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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Cotton Chemistry and Utilization Research » Research » Research Project #428080

Research Project: Cotton-based Nonwovens

Location: Cotton Chemistry and Utilization Research

2019 Annual Report

Objectives
Objective 1: Enable, from a technological standpoint, new commercial products and market applications for cotton containing nonwoven materials. Objective 2: In collaboration with the ARS Cotton Fiber Bioscience Lab, enable a new commercial variety of white cotton exhibiting improved flame retardancy. Objective 3: Use nanotechnology to enable new commercial cotton products.

Approach
Through fiber selection and blending combined with modification of nonwoven bonding processes, specialty and commodity cotton-based nonwoven fabrics can be produced which are suitable for new disposable or semi-durable applications. The approaches primarily include the following. Procure the required raw materials from commercial sources and using the in-house, commercial-grade production equipment and procedures, sufficient quantities will be prepared of the required fibrous batts for the downstream needlepunch and hydroentanglement of the fibers into nonwoven fabrics. The research products will be comprehensively tested for the required pertinent information to closely assess their values for the targeted end-use products. Based on the process and fabric evaluations, the most promising research fabrics/products will be selected for duplicate confirmation before embarking on their pilot operations. Offer the selected fabric(s) and explore industrial partners for mutual cooperation to take the research product to industrial trials. The development of new cotton fibers with unique properties, and novel chemical applications for cotton-based nonwovens will be explored. Cotton fibers with specific inherent properties such as natural increased flame resistance (FR) observed in brown cotton fibers will reduce the need for external applications of chemical additives to achieve the desired functionality. The scientific approach will attempt introgression of improved FR from brown cotton fibers into fibers of conventional white cotton varieties through traditional breeding approaches while attempting to identify and characterize the compound(s) responsible for the increased FR. The molecular mechanisms of FR in brown cotton fibers are unknown and a comparative chemical analysis between selected brown and white fiber cotton varieties has the potential to identify novel biomolecules or other molecular components that can be adopted as naturally occurring additive chemistries to existing nonwoven textiles. The production of durable antimicrobial cotton products using nanotechnology will be explored. Since silver (AG) nanoparticles (NPs) formed inside the cotton fiber are expected to be stable and to release antimicrobial ions in a controlled manner for the protection against harmful microorganisms, Ag-cotton nanocomposite fiber can find new technical nonwoven applications, such as wound dressings and biomedical devices. To verify the continuous and long-lasting antimicrobial activity of Ag NPs caged inside cotton fiber, the kinetic study on the Ag ion release in aqueous environment will be examined, and the variation of the antimicrobial properties of the resulting cotton will be monitored. This research will also focus on the incorporation of other multifunctional NPs into cotton fiber. The production of nano-sized metal or transition metal particles inside cotton fiber would provide the increased flame retardant performance as well as durability. As one of non-halogenated flame retardant solutions, this research will focus on transition metal elements that have known flame retardant effects and the synthetic methods of their NPs.

