Differential thermal analysis of polyester/cotton blends treated with Thpc—urea—poly(vinyl bromide)

Differential thermal analyses (DTA) were made on a series of polyester/cotton blend fabrics before and after treatment with Thpc—urea—poly(vinyl bromide). This flame retardant did not affect the polyester melting endotherm, which was proportional to the polyester content and appeared at approximately 250°C. In nitrogen atmosphere, DTA of the treated blends showed exothermic peaks at 285°C for the cotton decomposition. and at 415°C for the polyester decomposition. In air, DTA of the treated blends showed exothermic peaks at 333°C for cellulose decomposition, at 431°C for polyester decomposition and at 490°C for char decomposition. The Thpc-urea component of the flame retardant is effective on the cotton cellulose portion of the blend; the poly(vinyl bromide) appears to decompose and act in the vapor state on the polyester.     

Synthesis and characterization of a novel phosphorus–nitrogen‐containing flame retardant and its application for textile

The economic and environmentally friendly flame‐retardant compound, tetramethyl (6‐chloro‐1,3,5‐triazine‐2,4‐diyl)bis(oxy)bis(methylene) diphosphonate ( CN‐1 ), was synthesized by a simple two‐step procedure from dimethyl phosphate, and its chemical structure was characterized by ¹H, ¹³C, and ³¹P nuclear magnetic resonance and gas chromatography mass spectroscopy. Using the traditional pad–dry–cure method, we obtained several different add‐ons (wt%) by treating cotton twill fabric with flame retardant ( CN‐1 ). Thermogravimetric analysis, in an air and nitrogen atmosphere, of the modified cotton showed that decomposition occurred ~230°C with 16% residue weight char yield at 600°C, indicating high thermal stability for all treated levels. Limiting oxygen index (LOI) and the vertical flammability test were employed to determine the effectiveness of the flame‐retardant treatments on the fabrics. LOI values increased from ~18 vol% oxygen in nitrogen for untreated fabric to maximum of 34 vol% for the highest treatment level. Fabrics with higher levels of flame retardant also easily passed the vertical flammability test. Furthermore, Fourier transform infrared and scanning electron microscopy were utilized to characterize the chemical structure as well as the surface morphology of the flame‐retardant treated twill fabrics, including char area and the edge between unburned fabric and char area. Copyright © 2011 John Wiley & Sons, Ltd.     

Thermogravimetric analysis of aluminised E-glass fibre reinforced unsaturated polyester composites

Novel aluminised E-glass fibre reinforced unsaturated polyester composites, originally formulated for enhanced thermal and electrical shielding properties were evaluated in terms of their thermal performance. The thermal degradation of these specimens was analysed using a thermogravimetric analyser (TGA). The samples were heated from ambient temperature to 500 °C at a heating rate of 20 °C/min. All specimens were decomposed under dry nitrogen (N₂) at a flow rate of 40 ml/min to yield gases and solid char. Aluminised E-glass composites were compared alongside the unmetallised E-glass and unreinforced composite. The major weight loss occurred between 200 and 400 °C. The unreinforced polyester had a maximum weight loss, 1.25%/°C, occurring at 360 °C. For the aluminised and unmetallised E-glass composites, the maximum rate of weight loss was 0.34 and 0.55%/°C, respectively. Experimental results show the degradation of the aluminised E-glass composites obtained from TGA tests is higher compared to those of unmetallised E-glass fibre and unreinforced polyester composite. This improvement is correlated to the aluminium coating.     

Thermoanalytical studies of flame-retardant polyester/ cotton textile blends: a comparison of THPC-urea-PVBr and THPOH ammonia treatments

