1a. Objectives (from AD-416)
Objective 1 - Develop chemistries and treatments that enable new cotton-based products for biomedical and specialty applications. Objective 2 - Develop enzyme-based technologies that enable new cotton-based products for decontamination applications. Objective 3 - Develop new finishing chemistries and innovative treatment processes that enable new cotton-based products with flame retardancy and moisture control. Objective 4 - Develop environmentally friendly cotton, dyeing and finishing processes based on the combination of sonication and enzymatic technologies.
1b. Approach (from AD-416)
The U.S. cotton industry continues to face supply and demand concerns. Since cotton is used in manufactured products, the industry has been challenged by the downsizing of manufacturing facilities that traditionally provide a major underpinning to domestic cotton consumption. Thus, with the goal of giving U.S. cotton utilization a competitive edge, research emphasis will be placed in cotton fiber science and product development where consumer and industrial needs are unmet and show promise. Some of the areas of consumer need for cotton products and process potential are: specialty nonwoven pads and wipes medical/hygiene, apparel/home furnishings, and enzymatic bio-processing. The targeted research in the areas of synthetic chemistry, enzymatic, bio-processing, flame retardant chemistry, and analytical cotton fiber science will be undertaken by the collaborative efforts of the Cotton Chemistry Utilization Unit to yield new cotton products. Collaboration and synergy with the research unit’s cotton nonwoven project in the areas of value-added cotton materials, enzymes, processing, and environmental sustainability make the likelihood of success high. Products that are envisioned to arise from this research include medical, hygiene, and hospital materials, broad spectrum anti-microbial and decontamination wipes, durable low-cost flame retardant apparel and home furnishings, and ultrasonic approaches for smooth finishing of cotton textiles. This proposed research also takes into account preserving the environment and economical cost. Research emphasis will be placed on developing approaches to enable a comprehensive understanding of the relation of structure to function on modified cotton for a broad range of potential uses.
3. Progress Report
We have developed new cotton-based products, finishes, and materials with superior medical, health and safety properties, and novel, environmentally friendly techniques for combined enzyme/ultrasound bio-processing of cotton textiles and bio-conversion of agricultural waste biomass into bio-fuels. The combined effect is to increase the competitiveness of cotton and cellulose-based feed stocks against synthetic fibers. Commodity utilization research on new consumer cotton products has included the development of new flame retardant cotton finishes for apparel and durable goods, functional dressings including hemorrhage control, antimicrobial and decontamination wipes and nonwoven absorbent incontinence: 1) novel flame retardant compounds combining phosphorous and nitrogen, were found to function optimally as cotton finishes on cotton print cloth, twill and fleece fabrics, offering a more efficient and low cost ability to retard flame propagation while meeting government mandates; 2) the clotting properties of cotton-based dressings were characterized elucidating their mechanism of action in the coagulation cascade, which advances battlefield wound dressing technology and efficacy; 3) the attachment of active antimicrobial and decontamination enzymes to cotton promises a novel route to custom germ-killing and decontamination wipes; 4) the fiber surface properties of cotton nonwovens were characterized for their potential to be used in commercial incontinence products; and 5) the introduction of a uniform ultrasound field during enzymatic cotton textile bio-processing and bio-conversion of switchgrass (a cellulosic agricultural product) resulted in a significant acceleration of both bio-finishing and the conversion of the switchgrass into bio-fuels.
1. Biomedical cotton-based materials. ARS scientists at the Southern Regional Research Center (SRRC), New Orleans, Louisiana are bringing many positive attributes to cotton that are of value for biomedical materials including absorbance, softness, comfort, non-irritating, hypo-allergenic and breathability. Thus, cotton is targeted to unmet needs in the medical textile arena including urinary incontinence, pressure ulcer treatment and management, hemorrhage control, and antimicrobial and decontamination wipes. The current analysis and development of improved cotton properties with functionally absorbent and fiber surface characteristics that accelerate clotting, improve water transport and absorption, and have broad spectrum antimicrobial activity have demonstrated promise toward product prototypes. Increasing positive fiber surface charge was shown to yield accelerated clotting. The design of cotton nonwovens in urinary incontinence control gives hypo-allergenic properties, and enhances comfort with high absorbance capacity. The development of incontinence and pressure ulcer prevention materials will target the adult incontinence population and nursing home and hospital patient populations where patients are bed ridden, elderly, spinal cord paralysis, or diabetic. The flexible and absorbent wound dressing made from cotton targets these same nursing home and patient populations in addition to burn patients. Antimicrobial and decontamination wipes target both travelers and pesticide and hazardous chemical workers. The development of battlefield dressing hemorrhage control agents is in high demand now by the U.S. Armed Forces, and a highly effective deployed product could increase the number of lives saved. Flame retardant treatment will target fire fighter uniforms, children’s sleep wear, and home furnishings.
2. Flame retardant cotton products. ARS scientists at Southern Regional Research Center (SRRC), New Orleans, Louisiana are currently addressing a need for durable flame resistant cotton fabrics for apparel and household items. New organo-phosphorous and nitrogen-based flame retardant fabrics were developed. A combined phosphorous and nitrogen cotton fabric finish demonstrated excellent performance in the American Society of Testing and Materials vertical flame test and other flame retardant signature tests. This new flame retardant system offers advantages including char formation from phosphorous, incombustible gas without toxic smoke from nitrogen and the synergism that both of these properties provides to enhance ability to retard flame propagation. In addition the use of supercritical carbon dioxide, which will accommodate a broader range of finishing chemistries, as an alternative solvent for application of chemical treatments to cotton is of commercial interest with the recent advent of large scale supercritical carbon dioxide reactors.
3. Bio-processing of cotton textiles and agricultural waste biomass conversion. In general, an enzymatic bio-finishing of cotton generates less toxic and readily biodegradable wastewater effluents. The ever-increasing legislative pressures to reduce the quantity/toxicity of industrial wastewaters will ensure greater acceptance of enzymatic bio-processing in the future. However, enzymatic bio-processing of cotton has several critical shortcomings that impede its wide acceptance by industries: expensive processing costs and slow reaction rates. ARS scientists at the Southern Regional Research Center (SRRC) at New Orleans, Louisiana, found that introduction of ultrasonic energy in the reaction chamber during enzymatic bio-finishing of cotton improved enzymes efficiency up to 25-35%. This improved efficiency thru bio-processing improves the potential to utilize enzymatic bio-finishing as a more sustainable and renewable alternative. The enhancement of enzymatic bio-conversion of plant biomass into sugars/ethanol by ultrasound could significantly advance domestically produced bio-fuels. One of the most critical stages of conversion of plant biomass into bio-fuels employs hydrolysis reactions between highly specific enzymes and matching cellulose substrate to produce soluble sugars converted into bio-fuels. Low level, uniform ultrasound field applied to the enzymatic hydrolysis of switchgrass cellulose demonstrated improved hydrolysis of pretreated plant cellulose into sugars by up to 256% on average.
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