Microwave Assisted Preparation of Flame Resistant Cotton Using Economic Inorganic Materials

Innovative approaches for preparing flame retardant cotton fabrics were employed by utilizing a microwave-assisted technique with a minimum amount of co-solvent. Our attempts at flame retardant cotton fabrics treated with low cost inorganic formulations, such as urea and diammonium phosphate, were done successfully. The evidence of flame retardant chemical penetrations or surface modification of cotton fabrics was confirmed by scanning electron microscope (SEM) and the treated cotton fabrics were evaluated by flammability tests, such as 45° angle (clothing textiles test), vertical flame (clothing textile test) and limiting oxygen index (LOI). For formulations with urea only, LOI values of treated fabrics were 21.0–22.0% after add-on values for the formulation were 5.16–18.22%. For formulations comprising urea with diammonium phosphate, LOI values were greater than 29.0% after add-on values for the formulation were 1.85–7.73%. With the formulation comprising urea and diammonium phosphate, all treated fabrics passed the vertical flame test for add-on values 5.34–7.73%. Their char lengths were less than half the length of the original fabric and after-flame and after-glow times were less than 3.2 s. Additional thermal properties of desired products will be discussed using thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC)

Development of an environmentally friendly halogen-free phosphorus–nitrogen bond flame retardant for cotton fabrics

A novel flame retardant diethyl 4-methylpiperazin-1-ylphosphoramidate (CN-3) containing phosphorous and nitrogen was prepared. Its chemical structure was confirmed by nuclear magnetic resonance (1H-, 13C-, and 31P-NMR), Fourier transform infrared spectroscopy, and elemental analysis. Print cloth and twill fabrics were treated with CN-3 to achieve different levels of add-on (7–22 wt% add-ons for print cloth and 3–18wt% add-ons for twill). Thermogravimetric analysis, vertical flame test, and limiting oxygen index (LOI) were performed on the treated cotton fabrics and showed promising results. When the treated print cloth and twill fabric samples were tested using the vertical flame test (ASTM D6413-08), we observed that the ignited fabrics self-extinguished and left behind a streak of char. Treated higher add-ons fabrics were neither consumed by flame nor produced glowing ambers upon self-extinguishing. LOI (ASTM 2863–09) was used to determine the effectiveness of the flame retardant on the treated fabrics. LOI values increased from 18 vol% oxygen in nitrogen for untreated print cloth and twill fabrics to maximum of 28 and 31 wt% for the highest add-ons of print cloth and twill, respectively. The results from cotton fabrics treated with CN-3 demonstrated a higher LOI value as well as a higher char yield because of the effectiveness of phosphorus and nitrogen as a flame retardant for cotton fabrics. Furthermore, FT-IR and SEM were used to characterize the chemical structure on the treated fabrics as well as the surface morphology of char areas of treated and untreated fabrics

Silver(I) Antimicrobial Cotton Nonwovens and Printcloth

In this paper we discuss the preparation and comparative evaluation of silver (I) [Ag(I)] nonwoven and woven antimicrobial barrier fabrics generated from commercial calcium-sodium alginates and laboratory prepared sodium carboxymethyl (CM) cotton nonwovens and CM-cotton printcloth for potential use as wound dressings. Degrees of CM substitution (DS) in cotton nonwoven and printcloth samples by titrimetry were 0.38 and 0.10, respectively. Coordination of Ag(I) with carboxylates on fabrics was effected by ion exchange and nitrates were removed by washing to mitigate nitrate ion toxicity issues. Durability of silver coordinated fabrics was tested by soaking them in deionized water with slight agitation at 50 degrees C. Ag(I) alginates and nonwoven Ag(I)-CM-cottons lost structural integrity in water. Ag-CM-cotton printcloth samples retained structural integrity even after four soak-and-dry cycles, were smooth to the touch when dry, and were smoother when moistened. They could be easily peeled from wound surfaces without inducing trauma. Solid-state carbon-13 (C-13) nuclear magnetic resonance (NMR) spectrometry was used to observe changes in carbonyl resonances in Ag(I) alginates and Ag(I)-CM-printcloth, and the chemical shift positions of carbonyl resonances of uncoordinated and Ag(I) coordinated fabrics did not change. Inductively coupled plasma-mass spectrometry (ICP-MS) was used following fabric digestion to determine the total Ag(I) ion content in fabrics. Ag(I) alginates were found to hold about 10-50 mg Ag(I) per gram fabric; and Ag(I) cotton woven and nonwoven fabrics held about 5-10 mg Ag(I) ions per gram fabric. Kinetic release of Ag(I) after soaking once in physiological saline was studied with ICP-MS to estimate the availability of Ag(I) upon a single exchange with Na(I) ions on wound surfaces. Alginates released between similar to 13 and 28% of coordinated Ag(I), and CM-cotton nonwovens and CM-cotton printcloth released similar to 14 and 3% of coordinated Ag(I) ions, respectively. Finally, Ag(I) alginates and Ag-CM-cotton printcloth samples were evaluated against Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae. Ag(I) alginates suppressed 99.95% of bacterial growth in vitro. Even after four soak-and-dry cycles in deionized water Ag(I)-CM-cotton printcloth suppressed 99.99% of bacterial growth in vitro. Published in 2007 by John Wiley & Sons, Ltd

