Studies on the temperature dependence of extinction oxygen index values for cellulosic fabrics. I. Cotton

The concept of extinguishability as a measure of textile flammability is reviewed. Definition and determination of extinction oxygen index enables a parameter to be defined from which the effects of ignition time and fabric structure may be removed. This so-called extinction oxygen index (EOI) and the derived value at zero ignition time [EOI]₀ more exactly define the burning/nonburning fabric boundary than does the more widely used limiting oxygen index (LOI). This first paper reports the determination of EOI and [EOI]₀ values for a series of cotton fabrics in the temperature range 20–200°C. The influence of the various fabric parameters of area density, air permeability, sample thickness, bulk density, and moisture content was investigated. The advantages of using the EOI rather than the LOI concept as a measure of textile flammability is indicated in the discussion of the results of this study with reference to previous work concerned with LOI data for cotton. In particular, the significance that environmental temperature has on EOI and related parameters reported here and previously reported LOI data is discussed in terms of various published models which define the burning/extinction threshold.     

Ignition of a radiating gas by an incandescent surface

Conclusions The fundamental regularities of ignition of a radiating and absorbing gas by an incandescent surface are examined. In the case of an optically thin medium characteristic for high-temperature ignition, the problem is solved in the traditional stationary and nonstationary formulations [8]. It is shown that radiant heat transfer plays an essential part in the gas ignition process, in particular, the process can be accelerated and retarded in an optically thin gas medium because of radiant heat exchange. The case of an optically dense gasl _kb/l _o corresponds to radiant heat conduction, and therefore, does not result in a change in the ignition time but only to an increase in the scale of the lengthl _o. For intermediate values ofl _kb/l _o the dependence of on parameters governing the energetics of radiant heat transfer is complex in nature and can only be analyzed numerically in each specific case. The development of a suitable model of radiation heat exchange is the fundamental difficulty here.Minsk. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 1, pp. 15–21, January–February, 1990.     

The use of DTA to study spontanceous ignition of cellulose

The use of differential thermal analysis has enabled spontaneous ignition behaviour of cotton cellulose to be investigate. The temperature. T_i, at which the onset of spontaneous ignition occurs is recorded as a function of the oxygen concentration of the flowing oxygen-nitrogen atmosphere to which the cellulose sample is exposed in the DTA furnace, when heated at a defined heating rate. The dependence of T_i, on heating rate has enabled the activation energy, E_p, of the rate-determining flammable pyrolysis product reaction to the determined using both a previously derived simple kinetic model and the technique of Ozawa. E_p, increases from a lower limiting value of 112 kJ mol^?1 at zero oxygen concentration to an asymptote value of 169 kJ mol^?1 at oxygen volume concentrations above 30%. This effect is described in terms of oxygen catalysis of competing pyrolysis routes. At a given heating rate, increased oxygen concentration reduces T_i. A plot of 1/T_i versus In [O₂] gives two liner regions which intersect at an oxygen concentration of about 20%, suggesting that two combustion mechanisms exist, one above and the other below this value. Below this concentration, which is similar to the conventional limiting oxygen for cellulose, significant char remains, suggesting that ignition of gaseous products only occurs. If the difference in slopes is sttributed to the variations in E_p with oxygen concentration, then a value for the activation energy of gaseous product oxidation, E_ox = 215 kJ mol^?1 is derived.     

Synergistic action of Sb2O3 with bromine-containing flame retardant in polyolefins: 3—The relationship between certain combustion variables

The combustion of polypropylene flame-retarded by the synergistic action between Sb₂O₃ and bromine-containing flame retardants has been studied. From the relationship between a number of the variables, a parameter quantatively reflecting the flame retardant effect has been found. With the addition of flame retardant, the rate of weight loss, the CO and CO₂ emission rates and heat release all decrease while smoke density increases. These effects were considered to depend on the concentration of HBr gas in the pyrolysates released into the gas phase (i.e., dW_HBr/dW, HBr flux ensity), and the following equations were obtained: η*(dW/dt)_max, which approximately corresponds to the oxidation velocity of pyrolized hydrocarbon, is inversely proportional to the HBr flux density. As the conversion of CO to CO₂ was almost independent of the amount of flame retardants added, the flame retardant effect of bromine-containing flame retardants was considered to be a retardant effect of the initial oxidation reaction at the gas liquid interface. Moreover, η* is almost proportional to the combustion efficiency η, which was obtained from the heat release measured in the flaming region. The heat release is therefore considered to be governed by the HBr flux density.     