Progress Report
Progress was made on all three objectives, all of which fall under National Program 306, Component 2 Product Quality and New Uses, Non-food. Progress on this project focuses on developing knowledge and enabling commercially-viable technologies to (1) measure and maintain/enhance post-harvest product quality, (2) harvest and process agricultural materials, and (3) create new value-added products. Under Objective 1, ARS researchers developed an industry scalable protocol for producing 100% cotton-based disposable wipes that had a positive surface charge. Cotton fibers naturally have a negative surface charge that makes them incompatible with the most commonly used hard surface disinfectants known as quaternary ammonium compounds (quats). By changing the cotton surface to a positive charge, the positive quats are now repelled from the cotton surface and reach and effectively disinfect the target surface. Preliminary testing indicated that the new cotton wipes could successfully clean and disinfect a hard surface contaminated with potentially pathogenic bacteria. To promote the transfer of this technology to commercial products, ARS researchers conducted a quantitative research survey that analyzed the attitudes and usage of a target group consisting of facilities managers and managers who make product decisions for cleaning materials in hospitality, healthcare, and building service markets. The overall response was largely positive in the willingness to utilize this cotton-based disinfecting technology as a replacement for, or in addition to currently used products. More than three quarters of those surveyed indicated extreme interest in purchasing a new product with this technology. This quantitative research further supports the development of a quat-compatible cotton-based disinfecting wipe and provides value data to approach nonwovens stakeholders interested in commercializing a cotton-based disinfecting wipe. Also, under Objective 1, significant progress was made developing prototypes of disposable spatial insect repellant patches that can be affixed to clothing and avoid direct skin contact with chemicals. Currently, such products are composed primarily of synthetic petroleum-based fabrics that are not environmentally friendly or readily biodegradable. Natural biobased spatial insect repellants are currently being evaluated in comparison to the commonly used synthetic topical insecticide permethrin through mosquito landing experiments in collaboration with the Mosquito and Fly Research Unit in Gainesville, Florida, which is under USDA National Program 104 – Veterinary, Medical, and Urban Entomology. Under Objectives 1 and 2, ARS researchers in New Orleans, Louisiana, identified and selected cotton lines with broad variances in fiber quality traits that contribute to the value of the cotton fibers. Nonwoven fabrics of light and heavy weight were produced from the fibers and subjected to standardized strength and moisture management testing. The strength properties of light weight nonwovens fabrics were directly affected by fiber quality measurements. Longer and finer fibers produced fabrics with 70% higher strength compared to fabrics produced from shorter, coarser fibers. Both heavy and light weight fabrics had a direct positive relationship between liquid moisture handling and fiber coarseness, with coarser fibers being better suited for nonwoven applications designed to effectively transport liquid away from the skin surface. Examples of use include apparel to wick sweat from the skin surface and in hygiene applications such as feminine pads, diapers, and incontinence. This research has the potential to provide guidance for the use of U.S. cotton fibers in alternative markets such as domestic nonwovens production, particularly for fibers with reduced value due to inferior quality classifications. The cotton fibers in this study that were very coarse were from selected lines that were also extremely high yielding, a desirable trait for agricultural commodities. This presents the opportunity for developing high yield cotton varieties cultivated specifically for nonwoven textile production. Under Objective 2, significant progress was made developing advanced cotton lines that have fibers with enhanced flame retardancy (FR). ARS researchers previously identified a cotton variety that can be used to make nonwoven fabrics that are self-extinguishing. Further analyses identified additional cotton lines that exhibit self-extinguishing behavior. Conventional cotton lines produced nonwoven fabrics that caught fire and were consumed by flame. Cotton fiber blends were made with synthetic FR fibers called Nomex that are commonly used in woven FR apparel for military and first responder applications. Cotton fiber blends with a Nomex concentration between 20% and 30% revealed dramatic differences between selected FR cotton and normal cotton fibers. The nonwoven fabric produced from a normal cotton/Nomex blend still ignited and burned. Fabrics composed of FR cotton/Nomex blends in the same ratio did not ignite and passed flammability tests. Currently, FR apparel used by the military is composed of a blend of FR rayon, Nomex, and nylon. This research presents opportunities for developing a cotton variety to produce inherently FR cotton fibers and fabrics as a more cost effective alternative to FR rayon. All rayon raw material sourcing and manufacturing occurs outside of North American so this research also supports The Berry Amendment that requires defense procurement to come from domestic sources. Under Objective 2, significant progress was made in developing DNA markers that are associated with cotton fiber quality traits. ARS-Cotton Chemistry and Utilization researchers in collaboration with the Cotton Fiber Bioscience Research Unit conducted genome sequencing and identified 473,517 DNA markers that are segregating in a population of 550 inbred cotton lines. These markers, along with traditional evaluations of cotton fiber properties and observations of novel end-use cotton fiber and textile characteristics, identified seven highly significant genetic regions that contribute to the length, strength and fineness of cotton fibers, and also the inherent FR fiber trait previously mentioned. Additionally, we have begun exploring the effect of candidate genes that affect fiber elongation, a measure of how far a fiber can stretch before breaking. Preliminary tests on nonwoven fabrics produced form cotton fibers with a high elongation revealed these fabrics had higher stretch when a constant force was applied. This characteristic has the potential to improve nonwoven fabric properties such as drape, hand, and elasticity. The genes that were found to influence fiber fineness may affect the absorbency and fluid handling of non-woven textiles generated from these novel cotton lines. Indeed, the self-extinguishing characteristic of the novel white cotton lines is not present in any known cotton cultivar, and was presumably facilitated by a novel combination of numerous, diverse, beneficial and synergistic forms of genes that interact in novel ways in the inbred cotton populations. Under Objective 3, significant progress was made toward the goal of developing silver nanoparticle (Ag NP)-enhanced antibacterial cotton nonwoven materials based on a new analytical method to quantify Ag NPs. Due to their antibacterial, antifungal, and partially antiviral properties, Ag NPs are widely employed in the production of odor-neutralizing and anti-infective textile products. However, these commercial products leach out a significant amount of Ag NPs during use and washing, indicating a lack of durability. ARS researchers successfully developed a new surface-enhanced Raman spectroscopy technique to identify Ag NPs and measure their concentration in washing liquid. The analysis using this new method revealed that Ag NPs in the Ag-cotton system are highly durable against consecutive launderings. The amount of Ag NPs in a detergent solution for the internally dispersed Ag-cotton was about 80 times smaller than the amount for the externally dispersed (i.e., coated) Ag-cotton after 30 home launderings. The comparison of the concentrations of Ag NPs between water and detergent liquid after washing showed that the internally dispersed Ag-cotton system developed by ARS researchers was more resistant to detergent than the commercial externally dispersed Ag-cotton. Under Objective 3, ARS researchers developed a new method to identify the triple transition (glass transition-dehydration-crystallization) of cotton fiber. The dependence pattern of activation energy for the thermal decomposition of cellulose on preheating temperature determined the three consecutive thermal transitional temperatures for glass transition, dehydration, and crystallization. This work resolved the conflicting views on unordered (amorphous) cellulose chains of cotton fiber due to the difficulty in detecting their conformational change. In line with uncovering the structure of amorphous cotton cellulose, ball milling was used to obtain almost pure amorphous cellulose and revealed its morphology, molecular-level interactions, and structural domains using 13 analytical techniques. ARS researchers developed a solvent system to isolate cellulose nanocrystals from cotton fiber. The structure of the obtained nanocrystals was verified by X-ray diffraction, field emission scanning electron and atomic force microscopies. Using these nanocrystals, ARS researchers developed a colorimetric biosensor for detection of human neutrophil elastase, a serine protease central to the pathology in a broad range of diseases. Its detection efficiency was greater than that of an analogous sensor from wood cellulose due to the uniform crystalline structure.