Epoxy Phosphonate Crosslinkers for Providing Flame Resistance to Cotton Textiles

Two new monomers (2-methyl-oxiranylmethyl)-phosphonic acid dimethyl ester (3) and [2-(dimethoxy-phosphorylmethyl)-oxyranylmethyl]-phosphonic acid dimethyl ester (6) were prepared and used with dicyandiamide (7) and citric acid (8) to impart flame resistance to cotton plain weave, twill, and 80:20-cotton/polyester fleece fabrics. Monomers 3 and 6 were prepared from methallyl chloride (1) and 3-chloro-2-chloromethylpropene (4) respectively via a two-step phosphorylation epoxidation sequence in 79.3 and 67.5% overall yields. H-1 and C-13 nuclear magnetic resonance (NMR) and gas chromatographic mass spectrometry (GCMS) data were used to confirm their structures. Decomposition of monomers 3 and 6 in nitrogen by thermogravimetric analysis (TGA) occurred at 110 and 220 degrees C, respectively. The mixtures of 3:7:8 and 6:7:8 (in 2:1:1 ratio) exhibited peak-curing temperatures by differential scanning calorimeter (DSC) at 125 and 150 degrees C and the temperatures were deemed suitable for curing treated fabrics without marring them. Flame-retardant treatments were applied by the pad-dry-cure methods. All untreated fabrics showed limiting oxygen index (LOI) values of about 18% oxygen in nitrogen. For formulations with monomer 3, LOI values for the three types of treated fabrics were greater than 25.5% when add-on values for the formulation were 17.4, 12.7, and 21.1%. For formulations comprising monomer 6, LOI values were greater than 28.6% when add-on values for the formulation were 18.3, 13.1, and 16.7%. With the formulation comprising monomer 3, the three fabrics passed the vertical flame test when add-on values were 21.6, 12.7, and 23.5%, respectively; and with the formulation comprising monomer 6, they passed the vertical flame test when add-on values were 13.8, 8.4, and 18.0%. In all cases char lengths of fabrics that passed the vertical flame test were less than 50% of original length and after-flame time was 0 sec and after-glow time was less than 2 sec. Published in 2007 by John Wiley & Sons, Ltd

Ascorbic Acid as an Adjuvant to Unbleached Cotton Promotes Antimicrobial Activity in Spunlace Nonwovens

The development of affordable, effective, and environmentally friendly barrier fabrics is a current goal in antimicrobial textile development. The discovery of new routes to achieve non-toxic naturally occurring molecules with antimicrobial activity is of interest in the development of materials that promote wound healing, improve hygiene, and offer protection against nosocomial infection. Highly cleaned and sterile unbleached cotton has constituents that produce hydrogen peroxide at levels commensurate with those that favor cell signaling in wound healing. Here, we show the antimicrobial and antiviral properties of spunlaced griege cotton-containing nonwovens treated with ascorbic acid formulations. The mechanism of action occurs through the promotion of enhanced hydrogen peroxide activity. The levels of hydrogen peroxide activity afford antimicrobial activity against Gram-negative and Gram-positive bacteria and antiviral activity against MS2 bacteriophages. Spun-bond nonwoven unbleached cotton was treated with ascorbic acid using traditional pad-dry-cure methods. An assessment of antibacterial and antiviral activity against Staphylococcus aureus, Klebsiella pneumoniae, and MS2 bacteriophages with the AATCC 100 test method showed a 99.99% inhibitory activity. An approach to the covalent attachment of ascorbic to cellulose through citric acid crosslinking chemistry is also discussed. Thus, a simple, low-cost approach to antimicrobial and antiviral cotton-based nonwovens applicable to dressings, nosocomial barrier fabrics, and face masks can be adopted by combining ascorbic acid with spunlace greige cotton nonwoven fabrics

Ascorbic Acid as an Adjuvant to Unbleached Cotton Promotes Antimicrobial Activity in Spunlace Nonwovens