Flame-retardant polyester/cotton fabrics are increasing in importance in the apparel and household fabrics market. Phosphorus-nitrogen flame-retardant systems developed for 100% cotton are not necessarily effective for polyester/cotton blends. Bromine effectively imparts flame-retardant properties of polyester resins. It has been theorized that systems containing both bromine and phosphorus should be suitable for polyester/cotton blends. A thermoanalytical study was undertaken to elucidate the effect of bromine in flame-retardant polyester/cotton blend fabrics. Fabrics having various ratios of polyester to cotton were treated with THPOH---NH₃, which is particularly effective on 100% cotton, and with THPC-urea-PVBr, which was designed for 50/50 polyester/cotton blends. For comparison, data are also presented on a 50/50 polyester blend fabric treated with THPOH---NH₃ and with THPC—urea flame retardants plus tris(2,3-dibromopropyl) phosphate in a two-step application. TG and DSC data were obtained in atmospheres of either nitrogen or air, using a DuPont 990 Thermal Analysis System². The thermal changes are assigned to decompositions of cotton, polyester, char, and resin finish. A comparison is made of the effects caused by the different flame-retardant finishes. Ol values and FF 3-71 data are reported.     

Catalytic pyrolysis of Phragmites (reed): Investigation of its potential as a biomass feedstock

In this paper, thermogravimetry, TG, and pyrolysis are used for the thermochemical evaluation of the common reed (Pragmites australis) as a candidate biomass feedstock. The TG analysis indicated that the material loses 4% of its weight below 150 °C through dehydration. The main decomposition reaction occurs between 200 and 390 °C. The rate of weight loss, represented by the derivative thermogravimetric, DTG, signal indicated a multi-step reaction. Kinetic analysis helped in the resolution of the temperature ranges of the overlapping steps. The first step corresponds to the degradation of the hemi-cellulosic fraction and the second to the cellulosic fraction degradation. The TG and DTG signals of reed samples treated with increasing concentration of potassium carbonate (0.6–10 wt%) indicated a catalytic effect of the salt on reed decomposition. The temperature of maximum weight loss rate, DTGmax, exponentially decreased with increasing catalyst content, whilst the initial temperature of the decomposition decreased linearly. The pyrolysis studies were carried out in a Pyrex vertical reactor with sintered glass disc to hold the sample and to aid the fluidization with the nitrogen stream flowing upwards. The reactor was connected to a cyclone and condenser and a gas sampling device. Tar and char are collected and weighed. The gas chromatographic analysis of the evolved gases demonstrated the effect of pyrolysis temperature (400, 450, and 500 °C) on their composition. The temperature increase favors the yields of hydrocarbons, carbon monoxide and hydrogen at the expense of methanol and carbon dioxide. Similarly, reed samples treated with K2CO3 at 10 wt% were pyrolyzed and analyzed. Comparisons for the various parameters (yields, gas composition and carbon–hydrogen recovery) between the untreated and catalyzed reed conversion were also made.     

Synthesis and Characterization of Soluble Polyester Based on Calixarene Dicarboxylic Acid with Tertiary Butyl Pendant Groups

A series of new polycalixesters(PCES) were synthesized by polyesterification of calixarene dicarboxylic acid derivatives having tertiary butyl pendant groups at the upper rim using five different diols. All polyesters were readily soluble in polar solvents such as NMP(N-methylpyrrolidone), DMF(dimethylformamide), DMSO(dimethylsulfoxide), pyridine, THF(tetrahydrofurane), HMPA(hexamethylenephosphoramide) and DMAC(dimethylacetamide). The PCES were also partially soluble in TCE(tetrachloroethane) and ethanol and they were unsoluble in aceton. The glass transition temperatures of polyesters were between 80-184 °C, the crystallinity temperatures of polyesters were between 130–212 °C and the melting temperatures of polyesters were between 185–234 °C, as determined by differential scanning calorimeter(DSC). The inherent viscosities of polyesters were obtained from 0.55 dL/mg to 0.61 dL/mg. The temperatures at 10% weight loss of polyesters ranged from 182 °C to 237 °C. The temperatures at 25% weight loss of polyesters ranged from 258 °C to 331 °C. The half weight loss(50%) temperatures of polyesters were among 315 °C to 371 °C and the char yields at 600 °C were determined within 13% to 22.3% in N2 atmosphere, as determined by thermo gravimetric analysis(TGA). The polyester, PES3, has the higher melting point(234 °C) and higher inherent viscosity(molecular weight) than the other polyesters.     