Effect of titanium dioxide on the flame‐retardant finishing of cotton fabric

In this study, titanium dioxide (TiO₂) or nano titanium dioxide (nano‐TiO₂) was used as a cocatalyst in the flame‐retardant (FR) formulation of N‐methylol dimethylphosphonopropionamide (Pyrovatex CP New, FR), melamine resin [Knittex CHN, crosslinking agent (CL)], and phosphoric acid (PA) for cotton fabrics to improve the treatment effectiveness and minimize the side effects of the treatment. For FR‐treated cotton fabrics, the flame extinguished right after removal of the ignition source with no flame spreading. However, after neutralization and/or home laundering, FR–CL‐treated specimens failed the flammability test, whereas the opposite results were obtained from FR–CL–PA‐treated specimens. A noticeable result was that the TiO₂/nano‐TiO₂ cocatalyst had a significant effect on decreasing the flame‐spread rate. Thermal analysis found that the FR‐treated specimens without wet posttreatment showed two endothermic peaks representing the phosphorylation of cellulose and acid‐catalyzed dehydration. In addition, the treated fabrics showed some new characteristic peaks in their chemical structures; these were interpreted as carbonyl bands, CH₂ rocking bands, and CH₃ asymmetric and CH₂ symmetric stretching. The surface morphology of the FR–CL–PA‐treated cotton specimens showed a roughened and wrinkled fabric surface with a high deposition of the finishing agent that had a lower breaking load and tearing strength, which resulted from the side effects of the CL used. However, the addition of a TiO₂ or nano‐TiO₂ cocatalyst could compensate for the reduction in the tensile strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Antibacterial,flame retardant,and physico‐chemical properties of cotton fabric graft copolymerized with a binary mixture of acrylonitrile and 4‐vinylpyridine

Modification of cotton fabric has been carried out through chemically induced graft copolymerization of binary mixture of acrylonitrile (AN) and 4‐vinyl pyridine (4‐VP) using ceric ammonium nitrate, (CAN) as initiator. Maximum percentage of grafting (151.28%) has been obtained at [4‐VP] = 0.376 mol L^?1 and [AN] = 1.221 mol L^?1, [CAN] = 0.0255 mol L^?1 and [HNO₃] = 0.9585 mol L^?1 in 25mL of water at 70°C in 180 min. Post quarternization and phosphorylation reactions of the grey and grafted cotton fabrics have been carried out to study their antibacterial and flame retardant properties respectively. The fabrics have been characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The physico‐chemical properties such as wettability, moisture regain, crease recovery and tensile strength of the grey and grafted cotton fabric have also been evaluated. The modified fabric has been shown to exhibit excellent antibacterial and flame retarding properties with improved physico‐chemical properties except for the mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40415.     

Flammability testing of pure and flame retardant-treated cotton fabrics

A Controlled-atomosphere cone calorimeter was used to investigate the burning of pure and flame retardant-treated cotton fabrics. The condensed-phase flame retardants used were Morguard (containing ammonium dihydrogen phosphate and diammonium hydrogen phoisphate) and Nochar (containing ammonium sulfate and a sodium salt). The fabrics were tested at 25 kW m^?2 incident heat flux in environments containing 15–30% oxygen. The flame retardants increased the time to ignition, residue yield, and CO and CO₂ yields. The flame retardants decreased the peak and average mass loss rates, the peak and average heat release rates, the effective heat of combustion at peak heat release rate, and the propensity to flashover. The effect of oxygen concentration on the burning of pure and flame retardant-treated cotton fabrics has also been investigated. The flame retardants had better performance when the treated fabrics burned in the lower oxyge concentrations. The result of this study indicate that the controlled-atmosphere cone calorimeter is a good tool for studying the effect of flame retardant and oxygen concentration on the burning of materials.     

