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United States Department of Agriculture

Agricultural Research Service

Research Project: CHEMICAL MODIFICATIONS OF COTTON TEXTILES

Location: Cotton Chemistry and Utilization Research

2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The domestic cotton textile industry has been declining for a number of years. When cotton fabrics are crosslinked for durable press finishing, they lose a portion of their structural integrity. Furthermore, many finishing treatments release chemicals or are cost prohibitive. There is a need for new and environmentally benign treatments that will crosslink cotton without significant strength loss, and in addition, allow the fabrics to be dye-receptive, abrasion-resistant, and flame-resistant. To achieve this goal, a better understanding of the hydrogen-bonding network of cotton is necessary and the mechanisms of chemical crosslinking need to be determined. Once this is done, it will assist in the production of formaldehyde-free, second generation crosslinking agents for cotton fabrics with improved properties. Flame retardant properties are required for some 100% cotton and cotton/polyester textiles, such as carpeting, fleece and upholstery materials. These textiles are not currently approved for use in the commercial marketplace because of their inability to pass specific flammability tests. This situation is being resolved by utilizing low-cost weak-acid treatment systems, the development of new polymers, and the use of cotton composites as potential durable flame retardants for cotton. Since the early 1990's, the use of enzymes in the textile industry has increased significantly, especially in the processing of natural fibers such as cotton. A major reason for embracing the enzymatic preparation/finishing of cotton is that the use of enzymes is environmentally benign and the reactions catalyzed are very specific. In contrast, traditional chemical processing is much less specific and often results in undesirable side effects, e.g. reduction in the molecular weight of cellulose. Another major drawback of chemical processing of cotton textiles is that it often also produces problematic effluents. Despite many attractive features, enzymatic processing of cotton also has shortcomings, such as expensive processing costs and of slow reaction rates, which impede its acceptance by textile industry. This problem is being resolved by the use of low intensity, uniform, ultrasound energy (sonication) during enzymatic processing. Potential benefits of combined enzyme/sonication processing include energy and water savings, a sharp decrease of toxicity of wastewater effluents, and improved product quality.

The future use of cotton in specialty textiles will be influenced by market trends. In the area of smart and interactive textiles the projected growth rate is 36% by 2009. Subsets of that textile market, which include medical and military textiles and enzymes, will grow even more rapidly. In the areas of chronic wounds and uncontrolled blood loss dressings, a variety of new medical textile cotton products will offer improved efficacy and economic alternatives for medical and military uses. The product market for wound care is now valued at $1.74 billion, and 5 million Americans suffering from chronic open wounds require care that is estimated at $5-7 billion per year and increasing at a 10% annual rate. Cotton-based chronic wound dressings and bedsore prevention bed sheets are being developed to address unmet needs in chronic wound healing. Although, laboratory experiments have produced active chronic wound dressings that have been found to greatly alleviate this problem, industrial-scale production of these high technology products remains a major problem. More than 90% of combat deaths take place before reaching the field hospital, thus the ideal method for hemorrhage control on the battlefield would include an immediate and robust clotting response within the soldiers clothing. There are currently few cotton-based dressings that accelerate clotting appropriately for battlefield trauma. A cotton-based medical textile having blood clotting properties that can be applied to both wound dressings and uniforms would meet this need. The project specifically addresses Objective 1.1 of Goal 1 of the ARS Strategic Plan to provide science-based knowledge and technolgies to generate new or improved high-quality, value-added products and processes to expand domestic and foreign markets for agricultural commodities. This project is assigned to National Program 306, New Uses, Quality, and Marketability of Plant & Animal Products, subheading New Processes, New Uses and Value Added Biobased Products. The work is dedicated solely to expanding the use of cotton fibers.

