Ryan Slopek

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.

Advent of Greige Cotton Non-Wovens Made using a Hydro- Entanglement Process

Using greige (scour/bleach-less) cotton, non-woven fabrics have been successfully produced by adopting conventional fiber opening, cleaning and (modified) carding machines followed by cross-lapping, pre/light needling, and hydro-entanglement (HE) on modern commercial machinery and equipment. Using standard test methods and procedures, the fabrics were evaluated for their weight, thickness, burst strength, tensile and tear failures in both machine (MD) and cross (CD) directions, and absorbency. Dimensional characteristics of the fabrics were determined before and after an ordinary wash. Microscopic examinations of the fiber/fabric surfaces before and after various conditions/degrees of H-E were conducted. Results of these preliminary research investigations have shown that a run-of-the-mill greige cotton, processed on a conventional cotton cleaning and preparatory system, can indeed be efficiently processed on the downstream non-wovens production equipment. In addition, it has been shown that different processing conditions, especially the high-pressure (HP) hydraulic energy of the H-E system, have a considerable influence on properties of the fabrics produced. At the nominal fabric production rates deployed in the research trials, pressure greater than 100 bar (at the system’s two HP jet-heads) produces a fabric that is partially hydrophilic: a desirable attribute for many end-use applications of cotton non-wovens. Based on a previous in-house investigation, it seems that the HP (hydraulic energy) at certain levels partly removes some of the greige cotton fiber’s natural hydrophobic defensive membrane (outer-surface barrier) of heavy hydrocarbons, such as waxes, pectins, etc., thus making the fiber/fabric partially hydrophilic. Further, it has been observed that the high water pressures (HP), under otherwise similar processing conditions, tend to fracture some cotton fibers into tiny fibrils, as evidenced by scanning electron microscopy (SEM) images. These ruptured fibers, by way of exposing their inner (hydrophilic) walls, could also partly contribute to the fabric’s improved absorbency at elevated hydraulic energy levels. Furthermore, a rather unique fabric structure, comprising certain well-defined fibrous “strands and channels,” observed at elevated (HP) pressures is also deemed to partly contribute to the greige fabric’s improved wickability.

Synthesis of a novel flame retardant containing phosphorus-nitrogen and its comparison for cotton fabric

A new charring agent, a derivative of cyanuric chloride, mono-substituted, dimethyl (4,6-dichloro-1,3,5-triazin-2-yloxy)methylphosphonate (CN), was synthesized in good yield and characterized. Its flame retardant and thermogravimetric properties were compared to those of the di-substituted compound, tetramethyl (6-chloro-1,3,5-triazine-2,4-diyl)bis(oxy)bis (methylene)diphosphonate (CN-1), which was prepared in previous work. All untreated fabric showed limiting oxygen index (LOI) values of about 18 vol% oxygen in nitrogen. Fabrics treated with CN at 5–21 wt% add-ons had high LOI values of 30–40 vol%, while fabrics treated with CN-1 at 5–19 wt% add-ons had low to high LOI value of 20–36 vol%. In 45° angle flammability tests, all treated fabrics with CN and CN-1 were passed and some fabrics were not igniting at all. Thermal degradation revealed that onset of degradation and the char yield of CN compound is higher than that of CN-1. Treated fabric with CN, 21 wt% add-on, had an onset of degradation of 240 °C, while fabric treated with CN-1, 19 wt% add-on displayed an onset of degradation of 230 °C. Despite the differences in onset temperature, the two samples provided almost the same char yield at 600 °C, 35 and 36 %. With Fourier transform infrared (FTIR), samples of treated/unburned and treated/burned of CN and CN-1 showed the same functional groups and revealed the disappearance of triazine group and P-O-methyl after burning. Additionally, scanning electron microscopy (SEM) showed that both CN and CN-1 acted as flame retardants by the same mechanism and characterized the surface morphology of the flame retardant treated twill fabrics.

