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.
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.
Agricultural Research Service (ARS), Cotton Chemistry and Utilization (CCU) research scientists determined the progressive and cumulative effects of multiple hydroentangling impacts at three different water pressures on properties of the resulting nonwoven fabrics made with commercially cleaned raw cotton fibers. Analysis of these parameters contributed to addressing industrial concerns that so far have severely limited the use of cotton in modern nonwovens. These results showed that, depending on the required or preferred fabric properties, the stated hydroentangling process parameters can be considerably manipulated to achieve efficient hydroentanglement and improved energy efficiency. ARS, CCU research scientists conducted research to explore the utility of cotton and cotton blends in hydroentangled nonwoven fabrics. The study was conducted to assess the effects of blending, in three different blend ratios, of pre-cleaned raw cotton fibers with man-made fibers including polyester, polypropylene, Tencel, viscose rayon, and bleached cotton, on properties of the of nonwoven fabrics made by using a pilot scale hydroentanglement system. A total of twenty one different fabrics were made using the selected fibers, blend ratios, and processing metrics. Each fabric was made in three replicates to ensure reproducibility and the statistical validity of the test data. The study demonstrated the blends of cleaned raw cotton with manmade fibers were efficiently processed on the hydroentanglement system and the resulting nonwoven fabrics exhibited satisfactory or improved properties of strength, whiteness, and absorbency compared to 100% cotton-based nonwoven fabric. The study has shown that the pre-cleaned cotton can be efficiently processed and converted into viable nonwoven fabrics of integrity and satisfactory properties that would encourage and enable greater use of cotton in modern nonwovens textiles. ARS, CCU research scientists are continuing to screen diverse cotton lines for unique properties that can be applied to specific, specialty use nonwoven products. Currently, properties of interest that have significant differences among eleven parent lines include hydrogen peroxide generation for antibacterial and/or wound healing applications, and flame retardancy. A population of individual cotton plants called a recombinant inbred line (RIL) population was derived from breeding the diverse cotton lines and grown in multiple years and locations and are now being screened for these properties, which should possess greater diversity than the parent lines. All parent lines and RILs have had their genomes sequenced which will facilitate identification of the gene(s) responsible for the observed fiber traits of interest. A sufficient amount of fiber from the parent lines was harvested and ginned during the previous year’s growing season and nonwoven fabric production is proceeding for advanced testing related to wound dressings with inherently elevated hydrogen peroxide generation, and flammability for specific applications and/or the reduction in chemical flame retardant additives. ARS, CCU research scientists have revealed the factors governing the thermal properties of cotton fiber by studying two varieties of brown cotton (SA-1 and MC-BL) - greater magnitudes in cellulose crystallinity and fiber diameter for SA-1, while higher extents in color depth and naturally occurring inorganic components for MC-BL. Various thermal analyses showed the superior thermal stability and combustion resistance for MC-BL as compared with those for SA-1. This finding revealed that trace amounts of inorganics and colorants have more predominant effects than crystallinity, which has been generally accepted as one of the most important factors in the thermal stability of cotton fiber, suggesting a new, efficient approach in altering the flammability of cotton fiber. ARS, CCU research scientists are conducting gene silencing experiments that will identify the key regulatory steps in the brown cotton fiber metabolic pathway responsible for the fiber color. The ultimate goal of this experiment is to inhibit formation of the brown color while still accumulating colorless precursor molecules in the fibers. Based on our previous results the enhanced flame retardancy of brown fibers is present during development while the fibers are still white. The colorless precursor molecules cause specific metals to accumulate in the fibers leading to enhanced flame retardancy. Specific genes that are responsible for brown color development will be shut down, while fibers will continue to accumulate the colorless molecules and metals. This would result in a white fiber cotton line with enhanced flame retardancy. ARS, CCU research scientists have made progress on a new idea of the nano-dispersion of functional metallic nanoparticles (particles between 1 and 100 nanometers in size) throughout the entire volume of cotton fiber. In terms of imparting the durable functionality that will not easily be removed by laundering, such nanocomposite formation is advanced over currently available surface or near surface integration methods. Screening a variety of inorganic nanoparticles suggested that silver, zinc oxide, copper nanoparticles could be good choices because they have multi-functionalities, such