Formaldehyde is classified as a mutagen and a probable carcinogen as well as an irritant. It also causes skin allergies. Furthermore, losses of strength and abrasion resistance in commercial durable press finishing are major problems for the cotton apparel industry. These problems directly impact cotton's competitiveness with synthetic fibers. There is a pressing need for innovative processes and new crosslinking agents to regain cotton's market share for these products. Cotton and cotton/synthetic fiber blend materials are not marketed commercially for some end-use applications because of their inability to pass specific flammability tests. This places cotton at a tremendous disadvantage compared to other less aesthetically desirable products that contain a high percentage of synthetic fibers and allow passage of mandated tests. This research is relevant to the cotton farmer, the textile industry, and the consumer of textile products. With respect to large area floor covering materials, cotton is basically excluded from a market of well over five million bales of fiber. Also, cotton is excluded from the 100 percent fleece fabric market and only participates in cotton/polyester blends where the cotton content is 50 percent or less. Effective, low cost chemical modification of cotton will allow cellulose-containing products to meet flammability standards, satisfy consumer needs, and allow cotton to garner its share of targeted markets. Processing cotton with enzymes generates wastewater effluent that is readily biodegradable and does not pose an environmental threat. Given the increasing legislative pressures by governments to decrease quantity and toxicity of textile wastewaters, even partial replacement of harsh organic/inorganic chemicals with environmentally benign combined enzyme/ultrasound processing will greatly reduce the amount of hazardous textile wastewater effluents released into environment and help textile mills conform with U.S. Environmental Protection Agency (EPA) environmental regulations.

To develop cotton with accelerated clotting properties for uncontrolled blood loss, three types of grafted and crosslinked cotton fabrics have been designed and prepared. Cotton fabrics including nonwoven, print cloth and gauze were crosslinked with naturally occurring polymers (carbohydrates and proteins) that accelerate blood clotting. The biological functionality of these added polymers has been considered in the design of these dressings. For example, chitosan (a carbohydrate) binds to platelets to initiate clotting, calcium alginate (a carbohydrate) exchanges calcium for sodium and promotes the activity of calcium with clotting factors, and collagen (a protein) has coagulant activity. Thus, development of a variety of potential approaches to wound response clothing that is on site at the time of trauma assures the likelihood of greater success for interactive clotting.


2.List by year the currently approved milestones (indicators of research progress)
FY 2006: (1) Optimize the crosslinking of cotton cellulose for the preparation of low cost and improved strength fabrics. (2) Synthesis of 13C labeled crosslinked cotton. (3) Harvest never dried bolls. Determine structural and morphological characteristics of cotton fibers as they mature. Determine the supramolecular structure and physical properties of cotton of various maturities. (4) Development of small clay particles loaded with dye molecules. (5) Develop improved synthesis for novel compounds composed of elemental silicone and phosphorous. (6) Develop techniques for clay pillaring (Pillaring is the placement of compounds or elements into the molecular layers of the clay) to impregnate clays with flame-proofing and bacteria killing agents. (7) Study the performance of specific enzymes and their possible beneficial combination under ultrasonic conditions. (8) Study the influence of auxiliary chemicals (surfactants, wetting agents, complexing agents, salts, etc.) on the combined enzyme/ultrasound processing of cotton. (9) Complete the design and testing of a pilot-scale ultrasonic reactor for continuous processing of cotton textiles by specific enzymes. (10) Prepare and test elastase colorimetric indicator on cellulose paper supports with peptide substrate. (11) Evaluate the ability of moldable, nonwoven composites manufactured from a mixture of chemically modified waste cotton and recycled petroleum-based fibers to be molded into water filtration devices. (12) Develop an industrial-scale process for phosphorylated cotton to make chronic wound dressings. (13) Prepare and test colorimetric indicators applied to wound dressings that can be used in hospitals and will indicate to nurses when it is time to change the dressing. (14) Prepare and test cotton fabrics with accelerated blood clotting properties. (15) Evaluate the properties of regenerated nanocomposite fiber (nanocomposite is a particle or structure that measures 100 nanometers or less). (16) Scale-up production of clay-cotton composite materials. (17) Evaluate and optimize the grafting efficiency of light sensitized textiles.

FY 2007: (18) Evaluate solid-state Nuclear Magnetic Resonance (NMR) studies of labeled crosslinked cotton. (19) Construct woven and nonwoven textiles from nanocomposite fabrics. (20) Select and develop hemostatic fabrics with good commercialization potential. (21) Develop technical specifications, order, install and test the new textile processing equipment (2-Roll Laboratory Padder HVC, Laboratory Drying, Condensation and Fixation Apparatus KTF-500, Laboratory Overflow Jet Dyeing Apparatus JFO and Pad-Steam Range PSA-HTF) in order to re-establish the Textile Pilot Plant that was destroyed by Hurricane Katrina. (22) Design and manufacture two different ultrasound untis (planar and coaxial) for controlled combined high energy treatment called sonication of textile samples and enzyme processing solution. These units will be also instrumental in our new study of the enhancement of enzymatic hydrolysis of plant cellulose in bio-fuel applications by ultrasound. (23) Study the performance of specific enzymes on cotton and plant cellulose and their possible synergistic combinations under sonication conditions. (24) Improve the sensitivity of elastase colorimetric indicator on cotton using paper as a model. (25) Apply and test the application of novel silicon/phosphorus containing compounds to chemcially mofidied cotton.