Influence of moisture on the flame retardance of textile fabrics

For cotton fabric not treated with a flame retardant (FR), the oxygen index (OI) increases slowly but at a constant rate with moisture content (MC). Above a MC of roughly 33% which roughly equals the water fiber saturation point of the cotton fiber, the increase becomes more rapid but the relation appears to remain linear. The relation between OI and MC is also linear for all the FR cotton fabrics examined up to an OI of at least 40. It is suggested that the moisture in the FR samples is not reducing flammability by entering into solid and/or gaseous phase reactions but by absorbing thermal energy owing to the endothermic process of heating and vaporization. Empirical relations appear to be present between the inherent hydrophilicity of the FR cotton fabrics and the OI of the dry fabric (OI)_o and the temperature of the zenith of the first exothermic peak for the FR cotton fabrics as determined by differential thermal analysis. OI–MC relations for wool fabric and wool treated with an FR are similar to those found for the cotton fabrics except that the slopes of the lines found for the wool samples are lower than those of the equivalent cotton samples. The relation reported by Van Krevelen between OI and char residue for polymeric materials is tested for both the cotton and wool samples. Agreement with Van Krevelen's relation is not good when (OI)_o values are used. Better agreement can be obtained if OIs are determined on samples with MCs between 2 and 10%.     

The persistence of burning of textiles in different oxygen environments and the determination of the extinction oxygen index

The influence that oxygen has on the burning behaviour of cotton single- and multilayered fabries has been determined by recording persistence of burning times as a function of oxygen concentration. For a given fabric subjected to a specified igniter application time, an extinction oxygen index parameter, EOI, may be determined. EOI is defined as the oxygen concentration expressed as a volume fraction in an oxygen-nitrogen mixture, necessary to give a persistence of burning time equal to zero. For a given fabric, EOI is found to decrease as the igniter application time increases and two limiting EOI values may be observed, one corresponding to zero inginter application conditions and one for igniter application times greater than 10 s. At any given ignition time, the extinction oxygen index increases linearly with fabric area density and decreases linearly with the logarithm of the respective air permeability. Similar results are observed for nylon 6.6 and polyester single- and multilayered fabrics. The validity of the extinction oxygen index is discussed with reference to other published works.     

Thermal analysis of different cellulosic fabrics

Thermal behavior of different cellolusic fabrics was investigated in air and nitrogen by TG, DTG and DTA. Kinetic parameters based on weight loss for the initial and major stages of thermal degradation were determined. The weight loss in the TG curve for the cellulosic fabrics can be divided into four stages. In general, E_a values in air are lower than those in nitrogen, and the enthalpy changes as well as rates of degradation in air are much larger than those in nitrogen. This indicates that the thermal degradation of cellulosic fabric is promoted by oxygen. The E_a values of regenerated cellulose fabrics (viscose and modal) at the rapid weight loss stage are relatively higher than those of the cotton and linen fabrics. The raw cotton has the lowest E_a of all cellulosic fabrics, but its frequency factor and rate of weight loss are also the lowest. The thermal behavior of linen is similar to that of the raw cotton. Bleached, boiled and antibacterially finished cotton fabrics are also compared. Thermal behavior and kinetic parameters for the different cellulosic fabrics are discussed in the light of their structural characteristics, including degree of polymerization, crystallinity, crystalline form, orientation and morphology. Also the effects of the impurities and additives on the fabric are considered. © 1996 John Wiley & Sons, Inc.     

