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 third 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 Cooperative Research and Development Agreement(s).
1. Bleaching and possibly dyeing of cotton nonwoven fabrics without the traditional, costly and eco-sensitive chemical scouring process. Greige raw cotton naturally has certain waxes that must be removed, using a rather costly and environmentally-sensitive chemical process called scouring, in the production of almost all cotton-based textile fabrics. Agriculture Research Service (ARS) scientists at the 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 considerably removing these waxes. This significant research milestone eventually led to a hypothesis in that a hydroentangled greige (raw) cotton nonwoven fabric could be bleached and possibly dyed without the traditional scouring process. The research investigations directed toward proving the hypothesis have indeed shown that an appropriately hydroentangled greige cotton nonwoven fabric can be bleached satisfactorily without the scouring process. This research outcome will contribute to saving money, energy, chemicals and above all, the earth’s ecology, which ultimately will expand use of cotton in nonwovens. A manuscript has been prepared for publication in a peer-reviewed textile research journal.
2. Utilization of cotton gin motes and textile processing comber noils in nonwovens for incontinence and related products. Production of cotton lint fiber in ginning process produces a by-product called gin motes and production of combed yarns and fabrics from cotton lint produces a by-product known as comber noils. Both of these cotton co-products in their 'greige' (raw/non-bleached) stage are generally unsuitable for traditional textile fabrics and, therefore, sell for far less than the cotton lint. Although these (nearly waste) materials in their bleached stage have long been used in production of value-added nonwoven products for medical and hygienic end-use products, the greige gin motes and comber noils have had only limited uses as bio mass and 'filling' materials (for certain household and industrial products). However, the United States Department of Agriculture (USDA), Agricultural Research Service research in New Orleans, Louisiana, has found that these less expensive, greige materials, when cleaned of their foreign matter and, preferably, in blend with other fibers, can be beneficially utilized as a cover stock (a component of value-added continence products), since these greige cotton by-products have been found to be more absorbent (moisture uptake) than their bleached counterparts. The research has led to preparation of a peer-reviewed manuscript that is expected to be published soon.
3. Deploying a series of multiple hydro impacts at different water pressures. An investigation was conducted by Agricultural Research Service (ARS) scientists to determine the effect of cumulative hydro energy consumption on properties of the greige cotton nonwoven fabric produced on a commercial-grade hydroentangling nonwovens system. The results have shown that, depending on the end product, a series of hydro impacts at a relatively lower water pressure may reduce energy consumption in production of certain nonwoven fabrics. A manuscript has been prepared for publication in a refereed journal.
4. Development of quat-loaded greige cotton decontaminating industrial wipe. Most decontaminating and/or antimicrobial wipes available in the market today use synthetic and other manufactured fibers, although some pulp is also used. Use of natural cotton fiber is minimal in these end-use products, 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. Therefore, the underlying research issue was how to optimally reduce adsorption of the quat by greige cotton, while improving ease of release and effectiveness of the quat onto a contaminated surface. The research has shown that greige cotton’s pectin content and to a lesser extent its wax content actually played significant roles in the adsorption of decontaminating agents by the nonwovens made with greige (non-bleached) cotton. The research has also revealed that the addition of alcohol, electrolytes, and a nonionic surfactant to the decontaminating solution greatly reduces, or even completely eliminates, adsorption of the decontaminating agent by both the greige and bleached cotton nonwovens. The research is believed to have led to a scale-up evaluation of the United States Department of Agriculture (USDA), Agricultural Research Service developmental decontaminating wipes by outside commercial entities. The research results have been published in the Textile Research Journal, a refereed journal.
5. Effect of the water jet intensity in a hydroentanglement system on properties of the nonwoven fabrics made with greige cotton lint. Hydroentanglement is a modern system of efficiently producing nonwoven fabric structures. Although this system has been in vogue for decades, it mostly has been used in making nonwoven structures using synthetic and other manufactured fibers. The system has been rarely used in manufacturing especially greige cotton goods, although pulp has been extensively used to make papers by the system. The water jet intensity, which essentially depends on the orifice size of the high-water-pressure-strip and the magnitude of the high water pressure deployed in the system, has been found to considerably affect removal of greige cotton’s natural waxes. This finding, in turn, has led to development of producing absorbent nonwoven fabrics made with non-absorbent greige cotton, thus at least reducing, if not completely eliminating, the traditional burden of cotton scouring process that involves costly chemicals, time and energy and, consequently, adversely impacts the environment.
6. Novel chemical concepts to make cotton textiles flame-suppressant, antimicrobial and/or decontaminating. Making cotton textiles of certain desired functionalities (e.g., flame/fire retardant (FR), etc.) have been serious challenges for many years. Diligent research approaches by several Agriculture Research Service (ARS) scientists and especially postdoctoral fellows have resulted in some interesting new chemicals and their reactions with cotton. However, the durability of these newly discovered formulations is still a challenge to overcome. The research has attracted attention of industrial entities, who are interested in certain function-specific cotton fabrics for both woven and nonwoven goods. A few manuscripts on these new research developments have been published.
7. Cotton-based nanotechnology. Nanotechnology is a rapidly progressing tool for advanced research, development and even production of improved products from almost all the basic materials, including cotton, our planet earth provides. Agriculture Research Service (ARS) scientists at Southern Regional Research Center (SRRC) 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 develop unique methods of efficiently applying special textile finishes, such as flame retardant (FR) and antimicrobial (AM) (just to mention a few) to cotton-based textile products.
8. Bio-based research to further improve status and utility of cotton in nonwovens. Use of cotton in quality nonwoven products has been minimal partly due to lack of the desired physical and microbial cleanliness of classical greige raw cotton. The Agricultural Research Service (ARS) scientists at Southern Regional Research Center (SRRC) are obliged to meet this rather difficult and perhaps politically complex challenge through a distinct, 3-prong research approach, viz., 1) specifically for the nonwovens industry, develop ARS technology for efficiently processing and cleaning the classical greige cotton at the gins; 2) identify, certify and support a reliable commercial supply source of pre-cleaned greige cotton that is free of the common physical contaminants such as the cotton plant and seed residues, dirt and trash, etc. of classical greige cotton; and 3) develop technology to assess and eliminate any bacterial and/or microbial presence in greige cotton. This research approach, when successfully executed, will considerably enhance the use of cotton in nonwovens. The SRRC scientists so far have identified an excellent commercial source of cleaned greige cotton that repeatedly has been tested and later processed into acceptable nonwoven fabrics. This commercial greige cotton’s microbial contamination, or bio load, at various stages of its processing was also measured and no hemolytic microorganisms were detected. The research has demonstrated that the pre-cleaned greige cotton indeed can be successfully utilized to produce a variety of medical, antimicrobial, and other (non-sterile) hygienic nonwoven products. The research results have been assembled into a manuscript (of 12 authors, however without the Lead Scientist) for broad dissemination of the research outcome.
Sawhney, A.P., Reynolds, M.L., Allen Jr, H.C., Slopek, R.P., Condon, B.D. 2013. Effects of greige cotton lint properties on hydroentangled nonwoven fabrics. Textile Research Journal. 83(1):3-12.