SeChin Chang

Flame retardant behavior of polyelectrolyte-clay thin film assemblies on cotton fabric.

Cotton fabric was treated with flame-retardant coatings composed of branched polyethylenimine (BPEI) and sodium montmorillonite (MMT) clay, prepared via layer-by-layer (LbL) assembly. Four coating recipes were created by exposing fabric to aqueous solutions of BPEI (pH 7 or 10) and MMT (0.2 or 1 wt %). BPEI pH 10 produces the thickest films, while 1 wt % MMT gives the highest clay loading. Each coating recipe was evaluated at 5 and 20 bilayers. Thermogravimetric analysis showed that coated fabrics left as much as 13% char after heating to 500 degrees C, nearly 2 orders of magnitude more than uncoated fabric, with less than 4 wt % coming from the coating itself. These coatings also reduced afterglow time in vertical flame tests. Postburn residues of coated fabrics were examined with SEM and revealed that the weave structure and fiber shape in all coated fabrics were preserved. The BPEI pH 7/1 wt % MMT recipe was most effective. Microcombustion calorimeter testing showed that all coated fabrics reduced the total heat release and heat release capacity of the fabric. Fiber count and strength of uncoated and coated fabric are similar. These results demonstrate that LbL assembly is a relatively simple method for imparting flame-retardant behavior to cotton fabric. This work lays the foundation for using these types of thin film assemblies to make a variety of complex substrates (foam, fabrics, etc.) flame resistant.

Intumescent All‐Polymer Multilayer Nanocoating Capable of Extinguishing Flame on Fabric

According to the National Fire Protection Association (NFPA), there were an estimated 1.3 million fi res in the United States in 2009, which resulted in 3010 civilian deaths (one every 175 minutes), 17 050 injuries (one every 31 minutes), [ 1 ] and direct property loss estimated at

Synthesis of a novel flame retardant containing phosphorus-nitrogen and its comparison for cotton fabric

12.5 billion. There were more than 40 000 deaths worldwide from fi re in 2006 and it cost every country an average of 1% of their gross domestic product in property loss, medical services for burn victims, etc. [ 2 ] Firerelated issues continue to drive the development of materials that can reduce fi re risk to save lives and protect property, but any fl ame retardants used to reduce that fi re risk have to meet various safety standards to reduce the deleterious effect on the environment or human health. Textiles in particular require effective anti-fl ammable performance combined with minimal enviornmental impact because they are often washed and fl ame retardant additives can leach out of the fabric and into the environment. [ 3 , 4 ] There are numerous strategies used to make textile fi bers fl ame retardant: surface treatment, fi re-retardant additives or co-monomers in synthetic fi bers, nanocomposite technology, heat-resistant and inherently fi re-retardant fi bers, and fi ber blending. [ 5 ] More recently, layer-by-layer (LbL) assembly has been used as a surface treatment to impart fl ame resistance to cotton fabric by coating each individual fi ber with a claypolymer nanobrick wall. [ 6 ]

Enhanced thermal and combustion resistance of cotton linked to natural inorganic salt components

A new charring agent, a derivative of cyanuric chloride, mono-substituted, dimethyl (4,6-dichloro-1,3,5-triazin-2-yloxy)methylphosphonate (CN), was synthesized in good yield and characterized. Its flame retardant and thermogravimetric properties were compared to those of the di-substituted compound, tetramethyl (6-chloro-1,3,5-triazine-2,4-diyl)bis(oxy)bis (methylene)diphosphonate (CN-1), which was prepared in previous work. All untreated fabric showed limiting oxygen index (LOI) values of about 18 vol% oxygen in nitrogen. Fabrics treated with CN at 5–21 wt% add-ons had high LOI values of 30–40 vol%, while fabrics treated with CN-1 at 5–19 wt% add-ons had low to high LOI value of 20–36 vol%. In 45° angle flammability tests, all treated fabrics with CN and CN-1 were passed and some fabrics were not igniting at all. Thermal degradation revealed that onset of degradation and the char yield of CN compound is higher than that of CN-1. Treated fabric with CN, 21 wt% add-on, had an onset of degradation of 240 °C, while fabric treated with CN-1, 19 wt% add-on displayed an onset of degradation of 230 °C. Despite the differences in onset temperature, the two samples provided almost the same char yield at 600 °C, 35 and 36 %. With Fourier transform infrared (FTIR), samples of treated/unburned and treated/burned of CN and CN-1 showed the same functional groups and revealed the disappearance of triazine group and P-O-methyl after burning. Additionally, scanning electron microscopy (SEM) showed that both CN and CN-1 acted as flame retardants by the same mechanism and characterized the surface morphology of the flame retardant treated twill fabrics.

