1a. Objectives (from AD-416):
Objective 1: Enhance and promote cotton’s natural sustainability features in the context of disposable nonwovens applications. Objective 2: Characterize and correlate the relationships among the cotton fiber quality parameters, the nonwovens process-ability, and the final fabric performance characteristics. Objective 3: Develop and optimize hydro-entanglement chemistry and process parameters for cotton fiber and the nonwoven fabrics thus produced. Objective 4: Develop innovative end-use functional technologies that enable increases in the amount and value of cotton used in nonwoven applications. Objective 5: Develop processes for producing nonwoven fabrics from greige cotton.
1b. Approach (from AD-416):
The ultimate goal of this research project is to increase value-added utilization of cotton via development of performance-specific nonwoven products containing cotton. The term "cotton" used here includes cotton lint, ginning motes and linters, comber noils, processing wastes, recycled cotton, and the like. The research approaches broadly involve 1) characterization of fibers and fiber blends to be used; 2) selection of optimum processes and conditions for fiber opening, cleaning, and web formation; 3) selection of appropriate nonwovens production system; 4) evaluation of process and product performances; 5) physical, mechanical and/or chemical modifications of nonwoven products to attain and/or enhance the required functionality; 6) within the scope of the project, determine biodegradability, cost-effectiveness, environmental impact and sustainability of the products produced; and 7) disseminate the research results via publications, technical forums, and technology transfer to industry. Specifically, the research involves developing fiber-processing technology to obtain supply of clean greige/virgin (scour/bleach-less) cotton that is appropriate for the intended end-use application. Most of the existing manufacturers of nonwoven rollgoods do not have the resources, facilities and/or technical expertise to open and clean supply bales of greige cotton(s). It is imperative to develop a protocol that would enable the nonwovens manufacturers to either both open and clean cotton in their in-house facilities or obtain some readily available pre-cleaned cotton. Depending on individual products, we will determine efficient routes for processing cotton into a clean web for downstream processes. SRRC has the equipment, including cotton carding, to thoroughly open and clean virgin cotton and also the resources to procure and process pre-cleaned supply cottons (say, UltrcleanTM cotton). The preferred research focus is on using greige cotton, instead of bleached cotton that currently is primarily used in premium quality nonwovens. However, nonwoven fabrics made with cleaned greige cotton may be satisfactorily scoured and bleached, if necessary. To determine which cotton would be most cost effective for certain specific end-use applications, certain experimental investigations and small-scale industry-like production trials have been planned. They involve studies of the fiber, process and product metrics and their relationships. Research efforts will be redirected to improve any marginal outcomes. In general, carding process will be deployed to form a web for the downstream needle-punching and/or hydroentangling systems of producing nonwoven products. Optimizations of the N-P and H-E processes and products will be sought through planned investigations. Comprehensive testing of in-process products and end-products will be conducted to realistically evaluate the research outcomes. Statistical tools will be used for reliability of the results. Issues concerning the biodegradability, disposability, environmental impact, safety, government/industry-compliance,and cost-analysis will only be conducted to the extent feasible within the scope of the project.
3. Progress Report:
This report highlights the second year research accomplishments made by Agricultural Research Service (ARS) scientists at the Southern Regional Research Center (SRRC) in New Orleans, Louisiana, on the development, chemical treatment, and modification of cotton-based nonwoven products. Although the installation of the fiber processing equipment is an ongoing process, numerous trials have been conducted on the existing equipment to optimize the machinery and process parameters for the production of cotton-based nonwovens. These studies have revealed that pre-cleaned raw/greige (non-bleached) cotton can successfully be used to produce nonwoven substrates for commercial end-use applications, such as wipes, medical products, and perhaps even apparel. Thousands of yards of various cotton- and cotton blend-based nonwoven fabrics have been produced, some of which are currently being evaluated by commercial entities. Specifically, comparative biodegradability studies have shown that cotton-based fabrics biodegrade faster than synthetic nonwovens, and consequently, an exposure to simple surface soil may be an efficient and eco-friendly means of disposal. In another study, discounted cottons including cotton ginning and processing byproducts were successfully processed and converted into hydroentangled nonwoven fabrics of considerable strength. In separate studies conducted on the commercial-grade hydroentanlement equipment, it was revealed that hydroentangled greige cotton-based nonwovens processed at certain conditions could be bleached, dyed, and even specially finished without the traditional chemical and costly scouring process. Separately, under a renewed Cooperative Research and Development Agreement with a U.S. cotton producer and ginner, it was found that unlike the traditional textile process of weaving, the production of cotton nonwovens is mostly independent of cotton fiber properties (within their standard ranges investigated). In addition, laundering these cotton-based nonwovens demonstrated the fabrics retain approximately 80% of their original mechanical integrity and dimensional stability after 20 cycles. Research on improving the flame resistance of cotton nonwovens has effectively shown that a urea additive is a cost effective alternative to diammonium phosphate in specific flame retardants. In yet another study on the development of cotton-based antimicrobial wipes, it was determined that greige cotton adsorbs three times more of antimicrobial agent than bleached cotton nonwovens. The adsorption of antimicrobial agent on both greige and bleached cotton nonwovens can be significantly reduced via chemical treatment of the fabrics and modification of the antimicrobial solution. Research on cotton fiber bioloads to improve cotton’s status in nonwovens has yielded valuable new information on the microbial and bacterial content of greige and hydroentangled cottons, which supports the expanded use of cotton in nonwovens and has resulted in one and one-half Cooperative Research and Development Agreement(s) with Cotton Incorporated.