(Z,E)-α-farnesene: Major component of secretion from metathoracic scent gland of cotton seed bug,Oxycarenus hyalinipennis (Costa) (Heteroptera; Lygaeidae)

The isolation and identification of (Z,E)--farnesene[(3Z, 6E)-3,7,11-trimethyldodeca-1,3,6,10-tetraene] (III) as the major component of the secretion from the metathoracic scent gland of the cotton seed bug,Oxycarenus hyalinipennis, is reported. The compound was identified by a combination of [1H] NMR, [¹³C] NMR, UV, and mass spectral data and by comparison with a synthetic sample, prepared by dehydration of (E)-nerolidol. (Z,E)--Farnesene (III) has been recorded previously in insects (ants and termites), but this is the first report of its occurrence in a member of the Heteroptera. (E)2-Octenyl acetate (XIII) and 2-octenal (XIV) were identified as minor components of the secretion. In addition, three minor monoterpenoid and two other sesquiterpenoid components were detected and tentatively identified.     

Flame‐retardant finishing in cotton fabrics using zinc oxide co‐catalyst

In this article, N‐Methylol dimethylphosphonopropionamide (FR) in combination with a melamine resin (CL), phosphoric acid (PA) catalyst and zinc oxide (ZnO) or nano‐ZnO co‐catalyst were used (FR‐CL‐PA‐ZnO or nano‐ZnO system) to impart flame‐retardant property on cotton fabrics. FR‐CL or FR‐CL‐PA‐treated cotton specimen showed roughened and wrinkled fabric surface morphology, which was caused by the attack of the FR with slightly acidity. In addition, FTIR analysis showed some new characteristic peaks, carbonyl, CH₂ rocking and CH₃ asymmetric and CH₂ symmetric stretching bands, in the chemical structure of treated cotton specimens. Apart from these, the flame ignited on the flame‐retardant‐treated fabrics (without subjected to any post‐wet treatment) extinguished right after the removal of ignition source. However, FR‐CL treated specimens were no longer flame‐resistant when the specimens subjected to neutralization and/or home laundering, while FR‐CL‐PA treated specimens showed opposite results. By using 0.2% and 0.4% of ZnO or nano‐ZnO as co‐catalyst, the flame spread rate of neutralized and/or laundered test specimens decreased, even the specimens were undergone 10 home laundering cycles. Moreover, flame‐retardant‐treated cotton specimens had low breaking load and tearing strength resulting from side effects of the crosslinking agent used, while addition of ZnO or nano‐ZnO co‐catalyst could compensates for the reduction. Furthermore, the free formaldehyde content was dropped when ZnO and nano‐ZnO co‐catalyst was added in the treatment. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Experimental study on fire hazard of typical curtain materials in ISO 9705 fire test room

Curtain materials are commonly used as decoration, shade, or screen. They are flammable and are usually across a large part of a room, leading to the risk of a high fire hazard. Once ignited, the upward fire spread would accelerate the fire development in an enclosure. In this paper, fire hazard of three typical curtain materials with different pleat rates were tested in an ISO 9705 fire test room. Fire parameters such as temperature field, flame spread rate, heat release rate (HRR), and emitted gases, and the influences of pleat rate and cotton content on flame spread rate were investigated. The correlation between flame spread rate and HRR was discussed. The results show that the upward flame spread has an accelerating rate, and an inverted‐triangle burning area would emerge during the combustion. Some horizontal fibrillar structures appear in this burning area. Pleat rate and cotton content have considerable influence on the curtain fire behavior. The flame spread rate shows a linear response to HRR at the early stage. In addition, a function between average flame spread rate and pleat rate for engineering estimation is proposed, and a linear relationship between HRR/m_CO and m/m_CO has been obtained. The study results provide valuable reference to building fire simulation and safety design. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of a novel triazine flame retardant containing sulfur and its application to cotton fabrics

A novel triazine flame retardant (FR) has been successfully synthesized by the reaction of cyanuric chloride with sodium sulfanilate followed by diethanol amine. Its structure has been fully characterized by IR and ¹H NMR spectroscopy. The effects of reaction solvent, acid-binding agent, reaction temperature, and molar ratio of starting materials on the yield of FR were investigated in detail. Experiments showed that when the molar ratio of intermediate I to diethanol amine is 1 to 1.2 in the presence of sodium carbonate as acid-binding agent in acetone-water at 45 °C, the yield of the obtained FR reaches 81.4%. Thermogravimetry (TG) test indicated that the FR has good thermostability and char-forming ability. In addition, the flame retardancy and thermal behavior of the cotton fabrics treated with FR were studied by limiting oxygen index (LOI), vertical flammability test, and thermogravimetry (TG) to evaluate the flameretardant performance of the target FR. These results demonstrated that the flame retardancy and thermal stability of the cotton fabrics treated with FR were clearly improved.     