The development of affordable, effective, and environmentally friendly barrier fabrics is a current goal in antimicrobial textile development. The discovery of new routes to achieve non-toxic naturally occurring molecules with antimicrobial activity is of interest in the development of materials that promote wound healing, improve hygiene, and offer protection against nosocomial infection. Highly cleaned and sterile unbleached cotton has constituents that produce hydrogen peroxide at levels commensurate with those that favor cell signaling in wound healing. Here, we show the antimicrobial and antiviral properties of spunlaced griege cotton-containing nonwovens treated with ascorbic acid formulations. The mechanism of action occurs through the promotion of enhanced hydrogen peroxide activity. The levels of hydrogen peroxide activity afford antimicrobial activity against Gram-negative and Gram-positive bacteria and antiviral activity against MS2 bacteriophages. Spun-bond nonwoven unbleached cotton was treated with ascorbic acid using traditional pad-dry-cure methods. An assessment of antibacterial and antiviral activity against Staphylococcus aureus, Klebsiella pneumoniae, and MS2 bacteriophages with the AATCC 100 test method showed a 99.99% inhibitory activity. An approach to the covalent attachment of ascorbic to cellulose through citric acid crosslinking chemistry is also discussed. Thus, a simple, low-cost approach to antimicrobial and antiviral cotton-based nonwovens applicable to dressings, nosocomial barrier fabrics, and face masks can be adopted by combining ascorbic acid with spunlace greige cotton nonwoven fabrics

Understanding the Mechanism of Action of Triazine-Phosphonate Derivatives as Flame Retardants for Cotton Fabric

Countless hours of research and studies on triazine, phosphonate, and their combination have provided insightful information into their flame retardant properties on polymeric systems. However, a limited number of studies shed light on the mechanism of flame retardancy of their combination on cotton fabrics. The purpose of this research is to gain an understanding of the thermal degradation process of two triazine-phosphonate derivatives on cotton fabric. The investigation included the preparation of diethyl 4,6-dichloro-1,3,5-triazin-2-ylphosphonate (TPN1) and dimethyl (4,6-dichloro-1,3,5-triazin-2-yloxy) methyl phosphonate (TPN3), their application on fabric materials, and the studies of their thermal degradation mechanism. The studies examined chemical components in both solid and gas phases by using attenuated total reflection infrared (ATR-IR) spectroscopy, thermogravimetric analysis coupled with Fourier transform infrared (TGA-FTIR) spectroscopy, and 31P solid state nuclear magnetic resonance (31P solid state NMR), in addition to the computational studies of bond dissociation energy (BDE). Despite a few differences in their decomposition, TPN1 and TPN3 produce one common major product that is believed to help reduce the flammability of the fabric

Multi-omics analysis of pigmentation related to proanthocyanidin biosynthesis in brown cotton (Gossypium hirsutum L.)

Naturally-colored brown cotton (NBC) fiber is an environmentally friendly raw source of fiber for textile applications. The fiber of some NBC cultivars exhibits flame-retardant properties, which can be used in textiles that require flame resistance. Proanthocyanidins or their derivatives are responsible for the brown pigment in NBC; however, how flame retardancy is related to pigmentation in NBC is poorly understood. To gain insight into brown pigment biosynthesis, we conducted comparative transcripts and metabolites profiling analysis of developing cotton fibers between the brown (MC-BL) and white (MC-WL) cotton near-isogenic lines (NILs), genetically different only in the Lc1 locus. In this study, mass spectrometry was used to detect metabolites in BL and WL developing fibers at 8, 12, 16, 20, 24, 36, and 40 days post anthesis (DPA) and mature fibers. Transcripts analysis was performed at two critical fiber developmental points, 8 DPA (fiber elongation) and 20 DPA (secondary cell wall deposition). We found 5836 (ESI MS positive mode) and 4541 (ESI MS negative mode) metabolites significantly different accumulated between BL and WL. Among them, 142 were known non-redundant metabolites, including organic acids, amino acids, and derivatives of the phenylpropanoid pathway. Transcript analysis determined 1691 (8 DPA) and 5073 (20 DPA) differentially expressed genes (DEGs) between BL and WL, with the majority of DEGs down-regulated at 20 DPA. Organic acids of the citric acid cycle were induced, while most of the detected amino acids were reduced in the MC-BL line. Both cis- and trans-stereoisomers of flavan-3-ols were detected in developing MC-WL and MC-BL fibers; however, the gallocatechin and catechin accumulated multiple times higher. Gas chromatography-mass spectrometry (GC-MS) analysis of fatty acids determined that palmitic acid long-chain alcohols were the main constituents of waxes of mature fibers. Energy-dispersive X-ray spectrometry (EDS) analysis of mature fibers revealed that potassium accumulated three times greater in MC-BL than in MC-WL mature fibers. This study provides novel insights into the biosynthesis of pigments and its association with flame retardancy in NBC fibers