1. Effect of water pressure in the hydroentanglement of greige cotton. Greige raw cotton naturally has high-molecular hydrocarbons (waxes) that must be removed, through a rather costly and environmentally-sensitive chemical process called scouring, in the production of almost all cotton-based textile end-use products. Agricultural Research Service (ARS) scientists at Southern Regional Research Center (SRRC) in New Orleans, Louisiana, have discovered that the hydroentangling (high) water pressure used in fabricating cotton nonwoven fabrics plays a significant role in removing the waxes without involving the traditional scouring process. This is a significant research milestone that will contribute to saving money, energy, chemicals and, above all, our planet’s environment. The nonwovens industry leaders have expressed great interest in this development, which is expected to encourage increased use of cotton in nonwovens. The research was published in the Textile Research Journal (TRJ) and also highlighted in the industry’s popular journals. In a related, secondary development, a miniature research tool of converting, in minutes, a small sample of any staple fiber into a hydroentangled nonwoven fabric was developed, using a commercial-grade nonwovens (tabletop) lab card (with fixed plates instead of revolving flats of a cotton card) placed in tandem (series/line) with an in-house-fabricated, prototype hydroentanglement system. This research tool will be used to conduct preliminary investigative projects that otherwise would be costly, time-consuming and perhaps even unsafe when conducted on the commercial-grade pilot plant equipment that is expensive and prone to possible damage due to unproven chemicals, procedures and practices.
2. Efficient utilization of discounted cotton and cotton co-products. Each year, substantial quantity of cotton (crop) is discounted in quality, which subsequently and substantially reduces its selling price since the discounted cotton generally is unsuitable for efficient processing and products for traditional textiles involving spinning and weaving yarns. Research conducted by Agricultural Research Service (ARS) scientists at Southern Regional Research Center (SRRC) in New Orleans, Louisiana, has revealed that the quality-discounted cotton as well as the cotton-ginning and cotton-textile-processing byproducts, such as gin motes and comber noils, respectively, can be efficiently processed into viable 'nonwoven' products, using the hydroentanglement system of fabricating the fabrics. The research seemingly has advanced and expanded the value-added utilization of cotton that is considerably discounted in price.
3. Durable cotton nonwovens. Nonwoven end-use products for a long time have been thought and actually termed 'disposable,' since they generally are good for one, short or long, use only. The Agricultural Research Service (ARS) conducted at Southern Regional Research Center (SRRC) in New Orleans, Louisiana, has changed that universal concept by demonstrating for the first time ever that cotton nonwoven fabrics made with an optimized process of hydroentanglement can, indeed, be strong, wet-finish able, launderable for up to 20 (and, in some cases, even 40) household washing and drying cycles and, hence, they can be durable in multiple uses. The research has the industry and academia rethink cotton nonwovens not only as the 'disposables' but also as the 'durable' textile products that can be repeatedly washed and dried with minimal changes in their properties and functionality.
4. Adsorption of antimicrobial agents (quats) on cotton compared to synthetic fibers. Most antimicrobial wipes available in the market today use synthetic and manmade fibers, although some pulp is also used. Use, if at all, of natural cotton fiber is minimal in these end-use products and applications, mainly because of the strong adherence of quat onto cotton fiber, which, consequently, resists the desired ease and functionality of dispensing the quat when the quat-loaded wipe is wiped onto a contaminated surface for decontamination. Various cotton, synthetic, rayon, and cotton blend-based nonwoven fabrics were immersed in antimicrobial quat solutions of varying concentrations for a variety of liquor ratios and times. Cotton, both bleached and greige versions, and rayon adsorbed significant amounts of the antimicrobial agent, with the greige cotton and rayon adsorbing nearly three times more antimicrobial agent than the bleached cotton nonwovens. The underlying issue was how to optimally reduce adsorption of quats by greige cotton, while improving their ease and effectiveness of release onto a contaminated surface. The greige cotton fabrics were bioscoured using an enzyme (pectinase) and/or boiled to remove the majority of greige cotton’s natural waxes. It was discovered that cotton’s pectin content and to a lesser extent wax content played a significant role in the adsorption of antimicrobial agent by the greige cotton nonwovens. It was also discovered that addition of alcohol, electrolytes, and a nonionic surfactant to the antimicrobial solution greatly reduced and/or even completely eliminated the adsorption of the antimicrobial agent onto both the greige and bleached cotton nonwovens. The research has led to yet a new potential use of pre-cleaned greige cotton in the antimicrobial nonwoven products.