Kinetic studies of crease‐resistant finishing process for cotton fabrics with DMEU/MMEU prepolymer mixture

The kinetics of the crease‐resistant finishing process for cotton fabrics with DMEU/MMEU prepolymer mixture are studied. The DMEU/MMEU prepolymer resin is made from ethylene urea (EU) and paraformaldehyde (PF) with different mole ratios. The results show that the nitrogen content in the treated fabrics and the reaction rate constant increases with curing temperature and PF mole ratio. The treated fabrics with more PF in the source material have smaller E_a, Δ H*ast;, and ΔS*. The ΔG* was independent of the mole ratio in the source material, but it increases with curing temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 509–513, 2002     

Ignition temperature of coal. 1. Influence of the coal’s composition,structure, and properties

The reactions of coal with the materials used in determining the ignition temperature of unoxidized coal according to Ukrainian State Standard DSTU 7611:2014 are analyzed. First, the ignition temperature of various types of coal from Ukraine, Russia, Canada, Australia, the Czech Republic, Poland, and Indonesia is determined. The influence of the composition, structure, and properties of the coal on its ignition temperature is assessed. The ignition temperature of the unoxidized coal is found to be closely related to the content of organic carbon C^daf and aromatic carbon C_ar, the structural parameter δ characterizing the degree of saturation of the coal’s organic mass, and also the vitrinite reflection coefficient R_o and the yield of volatiles V^daf.     

Sex pheromone biosynthesis of (E,E)-8,10-dodecadienol in codling mothCydia pomonella involvesE9 desaturation

Sex pheromone biosynthesis in the codling mothCydia pomonella (Lepidoptera; Tortricidae) was studied by topical application of deuterated fatty acids in DMSO to pheromone glands. The incorporation of deuterium label into fatty acids and alcohols in the pheromone gland was monitored by gas chromatography with flame ionization detection and mass spectrometry in the selected ion monitoring mode. Dodecanol, (E)-9-dodecenol, (E,E)-8,10-dodecadienol, tetradecanol, and hexadecanol were found in gland extracts. The application of [12,12,12-²H₃]dodecanoic acid resulted in labeled dodecanol, (E)-9-dodecenol, and (E,E)-8,10-dodecadienol, as well as the corresponding labeled acids. No label was incorporated into tetradecanol or hexadecanol or any acid with more than 12 carbon atoms. The application of labeled tetradecanoic or hexadecanoic acid introduced label not only into the 12-carbon alcohols, but also into tetradecanol, or tetradecanol and hexadecanol, respectively. The application of (E)-[11, 11,12,12,12,-²H₅]9-dodecen-oic acid, whose facile synthesis is described, resulted in labeled (E)-9-do-decenol and (E,E)-8,10-dodecadienol. The (E,E)-8,10-dodecadienol so produced was characterized by an ion atm/z 186, equivalent to [M]⁺ of a dienol labeled with four deuterons. Thus, one deuterium label is lost when the labeled (E)-9-monoene is converted to the (E,E)-8,10-diene. We conclude that (E,E)-8,10-dodecadienol is synthesized by chain shortening (-oxidation) of palmitic acid to dodecanoic acid, followed by an unusualE9 desaturation and subsequent conversion of this intermediate into the conjugated precursor, which is finally reduced to the pheromone alcohol. The evolutionary significance ofE9 desaturation being responsible for pheromone production in an Olethreutinae species is discussed.     

