groups to the degrad ing agents, the activity of these, agents, and to duration of exposure. In general, where substituents were not removed, degradation decreased with increase in content of sub stituent groups in the chemically modified cottons. Mercerization. without further modi fication, caused an increase in rate of degradation.

Measurement of Changes in Thickness of Compressed Cotton Samples During Swelling

An apparatus is described for measurement of vertical dimension of cotton samples immersed in water, methanol, tiquid ammonia, and NaOH solution. Increase in thickness of cotton showed recovery from compression and swelling. The increases were automatically recorded as a function of time by a chart recorder.

A Program of Microscopical Research on Soiling in Cotton

Blanche R. Porter, Charles L. Peacock, Anna T. Moore, Verne W. Tripp, and Mary L. Rollins Southern Regional Research Laboratory, New Orleans, Louisiana Toward the ultimate goal of a built-in resistivity to soiling, investigations have been initiated to develop basic information on the mechanism of soiling of cotton fibers. Electron microscope studies of surface replicas of individual fibers have shown the frequency, depth, and size of wrinkles and grooves which are characteristic of untreated cotton, and the relation of these irregularities to entrapment of soil particles of certain ranges of particle size. The effects of bleaching and mercerization on soiling have been compared, and the changes brought about by certain commercial soil retardants or other treatments on fiber surface roughness have been observed. The relation of these findings to the ease of soiling are currently being studied, but tests are incomplete. Preliminary observations indicate that soil resistance involves geometric or physical saturation of soil sites on the fiber surface that normally would be occupied by soil particles. The comparative excellence of soil retardants of the colloidal metallic oxide type lends credence to this theory. Water repellants of the substituted ketene type and the silicone and acrylic resins used in these experiments, although they effectively cover the natural fiber surface rugosities, also, apparently, present a &dquo;tacky&dquo; surface for holding soil. This is a progress report of initial phases of a rather complex study. Findings and conclusions will be reported in detail at the completion of the investigation.

Effect of Cellulase on Cotton Fiber Microstructure

Electron microscopical studies of changes in cotton fiber microstructure, after ex posure of the fibers to the cellulase in filtrates prepared from cultures of Myrothecium verrucaria, showed evidence of the transverse, jagged cuts into the cellulose structure previously seen by cytical microscopy. The degradation appeared localized in areas along the length of the fiber which were not related to any recognized component of fiber structure. Micrographs of fragmented, degraded fibers showed etching of the macro- fibrils of the sheets of secondary wall and a sharpening of the image of the individual microfibrils. Continued enzyme attack produced smaller fragments and hydrocellulose- like particles. Measurements of changes in tensile strength, swelling in alkali, and in glucose yield were correlated with changes in microstructure. The extent of fiber degradation by cellulolytic culture filtrates was limited and could be continued only if fibers were swollen between filtrate exposures. No evidence of damage to the cellulose structure was seen which could not be explained hy hydrolysis at the β-1,4-glucosidic linkage.