Paul Sawhney

Effect of water pressure on absorbency of hydroentangled greige cotton non-woven fabrics

A greige (non-bleached) cotton lint was used to fabricate non-woven fabrics on a Fleissner MiniJet, using different water pressures for the fiber entanglements. The greige cotton and its hydroentangled non-woven fabrics were primarily tested for their hexane extracts (waxes) and water-soluble (sugars) contents using the AATCC TM97 Standard Extraction Test. Tests have shown that a water pressure of 125 Bar or higher almost totally removed the greige cotton’s inherent hydrophobic waxes and water-soluble sugars. This discovery is a significant milestone in the development of greige cotton-based non-wovens because it could change the greige cotton’s native hydrophobic character into a desirable hydrophilic character for many end-uses. In fact, the AATCC Test Method 79-2007 has confirmed that the greige cotton non-wovens fabricated with high water pressure of 125 Bar are absorbent, as indicated by the 1-second time or less it took for the water drop to completely diffuse onto the fabric surface.

A comparative study of nonwoven fabrics made with two distinctly different forms of greige cotton lint

Two sets of nonwoven fabrics of nominal density, 80 g/m2, have been produced on the pilot plant equipment comparable to that used in commercial production, using two different forms of greige (non-bleached) cotton lint. One was regular cotton taken from a randomly picked classical bale and the other was mechanically pre-cleaned cotton produced by a well known US cotton producer and ginner. The fabrics were produced by using a pre-needling, needlepunch system and a hydroentanglement system. Some of the fabric in each set was scoured only and some was both scoured and bleached. All the fabrics were tested for a comparison of their typical physical and mechanical properties, which, along with the fiber and fabric processing metrics, are discussed in this article. The information obtained from this comparative study has shown that although both the regular and the pre-cleaned greige cottons can be satisfactorily processed on the conventional cotton opening, cleaning and carding equipment to ultimately produce acceptable nonwoven fabrics, the pre-cleaned cotton may be processed without the traditional cotton cleaning/carding equipment that is not available at almost all nonwovens manufacturing entities today. A ‘nonwovens card’ (i.e., without the revolving flats) should be adequate to efficiently card the pre-cleaned greige cotton, since the latter is indeed very clean to start with.

Effect of polyester blends in hydroentangled raw and bleached cotton nonwoven fabrics on the adsorption of alkyl-dimethyl-benzyl-ammonium chloride

The adsorption kinetics and isotherms of alkyl-dimethyl-benzyl-ammonium chloride (ADBAC), a cationic surfactant commonly employed as an antimicrobial agent, on hydroentangled nonwoven fabrics (applicable for wipes) including raw cotton, bleached cotton, and their blends with polyester (PES) were studied at room temperature. The adsorption kinetics of ADBAC on all nonwoven fabrics was best described by the pseudo-first-order kinetic model. Unlike bleached cotton/PES blends, the equilibrium adsorption capacities of ADBAC on raw cotton/PES blends were enhanced in comparison with predictions based on the binary mixing rule. The adsorption rates for raw cotton, determined by the KASRA (kinetics of adsorption study in the regions with constant adsorption acceleration) model and Elovich equation, were significantly greater than those for bleached cotton, resulting in a rapid decrease of adsorption rates when blending with PES, which has a negligible interaction with ADBAC. This distinctive adsorption property of raw cotton was attributed to its unique surface characteristics induced by the hydroentangling process: retained pectin, partial removal of waxes, and surface fibrillation, which enhance electrostatic interaction, hydrophobic interaction, and accessible surface area to ADBAC, respectively. In adsorption isotherms, raw cotton/PES blends exhibited a non-linear decrease in maximum adsorption capacity and monolayer adsorption capacity, calculated by the Langmuir and Langmuir-type equations, respectively, as a function of PES blend ratio.