Accomplishments
1. A positively charged (cationic) 100% cotton disposable disinfecting wipe. An industry scalable protocol was developed by ARS scientists in New Orleans, Louisiana, for producing 100% cotton-based disposable wipes that have a positive surface charge. This protocol could be integrated into existing industry equipment for scouring and bleaching cotton fibers which could then be converted to nonwoven wipes on standard production equipment. Cotton fibers naturally have a negative surface charge that makes them incompatible with the most commonly used hard surface disinfectants known as quaternary ammonium compounds (quats). Quats are positively charged, and since opposites attract, they stick to the negative surface of cotton fibers which does not allow them to reach and disinfect a surface. By changing the cotton surface to a positive charge, the positive quats are now repelled from the cotton surface and reach and effectively disinfect the target surface. Preliminary testing indicated the positively charged cotton wipes can be used with quats to successfully clean and disinfect hard surfaces contaminated with either Staphylococcus aureus or Pseudomonas aeruginosa.

2. Washable antibacterial cotton wipes. Based on the utilization of the unique structure and chemistry of cotton fiber, various methods have been developed by ARS scientists in New Orleans, Louisiana, to embed antibacterial silver nanoparticles (Ag NPs) into cotton fiber (Ag NP-cotton fiber). According to recent studies, commercially available textile products containing Ag NPs leach out a significant amount of Ag NPs, i.e., 24-87% of the total Ag in the textiles were washed off in detergent solutions during five machine washes. The developed Ag NP-cotton fiber retained a majority of Ag NPs (above 70%) after 50 machine washes, exhibiting excellent washing durability. Cotton nonwoven fabrics containing Ag NP-cotton fiber were fabricated in the in-house pilot plant using industrial equipment. The Ag NP-cotton fiber could be readily blended in the existing industry carding process. The obtained hydroentangled cotton wipes are soft but exert powerful antibacterial functions to kill 99.9% of the most common bacteria causing infections. The methods developed for permanent antibacterial cotton have led to two approved invention disclosures: 1)Raw white and brown cotton fibers self-generating silver nanoparticles for wash-durable antibacterial textiles and 2) Fast, reproducible, and heat-free internal synthesis of silver nanoparticles in cotton fiber for wash-durable antibacterial textiles. This technology transfer is supported by the ARS Innovation Fund.

3. A simple but accurate method to identify the glass transition of cotton fiber. Cotton fiber has two domains consisting of ordered (crystalline) and unordered (amorphous) cellulose chains. While the information on the crystalline structure is extensive and highly developed, the literature on the amorphous structure is incomplete and contradictory. The glass transition, the transition from rubbery to brittle "glassy" state in the amorphous domain, is important in advantageously processing cotton materials. The developed method using the dependence pattern of activation energy for thermal decomposition of cellulose on preheating temperature was sensitive enough to detect the glass transition, which could not be identified by other techniques. This work by ARS scientists in New Orleans, Louisiana, resolved why the glass transition temperatures of cellulosic materials in the literature are so varied and high, that is, currently available techniques are misled by the dehydration of amorphous cellulose, which occurs at temperatures slightly higher than the actual glass transition temperature. This novel technique was invited for invention disclosure. The outcomes would contribute to the modification of cotton fiber for improved mechanical and thermal properties and provide new insights into the conformation of cellulose chains for hosting nanomaterials.

U.S. DEPARTMENT OF AGRICULTURE

Cotton Chemistry and Utilization Research: New Orleans, LA