High-temperature gasification kinetics of biomass pyrolysis

The rate of gas formation from wood pyrolysis has been experimentally measured at temperatures from 300°C to 1000°C. The formation rate of specific product gases has been measured rather than the rate of solid weight loss. Even for very fine particles, the rate becomes heat transfer limited a: high temperatures. The product gases also approach thermodynamic equilibrium rapidly at high temperatures. The results are corrected using the experimental residence time distribution.     

Ultrasound-assisted ozone bleaching of cotton

In this study, the effects of ultrasound on ozone treatment processes for bleaching cotton fabrics were investigated and compared with the conventional hydrogen peroxide bleaching process (60 °C over 90 min). Two ultrasonic + ozone treatments of cotton fabric samples were carried out: (1) ozone in an ultrasonic homogenizer (UH) and (2) ozone in an ultrasonic bath. Ozone dosages, temperature and time variations were determined with both ozone-ultrasonic bleaching processes. Whiteness, yellowness, weight, tensile strength properties, FTIR (ATR) spectra and visual appearance, via scanning electron microscopy of treated cotton fabrics as well as chemical oxygen demand (COD) of bleaching effluents, were investigated. It was concluded that the ozone + UH process, conducted for 30 min at 30 °C, produced closely equivalent values of cotton fabric whiteness and yellowness to the classic peroxide bleaching process, with slightly less weight loss, dramatically less COD in the process effluent (29 mg/l for ozone-UH vs. 4,316 mg/l for classical peroxide treatment), and without causing any adverse and/or detrimental effects on loss of fabric strength or elongation of the cotton fabrics. The ozone-UH process also leads to time and energy savings with much less environmental impact. Consequently, the combination of ozonation plus UH carried out at 30 °C over 30 min can be used successfully for cotton bleaching instead of the classic hydrogen peroxide bleaching process.     

Syngas Production from Lignite Coal Using K2CO3 Catalytic Steam Gasification with Controlled Heating Rate in Pyrolysis Step

Gasification uses steam increases H2 content in the syngas. Kinetics of gasification process can be improved by using K₂CO₃ catalyst. Controlled heating rate in pyrolysis step determines the pore size of charcoal that affects yield gas and H₂ and CO content in the syngas. In previous research, pyrolisis step was performed without considering heating rate in pyrolysis step. This experiment was performed by catalytic steam gasification using lignite char from pyrolysis with controlled heating rate intended to produce maximum yield of syngas with mole ratio of H₂/CO ≈ 2. Slow heating rate (3 °C/min) until 850 °C in the pyrolysis step has resulted in largest surface area of char. This study was performed by feeding Indonesian lignite char particles and K₂CO₃ catalyst into a fixed bed reactor with variation of steam/char mole ratio (2.2; 2.9; 4.0) and gasification temperature (750 °C, 825 °C, and 900 °C). Highest ratio of H₂/CO (1.682) was obtained at 750 °C and steam/char ratio 2.2. Largest gas yield obtained from this study was 0.504 mol/g of char at 900 °C and steam/char ratio 2.9. Optimum condition for syngas production was at 750 °C and steam/char mole ratio 2.2 with gas yield 0.353 mol/g of char and H₂/CO ratio 1.682.     

Effect of urea additive on the thermal decomposition of greige cotton nonwoven fabric treated with diammonium phosphate

This study showed that greige cotton nonwoven fabric can effectively be flame retardant by applying the phosphorus of diammonium phosphate (DAP) as low as 0.8 wt% with the addition of urea. At such a low content of phosphorus, the char length and limiting oxygen index (LOI) were continuously decreased and increased, respectively, as the concentration of urea increased. The effect of urea additive on the thermal decomposition of flame retardant greige cotton nonwoven fabric was investigated by thermogravimetry, ATR-FTIR, XRD, ¹H → ¹³C CP/MAS NMR, and SEM. The results indicated that, upon heating, urea not only facilitated the phosphorylation reaction of DAP but also introduced carbamate groups into cellulose to decrease the degree of crystallinity prior to the decomposition of the crystalline cellulose. Compared with DAP treatment alone, the addition of urea accelerated the decomposition of glycosyl units, which resulted in a slight increase of weight loss and decrease of char yield. The char morphology observed after LOI tests indicates that urea released nonflammable gases, which blew the carboneous char layer to protect the underlying substrate.     