5. Waste management for a better tomorrow. The waste management of commonly used nonwoven products made with synthetic fibers largely relies on land-filling and incineration, which cause serious environmental pollution and related problems. In collaboration with the University of Arkansas, a study conducted by the Agricultural Research Service (ARS) scientists at Southern Regional Research Center (SRRC) in New Orleans, Louisiana, has shown that cotton-based nonwoven fabrics, compared to those made with synthetic fibers, biodegrade much more rapidly when subjected to aerobic soil. The attentuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectra and scanning electron microscope (SEM)analyses revealed that the cotton fabric degraded in 14 days and almost totally disintegrated within 21 days of aerobic soil burial, whereas the fabrics made with synthetic/manmade fibers showed little or no biodegradability even 140 days of the burial. This is an interesting finding which may lead to 'composting' as an efficient and eco-friendly alternative for safe disposal of cotton-based nonwovens.
6. A totally novel chemical technology to make cotton textiles flame-suppressant. Making cotton textiles flame/fire retardant (FR) has been a serious challenge for many years, worldwide. Diligent research approaches by Agricultural Research Service (ARS) scientists until now had been directed towards investigations of FR chemicals that were costly and soluble only in organic solvents, which obviously were neither economical and nor eco-friendly. The Agricultural Research Service (ARS) scientists at Southern Regional Research Center (SRRC) in New Orleans, Louisiana, recently have discovered new molecules that are less expensive and water soluble and impart acceptable degree of fire retardancty/protection to cotton fabrics. The research has attracted the attention of industrial stakeholders who are interested in FR cotton for a variety of consumer, industrial, furnishing and household products.
7. Cotton-based nanotechnology. Nanotechnology is the wave of the future. Agricultural Research Service (ARS) scientists at the Southern Regional Research Center (SRRC) in New Orleans, Louisiana, have developed phosphorous-nitrogen rich polymers that, unlike the conventional bulk applications, can be applied on a nano scale, using the layer-by-layer deposition of ionic particles. The research is expected to have a significant impact on how we now can efficiently apply special textile finishes, such as FR, antimicrobial (AM), permanent-press (PP) (just to mention a few) to cotton-based textile products.
8. Bio-based research to improve status and utility of cotton in nonwovens. Use of cotton in nonwoven products until now has been minimal partly due to greige raw cotton’s lack of the desired physical and microbial cleanliness. The Agricultural Research Service (ARS) scientists at the Southern Regional Research Center (SRRC) in New Orleans, Louisiana, have met this grave challenge through a distinguished, 2-prong research approach, viz., 1) develop technology, and/or a supply source thereof, for efficiently processing greige cotton that does not have the common physical contaminants, such as plant residues, dirt, etc., and 2) develop technology to assess and eliminate any bacterial and/or microbial presence in greige cotton, which will enhance use of cotton in nonwovens. A molecular biologist, who heads the second prong of the research at SRRC, has extensively measured the greige cotton’s microbial contamination, or bio load, at various stages of the cotton processing. Based on the measurements, no hemolytic microorganisms were detected on any of the source fibers investigated in the production of hydroentangled nonwoven fabrics. The removal of trash content in the form of extraneous/foreign matter, such as leaf and stem, resulted in a 10-fold reduction in the microbial contamination levels on the greige cotton fibers. These research findings have demonstrated that the hydroentangled nonwoven fabrics made with pre-cleaned greige cotton do not have any objectionable level of microbial contaminant. This finding has had a significant scientific impact and has been awarded a significant Cooperative Research and Development Agreement (CRADA) to continue the research to demonstrate that a pre-cleaned greige cotton indeed can be beneficially utilized in a variety of medical, antimicrobial, and other hygienic cotton-based nonwoven products.
Sawhney, A.P., Allen Jr, H.C., Reynolds, M.L., Condon, B.D., Slopek, R.P., Edwards, J.V. 2011. Effect of water pressure on absorbency of hydroentangled greige cotton nonwoven fabrics. Textile Research Journal. 82(1):21-26.