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 cotton pectin content and bioscouring on alkyl-dimethyl-benzyl-ammonium chloride adsorption

Previous research has shown that both the rate and the total amount of alkyl-dimethyl-benzyl-ammonium chloride (ADBAC) exhausted from a bulk solution of ADBAC are significantly greater for greige cotton nonwovens than cotton nonwovens that have been both scoured and bleached. The presence of pectin in greige cotton samples was offered as one of the possible explanations for this observed phenomenon. To elucidate the effect of pectin and cotton’s natural waxes on the adsorption of ADBAC on greige cotton nonwovens, low-weight greige nonwovens were bioscoured with a pectate lyase prior to being immersed in aqueous solutions of ADBAC. The eco-friendly scouring process was optimized for greige cotton nonwovens and the optimal process parameters were as follows: pH of 8.5, temperature of 55°C, and an incubation time of 90 minutes. Under these conditions, the amount of pectin removed from the fabrics was equivalent to that removed by traditional scouring and bleaching procedures. Pretreatment of greige cotton nonwovens with pectate lyase was found to significantly reduce the amount of ADBAC exhausted from the bulk solution. Through partial scouring via traditional and pectinase-based methods, the adsorption of ADBAC onto cotton nonwovens was found to be linearly dependent on the amount of pectin present in the fabric. Both waxes and pectin were found to play an important role in ADBAC adsorption; however, the observed effect of pectin was significantly greater than cotton’s natural waxes.

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.

Effect of web formation on properties of hydroentangled nonwoven fabrics

The aim of this study was to determine the effects of two popular web-forming technologies, viz., the Rando air-laid technology and the traditional carding and cross-laying technology, on properties of the hydroentangled nonwoven fabrics made therewith. A mill-like fiber processing study was conducted in a commercial-grade pilot plant using a variety of short staple fibers and their blends. The fibers used in the study were greige cotton, bleached cotton, cotton derivatives, and cut-staple polyester. The hydroentangled fabrics produced with the two systems were mainly evaluated for their physical and mechanical properties, absorbency, absorbency capacity, and whiteness. The study has shown that, with the exception of greige cotton linters, the greige cotton lint, greige cotton gin motes, and even greige cotton comber noils, either alone or in blend with the other fibers mentioned, can be mechanically processed into hydroentangled nonwoven fabric structures without any insurmountable difficulties. The drop...

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.

Bleaching of hydroentangled greige cotton nonwoven fabrics without scouring

Previous research had shown that processing greige cotton on a commercial-grade hydroentanglement (HE) system at a water pressure greater than 120 bar resulted in a low-weight hydrophilic nonwoven fabric. With that ability to make hydrophobic greige cotton easily wettable and hence absorbent without the conventional scouring phase, an investigation was conducted to determine whether a fabric made by hydroentangling greige cotton fibers at a high water pressure could be successfully bleached without the traditional scouring. The investigation involved production of greige cotton nonwoven fabrics at a low hydroentangling water pressure of 60 bar and at a high hydroentangling water pressure of 135 bar and their subsequent evaluations before and after scour only, one-stage bleach only, and two-stage scour and bleach. In the results, both the 60 bar and 135 bar fabrics bleached successfully in the two-stage bleaching process and yielded acceptable absorbency and whiteness values. However, when bleached in the single-stage bleaching process with no separate scour, the 135 bar fabric still produced the whiteness index almost equal to that obtained in the two-stage bleaching process and even equal to that of a fabric made with commercially scoured and bleached cotton fibers, but the 60 bar fabric yielded about 15% lower whiteness index value while its wettability-induced improved water absorbency still was comparable to that obtained via the two-stage bleaching. This shows that a hydroentangled greige cotton fabric produced at a high enough water pressure (hydro energy) could be bleached satisfactorily without the traditional scouring chemicals and that a fabric produced even at a lower water pressure and bleached without scouring could still be satisfactory for subsequent aqueous treatments for certain end-use applications where the whiteness may not be as critical as the absorbency.