THERMAL DEGRADATION KINETICS OF THERMOTROPIC COPOLY (P-OXYBENZOATE-ETHYLENE TEREPHTHALATE-VANILLATE) BY A HIGH-RESOLUTION THERMOGRAVIMETRY

Thermotropic liquid crystalline terpolymers consisting of three units of p-oxybenzoate (B), ethylene terephthalate (E), and vanillate (V), were studied through a high-resolution thermogravimetry to ascertain their thermostability and kinetics parameters of thermal decomposition in nitrogen and air. Overall activation energy data of the major decomposition have been calculated through four calculating techniques. The thermal degradation occurs in three steps in nitrogen, but in four steps in air due to an additional thermo-oxidative step. The thermal degradation temperatures are higher than 436°C in nitrogen and 424°C in air and increase with increasing B-unit content at a fixed V-unit content of 5 mol%. The temperatures at the first maximum weight-loss rate are higher than 444°C in nitrogen and 431°C in air and increase slightly with an increase in B-unit content. The first, second, and third maximum weight-loss rates almost maintain at 10–11, 10–11, and 3.6–5.3%/min regardless of copolymer composition and testing atmosphere. The char yields at 500°C in both nitrogen and air are larger than 40 wt% and increases with increasing B-unit content. But the char yields at 800°C in nitrogen and air are quite different, i.e., 18–25 wt% in nitrogen and 0 wt% in air. The activation energy and Ln (pre-exponential factor) for the major decomposition are higher in nitrogen than in air and decrease slightly with an increase in B-unit content at a given V-unit content 5 mol%. There is no regular variation in the decomposition order with the variation of copolymer composition and testing atmosphere. It is found that the most V-unit-containing terpolymer exhibited the lowest degradation temperature, lowest activation energy, and lowest Ln (pre-exponential factor). The activation energy, decomposition order, and Ln (pre-exponential factor) of the thermal degradation for the terpolymers, are situated in the ranges of 121–248 kJ/mol, 1.5–2.8, 19–38 min^?1, respectively. These results indicate that the terpolymers exhibit high thermostability. The isothermal decomposition kinetics of the terpolymer at 450°C have also been discussed and compared with the results obtained based non-isothermal high-resolution thermogravimetry.     

Pyrolysis of sweet orange (Citrus sinensis) dry peel

Three different products were obtained from the pyrolysis of dry peel sweet orange: bio-oil, char and non-condensable gases. The yield of each product was determined. The bio-oil was characterized by GC–MS to determine that can be used as a renewable source of valuable industrial chemicals or as a source of energy, high heating value was calculated by Channiwala and Parikh correlation based on Dulong's Formula.Thermogravimetric analysis at 1, 5, 10, 20, and 40 °C/min, shows three different overlapped steps resulting in an average mass loss of ∼80% within the temperature range of 114–569 °C. The bench scale pyrolysis experiments, produces average yields of 53.1, 21.1 and 25.8 wt.% for bio-oil, char and gases, respectively. Bio-oil characterization by GC–MS and FTIR identified limonene as its main component while other identified compounds included δ-limonene, alcohols, phenols, benzene, toluene, xylene and carboxylic acids.     

碱处理条件下涤/棉织物的减量变化

对涤棉混纺织物进行碱处理,讨论了NaOH用量、温度、时间对涤棉混纺织物性能的影响,并与纯棉织物和纯涤纶织物的碱处理结果进行对比。结果表明,NaOH用量对织物的失重率影响最大,且纯涤纶的失重率和失重速率都明显高于涤棉混纺织物;在常压下,碱处理对棉的影响很小。     

Study on the gas evolution and char structural change during pyrolysis of cotton stalk