FY 2008: (26) Develop technique for postively charged pre-treatment of samples of waste cotton that will be well-matched with "pillared" and "loaded" clay-based finishes. (27) Study the influence of auxiliary agents (cavitation bubbles promoters, degassing agents and wetting agents) on the combined enzyme/ultrasound processing of cotton and plant cellullose (bio-fuel applications). (28) Determine cottn crosslinking mechanism based on Nuclear Magnetic Resonance (NMR) studies. (29) Study the influence of auxiliary chemicals (surfactants, wetting agents, complexing agents, salts, etc.) on the combined enzyme/ultrasound processing of cotton. (30) Evaluate flammability of woven and nonwoven textiles. (31) Complete manufacturing trials of the cotton-based chronic wound dressing and provide product prototype for clinical trials. (32) Addfress manufacturing trials of the cotton-based chronic wound dressing for initial distribution.

FY 2009: (33) Complete the design and testing of a pilot-scale sonication reactor for continuous enzymatic bio-procjessing of cotton textiles. (34) Assess batericidal properties of samples of waste cotton pillared and loaded clay-based finishes.


4a.List the single most significant research accomplishment during FY 2006.
COTTON-BASED CHRONIC WOUND DRESSINGS: An aspect of research and development targets meeting major unmet needs in nursing home, bedridden and burn patients with non-healing and burn wounds. This is done by developing new cotton-based wound dressings that will selectively interact with either chronic wounds or burn wounds. This year we developed a continuous pilot-scale process for producing phosphorylated cotton (cotton modified by adding phosphate groups) gauze. Following manufacturing trials to commercialize the cotton-based dressing toxicology studies were completed on the dressing, and application to the Food & Drug Administration (FDA) for approval to distribute the dressing was launched. In July 2006, the FDA approved the cotton chronic wound dressing for use in patients. The impact of this work will benefit the consumer who has need of improved wound dressings, and it will benefit the cotton farmer and American textile industry by increasing the volume of value-added cotton product sales in the United States.


4b.List other significant research accomplishment(s), if any.
FLAME RETARDANT AGENTS: In an attempt to produce new and effective flame retardant agents, silicon and phosphorous have been combined to produce several new compounds. These silanes either as is or polymerized could potentially be applied directly to cotton.

REGENERATED CELLULOSE COMPOSITE FIBERS HAVE BEEN PRODUCED BY SOLUTION SPINNING TECHNIQUES. The composite fibers were processed into nonwoven substrates by small-scale paper production techniques. The fibers used to produce these materials show enhanced fire-resistant and self-extinguishing properties and are being scaled up to produce nonwoven products in collaboration with the University of Tennessee in Knoxville. ENHANCEMENT OF ENZYMATIC PROCESSING: New enzymatic preparation and finishing techniques of various cotton textiles were investigated and tested. This novel environmentally friendly process utilizes a combination of ultrasound energy and highly specific enzymes. Industrial implementation of this new textile processing should greatly reduce the amount and toxicity of wastewater effluents, energy consumption, and overall processing costs.


4c.List significant activities that support special target populations.
The development of smart cotton-based wound dressings that selectively extract destructive enzymes from the chronic wound and the bed sheets will target nursing home and hospital patient populations where patients are elderly, spinal impaired, diabetic or otherwise bedridden. The flexible and absorbent wound dressing made from cotton targets these same nursing home and patient populations in addition to burn patients. Other wound dressings and sensors target uniforms of military personnel.

Five compounds (based on inexpensive and easily reactive starting materials) were prepared and their reactivity to UV light initiation and atmospheric conditions were studied. Such derivatives are members of a promising class of compounds for textile finishes that can be prepared under inexpensive and environmentally friendly conditions, such as exposure to air and ultraviolet light.

New enzymatic preparation and finishing techniques for cotton textiles were developed employing the combined pectinase/ultrasound and cellulase/ultrasound processing of variety of cotton fabrics. These environmentally friendly techniques utilize a combination of low energy, uniform sonication and highly specific enzymes. Widespread implementation of this new textile processing should greatly reduce the amount of wastewater effluents and overall processing costs.


