Elena Graves

Flame resistant cotton/polyester carpet materials

Cotton/polyester carpet materials are resistant to surface flame spread after esterification of the cellulosic fibers with polycarboxylic acid and suitable catalyst. The crosslinked cellulose-containing materials passed the re quired flammability standards for carpet when subjected to the methenamine pill test. This test is much less severe than the rigorous vertical flame test method required for textiles designated for other end uses. Cotton-containing carpet materials finished with 5-10% polycarboxylic acid, such as 1,2,3,4-butanetetracarboxylic acid (BTCA) or citric acid, and sodium phosphate, sodium hypophosphite, sodium bicarbonate or sodium carbonate catalyst were found to meet test method specifications when proper processing and fixation conditions were employed. Specific details of processing conditions and results of flammability tests are presented.

Phosphorylation of Cellulose with Some Phosphonic Acid Derivatives

Cellulose is readily phosphorylated with phosphonic acid derivatives upon heating at elevated temperatures. In this paper, various properties of cotton fabrics phosphorylated with 1-hydroxyethylidene-1,1-diphosphonic acid, phenyl phosphonic acid, 2-carboxyeth ylphosphonic acid. and N-(phosphonomethyl)iminodiacetic acid are investigated. Phos phorylation occurs only in the presence of urea as expected. Without urea, there is discoloration as well as severe degradation of the fabric, as indicated by tensile strength reduction. Good reactivity is achieved by curing at 170°C for 2-4 minutes, and reaction efficiency is determined by phosphorus analysis. The best overall results are achieved with 1-hydroxyethylidene-1,1-diphosphonic acid. Although there is fabric discoloration upon curing with this agent, it is much less than that with the other derivatives. Discoloration upon curing of phosphorylated cottons is reduced by incorporating 1-4% dicyandiamide in the treatment formulation. Physical properties of the phosphorylated fabrics are dis cussed, along with thermogravimetric analyses of the substrates.

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.

Electrokinetic and Hemostatic Profiles of Nonwoven Cellulosic/Synthetic Fiber Blends with Unbleached Cotton

Greige cotton contains waxes and pectin on the outer surface of the fiber that are removed when bleached, but these components present potential wound dressing functionality. Cotton nonwovens blended with hydrophobic and hydrophilic fibers including viscose, polyester, and polypropylene were assessed for clotting activity with thromboelastography (TEG) and thrombin production. Clotting was evaluated based on TEG measurements: R (time to initiation of clot formation), K (time from end of R to a 20 mm clot), α (rate of clot formation according to the angle tangent to the curve as K is reached), and MA (clot strength). TEG values correlate to material surface polarity as measured with electrokinetic parameters (ζplateau, Δζ and swell ratio). The material surface polarity (ζplateau) varied from −22 to −61 mV. K values and thrombin concentrations were found to be inversely proportional to ζplateau with an increase in material hydrophobicity. An increase in the swell ratios of the materials correlated with decreased K values suggesting that clotting rates following fibrin formation increase with increasing material surface area due to swelling. Clot strength (MA) also increased with material hydrophobicity. Structure/function implications from the observed clotting physiology induced by the materials are discussed.

Fluid handling and fabric handle profiles of hydroentangled greige cotton and spunbond polypropylene nonwoven topsheets

Wettable nonwoven topsheets are traditionally spunbond polypropylene nonwoven fabrics. The fluid handling performance of hydroentangled greige cotton nonwovens was studied to determine their suitability for topsheet applications based upon analysis of fluid rewet, strikethrough, and acquisition properties; and the relative contributions of nonwoven cotton’s cellulosic and wax components to hydrophobic and hydrophilic fluid transport properties are addressed. It was observed that mechanically cleaned greige cotton nonwovens exhibit certain fluid handling properties that are similar to polypropylene spunbond-meltblown topsheets, partly as a result of the residual wax content. Subsequently, the surface polarity, swelling, and moisture uptake of 100% greige cotton and 50:50 blends of greige cotton and polypropylene hydroentangled nonwovens were studied in comparison with the performance of a commercially available 100% polypropylene spunbond-meltblown topsheets. The surface polarity, swelling, and wettability values obtained from electrokinetic and water contact angle analysis were found to be in agreement with the hydrophobic polypropylene topsheets. Additionally, comfort assessment was undertaken based upon fabric handle profiles using the Leeds University Fabric Handle Evaluation System, which is an objective evaluation based on the quantification of fabric buckling deformations. Of the fabrics studied in this work, 50:50 greige cotton/polypropylene hydroentangled fabrics were the softest as determined by the Leeds University Fabric Handle Evaluation System and exhibited fluid handling properties consistent with the requirements of commercial topsheets.

Structure/Function Analysis of Nonwoven Cotton Topsheet Fabrics: Multi-Fiber Blending Effects on Fluid Handling and Fabric Handle Mechanics

Greige cotton (GC) has attracted interest in recent years as an eco-friendly, functional fiber for use in nonwoven topsheet materials. GC imparts favorable fluid management and sensorial properties associated with urinary liquid transport and indices related to comfort in wearable incontinence nonwovens. Nonwoven GC has material surface polarity, an ambient moisture content, and a lipid/polysaccharide matrix that imparts positive fluid mechanic properties applicable to incontinence management topsheet materials. However, a better understanding of the connection between functionality and compositional aspects of molecular, mechanical, and material property relations is still required to employ structure/function relations beyond a priori design. Thus, this study focuses on the relation of key indices of material fluid and sensorial functions to nonwoven topsheet composition. Greige cotton, polypropylene, bleached cotton, and polyester fiber blends were hydroentangled at 60, 80, and 100 bar. Greige cotton polypropylene and bleached cotton were blended at ratios to balance surface polarity, whereas low percentages of polyester were added to confer whiteness properties. Electrokinetic and contact angle measurements were obtained for the hydroentangled nonwovens to assess surface polarity in light of material composition. Notably, materials demonstrated a relation of hydrophobicity to swelling as determined electrokinetically by Δζ, ζplateau, and contact angles greater than 90°. Subsequently, three blended nonwoven fabrics were selected to assess effects on fluid management properties including topsheet performance indices of rewet, strikethrough, and fluid handling (rate and efficiency of transport to the absorbent core). These materials aligned well with commercial topsheet fluid mechanics. Using the Leeds University Fabric Handle Evaluation System (LUFHES), the nonwovens were tested for total fabric hand. The results of the LUFHES measurements are discussed in light of fiber contributions. Fiber ratios were found to correlate well with improvement in softness, flexibility, and formability. This study provides insights that improves the understanding of the multifunctional properties accessible with greige cotton toward decisions valuable to selecting greige cotton as an environmentally friendly fiber for nonwoven topsheets.