The gas release properties and char structural evolution during the pyrolysis of cotton stalk were investigated. The evolution characteristics of volatile products were examined by pyrolysis–Fourier transform infrared spectroscopy (FTIR)/thermal conductivity detection (TCD) analysis (Py–FTIR/TCD). The char chemical structure and physical characteristics were investigated by means of FTIR and N₂ physisorption techniques. Evolution characteristics of the main volatile products were given. The evolution of CO₂ was approximately 26 °C earlier than that of CO. CH₄ evolution covered over a wider temperature range of 300–600 °C, with a maximum at 394 °C. The amount of hydroxyl, aliphatic CH and olefinic CC bonds in the char decreased significantly above 250 °C. The aromatization process started at ≈350 °C and continued to higher temperatures, leaving the char enriched with condensed aromatic ring systems. The BET surface area increased continually with increasing temperature to reach a maximum value of 4.68 m²/g at 500 °C and decreased at higher temperatures. The micropore volume showed a similar behavior to the surface area, while the mesopore volume and total pore volume always increased.     

升温速率对胜利褐煤热解过程中N迁移转化的影响

在固定床/流化床管式石英反应器中进行了胜利褐煤的快速热解和慢速热解实验,考察了升温速率对N迁移转化及对半焦内部N化学形态变化的影响。研究结果表明,快速升温热解气相N(NH₃和HCN)生成量明显高于慢速热解时的生成量,且随着温度的升高,两者差值均逐渐增大。在多数情况下,NH₃或HCN的产率在973 K左右并不随温度的升高而增加,这与高温下的半焦热缩聚反应以及挥发分的二次反应有关。快速热解条件下,半焦N的释放速率要快于半焦炭本身失重速率。X射线光电子能谱(XPS)分析认为,热解使得吡咯型N(N-5)部分转化为吡啶型N(N-6)和季氮型N(N-Q),快速热解有利于生成N-6,而慢速热解下半焦中N-Q含量较高。     

Study of carbon black obtained by pyrolysis of waste scrap tyres

Waste scrap tyres were thermally decomposed under various conditions. Decompositions were followed by the TGA method. Specific heating regimes were tested to obtain optimal structural properties of resulting pyrolytic carbon black produced by pyrolysis of scrap tyres and the process was characterized in temperature interval from 380 to 1,200 °C and heating rate 10, 20 and 50 °C min^?1 under nitrogen atmosphere. The original scrap tyres and pyrolytic carbon black were characterized by Raman and Fourier transform infrared spectroscopy methods. Textural properties were also determined. Effect of temperature and heating rate on process of pyrolysis of scrap tyres was observed. Shifting of temperature of maximum pyrolysis rate to lower value and spreading of DTG peak is caused by increasing heating rate. Temperature 570 °C was sufficient for total scrap tyres pyrolysis. Graphitic and disordered structure was distinguished in the formed carbon black by Raman spectroscopy. With increasing temperature, heating rate and weight loss, the amount of the graphitic structure was reduced at the expense of disordered structure. Destruction of nonporous scrap tyres and formation of porous structure took place at higher temperature. Porous carbon black is formed above 380 °C, specific surface area increased up to 88 m² g^?1 .     

The application of thermal analysis to the combustion of cellulose

It is shown that the use of differential thermal analysis (DTA) to follow the pyrolysis of cellulose in air products two and sometimes three exothermic peaks. The first peak is associated with the combustion of volatile material, released in the degradation process, the second is caused by the glowing combustion of the carbonaceous residue, and the final exotherm is probably due to the combustion of product gases.The thermogravimetric analysis (TG) data in air show a preliminary loss of water followed by a mass loss of about 85% due to the production of the combustible volatiles. This second step appears identical to the degradation process in nitrogen, but in air the degradation products ignite to produce the first exothermic peak on the DTA. The glowing combustion DTA peak is associated with a further mass loss of about 15% on the TG plot. The use of a thermomechanical analyser shows that a small shrinkage of 3% occurs between 45 and 110°C, with the major collapse taking place between 300 and 370°C. There is, however, an expansion of 10% between 370 and 405°C, believed to be due to a crosslinking reaction.     