Physical and combustion properties of nonwoven fabrics produced from conventional and naturally colored cottons

Abstract A comparison of the thermal decomposition and combustion characteristics of raw and scoured cottons has demonstrated a mechanistic link caused by the presence of inorganic salts in raw cotton, which enhances resistance to heat and flame. Thermogravimetry, differential thermogravimetry, and microscale combustion calorimetry were used to examine the thermal decomposition kinetics and thermal stability of cotton. During pyrolysis, both raw cotton nonwoven and woven fabrics exhibited a slower decomposition with a larger initial weight loss and produced a greater char yield, as compared to the fabrics after scouring, which removes most inorganic components from cotton. The activation energy (Ea) values, calculated using the Kissinger method, the Flynn–Wall–Ozawa method, and the modified Coats–Redfern method, were consistently determined to be smaller for raw cotton than for scoured cotton. The analyses of cotton fabrics heated at elevated temperatures by 13C CP/MAS NMR and ATR-FTIR showed that trace quantities of inorganic components promoted the formations of oxygenated moieties at low temperatures and aliphatic intermediate char. In the combustion, raw cotton exhibited a much smaller heat release capacity and a smaller total heat release than scoured cotton, indicating enhanced thermal stability when the inorganic components are intact.

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

A comparative study was conducted to identify the effects of processing on physical and combustion properties of needlepunched (NP) and hydroentangled (H-E) nonwoven fabrics produced from fibers of white fiber cotton and a naturally colored brown fiber cotton. A significantly higher degree of flame retardancy (FR) in was observed in fabrics produced from brown cotton fibers compared with white fibers. Calorimetry revealed lower heat release capacity, lower peak heat release rate, and total heat release from brown fibers compared with white fibers. The ash content was also higher in brown fiber samples suggesting higher levels of inorganic elements in the brown fibers. Elemental analyses revealed brown cotton fibers had higher levels of known FR elements including phosphorous and magnesium. The H-E process reduced FR in brown fabrics, which also correlated with a reduction in phosphorous. However, brown H-E fabrics still maintained higher FR than white H-E fabrics. Water content analysis indicated higher water levels in brown fibers, particularly brown greige fibers, which correlated with increased FR. Processing parameters such as energy of H-E did not affect combustion of the two fabric types. Scouring of the brown fiber fabrics reduced, but did not remove coloration, while scouring and bleaching removed the brown color completely. Scouring alone, or scouring and bleaching, completely removed the higher FR properties of the brown fiber fabrics. The results indicate that the mechanism of FR in brown cotton fibers is dependent on multiple compositional factors that may include element content, water content, and compounds related to coloration.

The application of ultrasound and enzymes in textile processing of greige cotton

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.

Surface Coating for Flame-Retardant Behavior of Cotton Fabric Using a Continuous Layer-by-Layer Process

HighlightsUltrasound‐enhanced enzymatic scouring of greige cotton textiles leads to a greener processing method.Newly‐discovered polygalacturonase enzymes perform as well as commercially‐available enzyme.Optimized ultrasonic processing parameters indicate low enzyme concentration/high frequency combination performs best. ABSTRACT A review is reported herein of the research progress made at the USDAs Southern Regional Research Center to provide an ultrasound and enzymatic alternative to the current textile processing method of scouring greige cotton textile with caustic chemicals. The review covers early efforts to measure pectin and wax removal from greige cotton textiles using standard wicking methodology and further describes an investigation of newly discovered polygalacturonase enzymes as bioscouring agents. Additional research is reviewed involving efforts to characterize and optimize the ultrasound‐enhanced enzymatic scouring process through a statistical examination of the operating parameters of power, enzyme concentration, ultrasonic frequency and time.