4d.Progress report.
One subordinate project was established through a Trust Agreement with ARS and DeRoyal Industries, Inc. and one subordinate project was established through a Non-Funded Cooperative Agreement with ARS and Tissue Technologies. Patents licensed to DeRoyal Industries, Inc. and Tissue Technologies will permit the commercialization of the SRRC chronic wound dressing material during the next several years. During FY 2005, a manufacturing process for the production of a cotton chronic wound dressing was developed. The process was implemented at the proposed manufacturing site of the dressing in an operating textile mill. The development of a process for manufacturing the wound dressing involved on-site modifications to the manufacturing equipment, follow-up assays of the wound dressing and several trial runs. A wound dressing product comparable in efficacy to the laboratory scale-produced dressing was made from the manufacturing trials and subsequently passed toxicology studies, and was approved by the FDA for use in patients.


5.Describe the major accomplishments to date and their predicted or actual impact.
Nearly a dozen varieties of naturally colored cottons, which show a natural enhanced flame retardance, have been processed into nonwoven material. These cottons were tested to identify the species that showed the greatest flame retarding ability. The inherent flame retardance of these cottons was correlated with color intensity of the samples, and it was shown that the color and naturally occurring compounds responsible for the flame retardant properties could be isolated. These naturally occurring materials have been identified as polycondensed tannins. The cotton that was isolated as having the best flame-retardant characteristics was planted and more of this natural product will be extracted from the fibers to formulate a finish for flame retardancy to be used on white cottons. Additionally, commercially available tannins have been obtained and used in small-scale studies to determine flame retardancy of these materials at various stages of condensation.

Print cloth was treated with a chemical agent (polymer) to make it sensitive to ultraviolet light and allow a finish to be chemically bonded with the cloth. The grafting onto the textile surface has been confirmed by instrumental techniques. Standard strength tests on the print cloth indicate that a moderate loss in tear strength (12%) results from the loss of molecular weight because of the light activation, but this loss in strength is overcome by the grafting/finishing reaction because of the entanglement of the polymer chains on the surface of the cloth. The amount of agent bound to the surface was studied to determine the viability with common compounds and was found to be acceptable.

Enhanced Enzymatic Processing: Compound treatment of cotton and other cellulosic fibers with enzymes is a nontoxic, environmentally benign process that is gaining greater recognition for numerous textile-processing applications, such as desizing, souring, polishing, bleaching, stoning, and garment laundering. But in addition to numerous advantages, there are several important shortcomings in the enzymatic treatment of cotton fibers, such as more expensive processing costs and slow reaction rates and, occasionally, excessive fiber damage. Our research demonstrated that enzyme activity could be significantly enhanced by the introduction of a low energy, highly uniform ultrasonic energy field. The combined enzyme/ultrasound processing of cotton and other cellulosic fibers offers significant advantages, such as less consumption of expensive enzymes, shorter processing time, and significant decrease in the amount and toxicity of textile effluents. The predicted impact of this technology is that combining an enzymatic processing with low energy, uniform sonication could significantly enhance the performance of the variety of industrial enzymes, thus making this new, environmentally benign processing of cotton more suitable for widespread implementation.

Cotton-based Chronic Wound Dressings: ARS scientists' findings show that the activity of the enzyme, elastase, in chronic wound fluid can be lowered with modified cotton gauze. This further suggests that our modified gauze may be better suited for application to chronic wounds over standard cotton gauze in use now. This preference is scientifically based on rational design of an enzyme active site uptake affinity of harmful enzymes such as elastase. In addition burn wound dressing materials were invented to promote moist healing and retain elasticity around joints while providing water transmissibility. Blood clotting bandages were made that accelerate the rate of clotting response on the fabric, and stop the flow of blood in a bleeding wound more rapidly than regular bandages. The impact of these technologies is significant for value-added cotton and in aiding the improvement of cotton gauze dressings for chronic and burn wounds. Impact will be realized both as an agricultural commodity and on a major health care problem.

Clearly all of the above accomplishments relate to National Program 306, New Uses, Quality, and Marketability of Plant & Animal Products, subheading New Processes, New Uses and Value Added Biobased Products.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Bandage gets FDA approval: Richmond company creates dressing to aid in healing wounds, By Jeffrey Kelley,Times-Dispatch Staff Writer, Richmond Times Dispatch, Friday, July 14, 2006.


Last Modified: 4/18/2014
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