Comparison of biodegradation of low-weight hydroentangled raw cotton nonwoven fabric and that of commonly used disposable nonwoven fabrics in aerobic Captina silt loam soil

The increasing use of synthetic disposable nonwoven products generates a large amount of non-biodegradable solid waste. In an effort to enhance the use of raw cotton in nonwoven wipes applications, this study compares the biodegradation of low-weight nonwoven fabrics (around 50 g/m2) made of mechanically pre-cleaned raw cotton, rayon, polypropylene (PP), and polylactic acid (PLA) in a Captina silt loam soil. The biodegradation rates of raw cotton and rayon fabrics were fitted to the first-order kinetics model with half-life values of 12.6 and 7.6 days, respectively. The slightly faster disintegration of cellulose structure for rayon was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectra, and distinct morphological changes in the fiber (cracks and breakage were prevalent in raw cotton, whereas the thinning and merging of fibers occurred in rayon) were observed during their biodegradation. PLA and PP nonwoven fabrics exhibited no weight loss during the burial periods studied, but showed some evidence of oxidation in ATR-FTIR spectra. The breaking and burst strengths of PLA fabric decreased by 45% and 23% of the original strengths, respectively, while neither significantly decreased in PP fabric. The results suggest that mixing raw cotton or rayon low-weight nonwoven wastes with surface soil provides an alternative disposal method, but this land application could not be recommended for PLA and PP nonwoven wastes.

Electrokinetic properties of functional layers in absorbent incontinence nonwoven products

Incontinence control through the use of well designed nonwoven materials is a rapidly growing area of interest. Analysis of the streaming zeta potential, absorbance capacity and moisture content measurements of absorbent layers in incontinence materials is a useful approach to evaluation and design. Using this approach, electrokinetic properties can be used to demonstrate the role of fiber surface polarity, swelling, and water uptake in the mechanism of incontinence control. By applying electrochemical double layer analysis to functional layers of absorbent incontinence products, the polar charge differences between cover stock, the acquisition/distribution layer (ADL) and the absorbent core were characterized. The aqueous fiber polarity is characterized from pH titration plots that give zeta plateau (ζplateau) values for each absorbent layer. The ζplateau value assigns the relative hydrophilic/hydrophobic (amphiphilic) character of the cover stock and ADL. Delta zeta (Δζ) and moisture content are applied to determine the functional value of fluid acquisition due to swelling and moisture absorption. Structure/function mechanisms are proposed for urine uptake relative to volume, pH and fluid transport in the cover stock and ADL of heavy, moderate, light incontinence pads and adult incontinence underwear. Using an electrokinetic analysis as a model to describe the mechanism of urine transport in absorbent incontinence materials makes possible the distinction of absorbent material design differences based on fiber charge, swelling, and absorption capacity. The electrokinetic model approach to absorbent incontinence material analysis and design is discussed for its potential applications.

Adsorption of alkyl-dimethyl-benzyl-ammonium chloride on differently pretreated non-woven cotton substrates

The adsorption of alkyl-dimethyl-benzyl-ammonium chloride (ADBAC), a cationic surfactant commonly employed as an antimicrobial agent, on greige, alkaline scoured, and bleached non-woven cotton fabrics was investigated at varying surfactant concentrations using ultraviolet-visible spectroscopy. Results show greige cotton non-wovens adsorb roughly three times the ADBAC in aqueous solution than bleached cotton and 1.5 times more than scoured cotton non-wovens. At a constant ADBAC concentration of 0.625 g/l, the rate of surfactant adsorption approached equilibrium after 35 minutes in all fabrics studied. Increasing surfactant concentration increased the total mass of ADBAC exhausted onto the cotton fabrics at equilibrium. Adsorption of ADBAC on cotton fabrics can be attributed to bulk entrapment, dispersion forces, and hydrophobic and electrostatic interactions. Polyester fiber was blended with greige and bleached cotton fibers to further elucidate the adsorption of ADBAC. A linear decrease in the amount of surfactant exhausted was observed as the amount of polyester added to the blend was increased. This indicates that the adsorption of ADBAC on cotton fabrics is primarily an effect of surface interactions of the cotton fiber with the surfactant molecules rather than absorption via bulk entrapment. The results of this research can aid in the development of cotton-based antimicrobial wipes.