as antimicrobial, UV-blocking, and flame retardancy. More importantly, their synthetic methods were found to be manipulated for the proposed nanocomposite fabrication, i.e., silver and copper nanoparticles can be synthesized in the alkaline condition, which opens the internal structure of cotton fiber, and the precursor of zinc oxide nanoparticle - zinc chloride - swells the cotton. Despite its importance in the application of nanotechnology, little is known whether the nano-dispersion of metallic particles influences the microstructure of semi-crystalline cellulose fiber. ARS, CCU research scientists have found that the silver nanoparticles synthesized inside cotton fiber binds adjacent microfibrils to generate a denser microstructure along the radius of the fiber. This newly created inorganic-organic hybrid structure was attributed to the electrostatic fixation of silver nanoparticle to cellulose, which was induced by the alkaline condition. As a result, the density of cotton fiber was increased, but the linear density (mass per unit length) and the cross-sectional area of fiber were decreased. Such understanding of the microstructure of silver-cotton nanocomposite is expected to help identify future directions to create durable and controlled functionalities. ARS, CCU research scientists have developed a new technique to quantify the amounts of cellulose Iß crystal, cellulose II crystal, and amorphous (non-crystalline solid) cellulose in cotton fiber. Although there are several methods to measure the amounts of crystal and amorphous fractions, they cannot measure the percentages of cellulose Iß and cellulose II for partially mercerized cotton that has been swollen by immersion in a sodium hydroxide bath. The developed method was based on the simulation of the X-ray diffraction pattern of cotton fiber with the calculated diffraction patterns for perfect cellulose Iß and II crystals and pure amorphous cellulose. This method successfully characterized the changes in the crystalline structure of cotton resulting from the integration of silver nanoparticle.
1. An optimized chemical co-formulation enabled the practical use of a 100% raw cotton disposable disinfecting wipe with a quaternary ammonium compound (quat) biocide. The quat alkyl-dimethyl-benzyl-ammonium chloride (ADBAC) chemical was used as the active disinfecting ingredient and co-formulations contained an added salt, a low molecular weight quat, and a nonionic (uncharged) surfactant. Statistical modeling of quat depletion from solution onto 100% raw cotton nonwoven wipes allowed for the development of the optimized quat co-formulation. Efficacy testing at the level of Environmental Protection Agency registration was conducted and resulted in the following accomplishments: 1) quat adsorption onto cellulosic substrates can be minimized with inexpensive added chemistries, and 2) based on GLP level efficacy testing a 100% raw cotton disposable disinfecting wipe with an optimized ADBAC co-formulation can be used to successfully disinfect a hard surface against disease causing microorganism (i.e. - Pseudomonas aeruginosa, Methicillin Resistant Staphylococcus aureus (MRSA), and Vancomycin Resistant Enterococcus faecalis (VRE). This research was also a featured story in the June 2016 issue of AgResearch Magazine.
2. Determination of the mechanisms by which brown cotton fibers exhibit enhanced flame retardant characteristics. The link of the flame resistance of brown cotton to its color was confirmed by identifying the presence of condensed tannins using CP/MAS 13C NMR. The tannins enhanced the thermal properties of brown cotton by its capability to bind metal ions as well as its intrinsic thermal resistance. Among inorganic components, the important role of sodium was also identified. Sodium catalyzed the low temperature thermal reaction of cellulose, showing a significant negative correlation with the heat release capacity of cotton fiber. The inorganic components, predominantly sodium, and tannins interplayed to induce the self-extinguishing property of brown cotton in which the fabric no longer supports an open flame once the ignition source is removed.
3. Identification of the mutation resulting in brown color and enhanced flame retardant properties in naturally colored brown cotton fibers. Agricultural Research Service (ARS), Cotton Chemistry and Utilization (CCU) research scientists used next generation RNA and genomic DNA sequencing techniques to identify DNA molecular markers linked to the brown color and enhanced flame retardancy of brown cotton fibers. A large population developed over several years from breeding of brown and white cotton lines was used as a mapping population for the newly identified molecular markers. The causative mutation was identified as a large genomic DNA sequence inversion immediately upstream of a gene with similarity to the Arabidopsis TRANSPARENT TESTA2 gene that is a transcription factor controlling proanthocyanidin biosynthesis. This cotton gene was designated GhTT2_A07. The inversion in the brown cotton genome activates GhTT2_A07 which subsequently upregulates the entire proanthocyanidin pathway in brown fibers. This is the first report identifying the causative mutation and gene responsible in naturally colored cotton fibers. In addition to brown fiber, it was demonstrated that GhTT2-A07 is also linked to the enhanced flame retardancy of brown cotton fibers.