Effect of physical aging on tensile stress relaxation and tensile creep of cured EPON 828/epoxy adhesives in the linear viscoelastic region

The effect of physical aging on viscoelastic properties was studied for several cross-linked epoxies in the glassy state. Tensile creep and tensile stress relaxation were measured during isothermal physical aging, following rapid quenching of samples annealed above the glass-transition temperature (T^g). The momentary creep curves measured at 21°C, 45°C, and 61°C below T^g for different epoxies could be fitted to an empirical equation for the creep compliance D(t): Values for β and t_o were obtained, and the dependence of t_o on the aging time was determined. Shift factors were calculated to investigate changes in molecular mobility during physical aging. The momentary stress relaxation was measured on the same epoxy materials as used for the creep studies. The stress relaxation curves were fitted to the following equation for the tensile modulus E(t): Values for α and t_o were obtained. The influence of physical aging on-t_o was again studied by calculating shift factors as a function of the aging time. The results are compared with the results of the creep tests and discussed in the context of current molecular theories of physical aging of glassy polymers.     

Mechanisms of electroless metal plating. III. Mixed potential theory and the interdependence of partial reactions

Electroless plating reactions are classified according to four overall reaction schemes in which each partial reaction is either under diffusion control or electrochemical control. The theory of a technique based on the observation of the mixed potential as a function of agitation, concentration of the reducing agent and concentration of metal ions is presented. Using this technique it is shown that in electroless copper plating the copper deposition reaction is diffusion-controlled while the formaldehyde decomposition reaction is activation-controlled. Values of the kinetic and mechanistic parameters for the partial reactions obtained by this method and by other electrochemical methods indicate that the two partial reactions are not independent of each other.Nomenclature a Tafel slope intercept - A electrode area - b _M Tafel slope for cathodic partial reaction - b _R Tafel slope for anodic partial reaction - B _M diffusion parameter for CuEDTA^2– complex - diffusion parameter for dissolved oxygen - B _R diffusion parameter for HCHO - C _M bulk concentration of copper ions - bulk concentration of dissolved oxygen - C _R ^a surface concentration of HCHO - C _R bulk concentration of HCHO - D _R diffusion coefficient of HCHO - E electrode potential - E _M thermodynamic reversible potential for the metal deposition reaction - E _M ⁰ standard electrode potential for copper deposition - E _MP mixed potential - E _R thermodynamic reversible potential for reducing agent reaction - E _R ⁰ standard electrode potential for HCHO - F Faraday constant - i _M current density for metal deposition - i _M total cathodic current density - i _M ^k kinetic controlled current density for metal deposition - i _M ⁰ exchange current density for metal deposition - i _M ^D diffusion-limited current density for metal deposition - i _M ^D diffusion-limited current density for total cathodic reactions - current density for oxygen reduction - i _plat plating current density - i _R current density for HCHO oxidation - i _R ⁰ exchange current density for HCHO oxidation - i _R ^D diffusion-limited current density for HCHO oxidation - n _M number of electrons transferred in metal deposition reaction - n _R number of electrons transferred in the HCHO oxidation reaction - R gas constant - T absolute temperature - stoichiometric number - _M transfer coefficient for metal deposition - _R transfer coefficient for HCHO oxidation - _M symmetry factor - number of steps prior to rate determining step - _M overpotential for metal deposition - _R overpotential for HCHO oxidation - v kinematic viscosity - rotation rate of electrode     

Influence of the temperature dependence of the thermophysical properties of coal–water fuel on the conditions and characteristics of ignition

The results of an experimental study and mathematical simulation of the ignition of coal–water fuel (CWF) particles, the main thermophysical characteristics of which (thermal conductivity (λ), heat capacity (C), and density (ρ)) depend on temperature, are reported. Based on the results of the numerical study, the influence of changes in the thermophysical properties upon the heating of the main bed of fuel on the conditions and characteristics of its ignition was analyzed. The ignition delay times (t _i) of CWF particles were determined under the typical furnace conditions of boiler aggregates. As a result of the mathematical simulation of the process of CWF ignition, it was established that the temperature dependence of thermophysical characteristics can exert a considerable effect on the characteristics and conditions of ignition. In this case, it was found that the ignition of coal–water drops is possible under the conditions of their incomplete dehydration. A good agreement of the theoretical ignition delay times of the CWF particles and the experimental values of t _i was established.