Electrokinetic analysis of hydroentangled greige cotton–synthetic fiber blends for absorbent technologies

Through nonwoven hydroentanglement of greige cotton blends with polyester and nylon, varying degrees of fiber surface polarity, swelling, and absorbance can be achieved. Electrokinetic properties of nonwoven blends made with Ultra Clean™ cotton (100% greige or virgin cotton) and polyester or nylon in 40:60 and 60:40 ratios demonstrated distinct differences in charge, swell, and per-cent moisture uptake capability. An electrochemical double layer analysis of charge based on a pH titration (pH 1.5–11 in 1 mM KCl) was employed to measure the relative fiber and fabric surface polarity (ζplateau), which ranged from −60 to −26 millivolts. A linear relationship of fiber swelling (Δζ) and per cent moisture content is apparent when greige cotton and synthetic fibers are blended. Water contact angles revealed that the cotton/synthetic fiber blends were hydrophobic (contact angle >80°) while retaining significant absorbency. The greige cotton/synthetic nonwoven materials, however, possess absorbent properties characterized by varying degrees of moisture uptake, fiber polarity, and swelling attributes similar to absorbent fluid transport materials present in the layers of incontinence products. Electrokinetic properties of the blended greige cotton/synthetic nonwovens are correlated to absorbent incontinence materials.

Greige cotton comber noils for sustainable nonwovens

The aim of this study was to determine feasibility of utilizing greige (non-bleached) cotton comber noils in the development of hydroentangled cotton fabrics for certain end-use products and thereby to promote an economically and environmentally efficient utilization of cotton in sustainable textile products. The data from the feasibility study show that greige comber noils can be efficiently processed into nonwoven fabrics using an air-laid system for preparing a fibrous batt to feed a down-stream hydroentangling system. Furthermore, the study has shown that, for certain specific end-use applications where bleaching is required, the hydroentangled greige cotton fabric can be efficiently bleached without the customary costly and time consuming cotton scouring process. The elimination of the scouring process was made possible by the removal of cottons natural hydrophobic contaminants (waxes) by optimizing the hydraulic pressure/energy metrics of the hydroentanglement process of producing nonwoven fabrics.

An Assessment of Surface Properties and Moisture Uptake of Nonwoven Fabrics from Ginning By-products

Greige (raw) cotton by-products resulting from cotton ginning and mill processes have long been bleached for use in absorbent nonwoven products. The potential to use greige cotton by-products as an economical source for absorbent nonwoven blends is explored. The nonwoven hydroentanglement of greige cotton lint with cot‐ ton gin motes and comber noils blends was analyzed for fiber surface polarity, swel‐ ling, and absorbance to assess properties with potential usefulness in absorbent nonwovens. The electrokinetic analysis of the fabric surface gives a composite picture of the relative hydrophilic/hydrophobic polarity absorbency and swelling properties. Nonwoven fabrics made with cleaned greige cotton lint separately blended with comber noils and ginning motes at 40:60 and 60:40 blend ratios demonstrated charge, swell, and percent moisture uptake profiles that are characteristic of the fabrics’ crys‐ talline/amorphous cellulosic content with some variance in swelling properties. How‐ ever, cellulose crystallite size varied. X-ray diffraction patterns of the three different cotton constituents displayed similar crystalline cellulose compositions. An electro‐ chemical double-layer analysis of charge based on a pH titration (ζplateau) was em‐ ployed to measure the relative fiber and fabric surface polarity which varied slightly between -21 and -29 mV. A relationship of fiber swelling (∆ζ) and percent moisture content is apparent when greige cotton lint and other fibers are blended. The blended nonwoven materials possess absorbent properties characterized by similar moisture uptake (7.1-9.5 %) and fiber polarity, but some variation in swelling is based on the by-product additive and its percent content. The crystallinity, electrokinetic, and wa‐ ter binding properties of the nonwoven by-product materials are discussed in the con‐ text of the molecular features water, cellulose, and greige cotton components that enhance potential uses as absorbent nonwoven end-use products.

Whiteness and absorbency of hydroentangled cotton-based nonwoven fabrics of different constituent fibers and fiber blends

The aim of this research is to develop greige (raw/non-bleached) cotton-containing nonwoven fabrics that likely would be competitive in quality, cost and performance to existing products that presently and predominantly use man-made fibers and some bleached cotton for wipes and other similar end-use nonwoven products. Since the whiteness and absorbency of these end-use products generally are the most desired and perhaps even critical attributes, the research was mainly focused on attaining these attributes by exploring various choices and optimum use of a variety of cost-effective cotton fibers and the blends thereof with other fibers. Nonwoven fabrics were produced, via a modern hydroentanglement system, with possible choices of using several types of cotton fibers, including the greige cotton lint and certain of its co-products such as gin motes and comber noils, and their various blends with polyester and nylon staple fibers. Bleached cotton was also used to produce an equivalent fabric for comparison....