Layer-by-layer assembled thin films based on fully biobased polysaccharides: chitosan and phosphorylated cellulose for flame-retardant cotton fabric

Polyelectrolytes multilayer (PEM) films based on fully biobased polysaccharides, chitosan and phosphorylated cellulose (PCL) were deposited on the surface of cotton fabric by the layer-by-layer assembly method. Altering the concentration of PCL could modify the final loading on the surface of cotton fabrics. A higher PCL concentration (2 wt%) could result in more loading. Attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis directly showed that chitosan and PCL were successfully deposited onto the surface of cotton fabric. In the vertical flame test, the cotton fabric with 20 bilayers at the higher PCL concentration (2 wt%) could extinguish the flame. Microcombustion calorimetry results showed that all coated cotton fabrics reduced the peak heat release rate (HRR) and total heat release (THR) relative to the pure one, especially for (CH0.5/PCL2)₂₀, which showed the greatest reduction in peak HRR and THR. Thermogravimetric analysis results showed that the char residue at temperatures ranging from 400 to 700 °C was enhanced compared to that in the pure cotton fabric, especially in the case of higher PCL concentration (2 wt%). The work first provided a PEM film based on fully biobased polysaccharide, chitosan and PCL on cotton fabric to enhance its flame retardancy and thermal stability via the layer-by-layer assembly method.     

Upgrading of woody biomass by torrefaction under pressure

In this study, the upgrading by torrefaction of leucaena, woody biomass, at 200–250 °C under volumetric pressure up to 4 MPa was examined. It was found that the yield of torrefied leucaena decreased with the increase in torrefaction temperature, whereas at the same temperature the yield of torrefied leucaena increased with the increase in torrefaction pressure. From the elemental analyses, the higher carbon content in torrefied leucaena can be achieved by the rising of torrefaction pressure. As large as 92.6% of carbon was recovered in the torrefied leucaena prepared at 250 °C and 4 MPa. On the other hand, the oxygen content decreased to 31.1% for the leucaena torrefied at 250 °C and 4 MPa. The higher heating value (HHV) of leucaena torrefied at high pressure increased significantly when compared to that of leucaena torrefied at atmospheric pressure. As large as 94.3% of energy yield was achieved with the mass yield of 74.4% for the torrefaction at 250 °C and 4 MPa. From the subsequent pyrolysis and combustion in TGA, leucaena torrefied under pressure showed the difference of weight decreasing curves comparing to that of leucaena torrefied at atmospheric pressure. It was found that the weight of leucaena torrefied at high pressure started to decrease at temperature lower than 200 °C. The char yield at 800 °C for the leucaena torrefied at high pressure increased with the increase in torrefaction pressure. These results suggested that the structure of leucaena was changed by the torrefaction under pressure and the cross-linking reactions during the pyrolysis were enhanced by the pressure during the torrefaction resulting in increase in char yields. The substantial increase in char combustion rate was also found for leucaena torrefied under pressure.     

Organic–inorganic hybrid silica film coated for improving resistance to capsicum oil on natural substances through sol–gel route

This study concerns the organic–inorganic hybrid coating of silica sol based on dyed cotton, silk and wool fabrics in order to increase the repellence to capsicum oil via adding methyltriethoxysilane, octyltriethoxysilane, hexadec-ltrimethoxysilane or tridecafluorooctyltriethoxysilane (FAS) in the inorganic silica sol. The dyed cotton fabric treated with hybrid silica sol doped with FAS (F-silica sol, FAS 4 %) presents oil-repellent capability, and the contact angles of capsicum oil on the treated cotton, silk and wool fabrics are 98.5°, 111.59° and 122.15°, respectively. A high FAS concentration (20 %) can improve the oil-repellent ability to 5 grades comparing to the untreated fabrics. The color strengths (K/S) of the coated fabrics change slightly, while the maximum absorption wavelengths of the coated fabrics are the same as the untreated fabrics. Although the drape coefficient of cotton fabric is increased to 54 % from 39 % after coated with F-silica sol, the effect is not significant. Compared to the weight gain rate of untreated cotton, silk and wool samples (1.89, 1.23 and 2.38 %), the weight gain rate of the cotton, silk and wool samples coated with F-silica sol are 6.99, 4.76 and 7.69 %, respectively. The calculated sol–gel weight gains (5.10, 3.53 and 5.31 %) of coated fabrics indicate that the silica coating is subsistent on the fiber surfaces.