4. Identification of candidate genes linked to specific cotton fibers quality traits. In collaboration with the Cotton Fiber Bioscience Research Unit, ARS scientists in the Cotton Chemistry and Utilization Research Unit have identified genes and genetic loci that control cotton fiber properties including length, strength and fineness. These accomplishments included identification of the causative mutation resulting in the immature (im) mutant in cotton fibers, and identification of candidate genes responsible for enhanced fiber strength and length in the cotton lines MD 52ne and MD 90ne. Cotton fiber properties including length, strength and fineness are important for the production of both woven and nonwoven textiles, but have different relative values in each application.
5. The production of silver nanoparticles within the cotton fiber structure results in increased fiber strength. The homogeneous embedding of silver nanoparticle throughout the entire volume of cotton fiber significantly increased the strength of cotton fiber, whose statistical behavior was well described by the Weibull model. The cotton microfibrils that make up the fiber exhibited restricted mobility as a result of the nanoparticle binding and a reduction in elongation at break during fiber strength testing. With its high surface to volume ratio, the extensive contact between adjacent silver nanoparticles efficiently “glued” the microfibrils together to increase the stiffness and strength of the nanocomposite over those of the untreated control cotton fiber.
6. A limitation and improvement of a long standing method to measure the crystallinity index (CI) of cotton (the Segal method) has been made. The X-ray-based Segal crystallinity index (CI), was examined by the simulation of the X-ray diffraction patterns of raw and mercerized cotton celluloses in powder form. Due to the means of sample preparation, the Segal method underestimated the amorphous fraction for cellulose II. Accurate measurement of crystallinity and amorphous constant are required to predict and enhance cotton performance properties such as chemical modification, strength and absorbency.
7. Multiple awards for enabling the transfer of technology that enabled the use of raw cotton in a commercial baby diaper. ARS researchers in the Cotton Chemistry and Utilization Research Unit received the Southern Regional Research Center Technology Transfer Award, the ARS Mid-South Area Technology Transfer Award, the Federal Lab Consortium Excellence in Technology Transfer Award, and the National ARS Technology Transfer Award for this achievement.
Hinchliffe, D.J., Condon, B.D., Slopek, R.P., Reynolds, M.L. 2017. The adsorption of alkyl-dimethyl-benzyl-ammonium chloride onto cotton nonwoven hydroentangled substrates at the solid-liquid interface is minimized by additive chemistries. Textile Research Journal. 87(1):70-80.
Nam, S., Kim, H.J., Condon, B.D., Hinchliffe, D.J., Chang, S., Mccarty, J.C., Madison, C.A. 2016. High resistance to thermal decomposition in brown cotton is linked to tannis and sodium content. Cellulose. 23(2):1137-1152.
Naoumkina, M.A., Thyssen, G.N., Fang, D.D., Hinchliffe, D.J., Florane, C.B., Jenkins, J.N. 2016. Small RNA sequencing and degradome analysis of developing fibers of short fiber mutants Ligon-lintles-1 (Li1) and -2 (Li2) revealed a role for miRNAs and their targets in cotton fiber elongation. BMC Genomics. 17:360. https://doi.org/10.1186/s12864-016-2715-1.
Thyssen, G.N., Fang, D.D., Zeng, L., Song, X., Delhom, C.D., Condon, T.L., Li, P., Kim, H.J. 2016. The immature fiber mutant phenotype of cotton (Gossypium hirsutum) is linked to a 22-bp frame-shift deletion in a mitochondria targeted pentatricopeptide repeat gene. G3, Genes/Genomes/Genetics. 6:1627-1633.
Islam, M.S., Fang, D.D., Thyssen, G.N., Delhom, C.D., Liu, Y., Kim, H.J. 2016. Comparative fiber property and transcriptome analyses reveal key genes potentially related to high fiber strength in cotton (Gossypium hirsutum L.) line MD52ne. Biomed Central (BMC) Plant Biology. 16:36.
Islam, M.S., Zeng, L., Thyssen, G.N., Delhom, C.D., Kim, H.J., Li, P., Fang, D.D. 2016. Mapping by sequencing in cotton (Gossypium hirsutum) line MD52ne identified candidate genes for fiber strength and its related quality attributes. Theoretical and Applied Genetics. 129:1071-1086.