Decomposition Temperature Range Research Articles

Analysis of microwave heating of copper powder compacts

The influence of the native oxide films, which is essential for the understanding of the microwave heating of metal powder, is analyzed numerically based on the experimental data on temperature, dilatation and resistance of compacted copper powder samples. The indicative thickness of the oxide films, determined from the resistivity data using an effective medium approximation, is shown to decrease from ≥1 μm to below 1 nm. The effective complex dielectric permittivity and magnetic permeability of the copper powder with oxide films on the particles are calculated within the recently developed models. The dielectric permittivity exhibits a percolation behavior in the temperature range of the oxide decomposition, viz. 210–250 °C when microwave heating is carried out in nitrogen and 330–375 °C – in argon. The efficiency of absorption of the incident 30 GHz microwave radiation in a slab of powder is assessed separately for the electric and magnetic-type losses, the contribution of the latter being predominant until the percolation transition. The energy flux density of the incident microwave radiation required to sustain the prescribed heating rate is shown to increase during the microwave heating process from ∼20 W/cm2 to >1 kW/cm2 due to increasing reflection. The additional microwave energy input required for the completion of the endothermic oxide decomposition reaction is shown to be significant at the initial stage of the process (below 200 °C).

The new polycyclotriphosphazenes: Synthesis, characterization, thermal and photophysical properties

Polyamides are used as high-performance materials in industry and electronics. Researchers have recently been focusing on this area and trying to synthesize more stable and high-performance molecules by polymerizing various groups into the backbone skeleton. In this work, we report the design, synthesis, and characterization of paracetamol derivatives of cyclotriphosphazene (DSPCT and DSHY) and polycyclotriphosphazenes (DSTPC and DSAC) for the first time. The structures of new products were fully characterized by MALDI-TOF Mass analysis, FT-IR, 1H and 31P NMR spectroscopies and single crystal X-ray (for DSPCT and DSHY) crystallography. The crystallization behaviours of the polyamides were studied by X-ray diffraction, and a scanning electron microscope was used to observe the morphology of the DSTPC and DSAC. Thermal degradation properties for DSHY, DSTPC and DSAC were determined by DSC and TGA techniques. Polyamides and the DSHY compound exhibited superior thermal stability with an initial decomposition temperature range of ca. 251–302 °C. Additionally, spectral characterization and photophysical behaviours (fluorescence quantum yields and lifetimes) of the all new compounds were also comprehensively investigated using UV–Vis and fluorescence spectroscopies (steady-state and time-resolved fluorescence).

EVALUATION OF THE THERMAL-OXIDATIVE STABILITY OF A HALOGEN-CONTAINING PLASTICIZER-FIRE RETARDANT

The importance of assessing the indicators of thermal-oxidative stability of plasticizers that are part of polymer compositions for ensuring high performance indicators during their processing and operation of finished products is noted. When using brominated organic compounds of the aromatic series, a short burning time of polymer compositions and a significant smoldering time have been established. The use of flame retardants containing a halogen in the aliphatic radical leads to a decrease in the smoldering time and an increase in the duration of combustion due to a decrease in the thermal stability of the material at the stage of decomposition. It is indicated that bromine-containing compounds give the best inhibition effect compared to chlorine-containing compounds due to a decrease in the carbon-bromine bond breaking energy compared to the carbon-chlorine bond energy. The decomposition parameters of the brominated plasticizer-fire retardant have been established. It is shown that the thermal decomposition of the brominated plasticizer occurs in two stages, corresponding to the elimination of bromine from the aliphatic radical in the temperature range 473 K – 573 K and the decomposition of phthalic acid esters in the range 603 K – 623 K. The beginning of intensive decomposition corresponds to 443 K. The maximum of the first stage of decomposition is at the point corresponding to 501 K, the second - 606-623 K. It was noted that the bromine-free plasticizer decomposes intensively, starting from 503 K and reaches the maximum decomposition rate at 611 K. The maximum loss of the bromine-free plasticizer was established at 27%, brominated - 50.9% of the mass of the sample. It has been confirmed that the presence of bromine atoms in the plasticizer adversely affects its thermal stability. The influence of the degree of halogenation of an unsaturated plasticizer on the nature of its thermal-oxidative degradation in the temperature range corresponding to the technological parameters of processing polymeric materials at elevated temperatures of 413-443 K has been studied. It is shown that an increase in the content of bromine in the plasticizer when performing technological operations for the processing of polymer compositions in the specified temperature range and the duration of exposure to elevated temperatures within one hour does not significantly affect the mass fraction of bromine in the plasticizer. A kinetic equation for the reaction of thermal decomposition of a bromine-containing plasticizer-flame retardant of the phthalate type, accompanied by the elimination of hydrogen bromide, is proposed. The activation parameters of the hydrogen bromide evolution reaction were determined for the temperature range of maximum decomposition of a brominated phthalate plasticizer with a bromine content in the range of 5% – 25%. It is shown that the activation energy of hydrogen bromide elimination depends on the bromine content in the plasticizer and decreases by 23% with an increase in the degree of bromination. It is shown that the temperature range of maximum decomposition of the brominated fire retardant plasticizer, corresponding to 473 K – 573 K, allows using it as a secondary plasticizer for polyvinyl chloride without reducing the thermal stability of the base.

Inhibition of CO oxidation over Cu-Mn-Ce-O composite catalyst in the presence of dry powder fire extinguishing agent: Mechanism investigation and mitigation strategy

The effects of typical dry powder fire extinguishing agents (DPFEA) on the CO oxidation catalysts were carried out. Cu-Mn-Ce-O composite catalyst (CuMn/Ce) for CO oxidation in loose contact with two typical components of DPFEA (NH4H2PO4 and NaHCO3) was tested to evaluate the performance of CO removal. The CO catalytic activities mixed by NaHCO3 are worse than those mixed by NH4H2PO4 at the same mixing ratios, which may be caused by the lower temperature range of NaHCO3 decomposition and the masked catalyst surfaces by CO2 and H2O released by NaHCO3. Further, the NaHCO3 resistance approach was proposed by introducing rare earth metal dopants (La, Sm and Ho) or coupling an alkaline sorbent (LiOH). Among all rare earth metal dopants, Sm is most appropriate for enhanced NaHCO3 resistance of CuMn/Ce catalyst. And 20 wt% LiOH-CuMn/Ce shows the best capacity for NaHCO3 resistance, as evidenced by the excellent CO catalytic performance similar to pure CuMn/Ce.

Seville history insight through their construction mortars

Seville is intimately linked to its historic role and extensive cultural heritage. The city has been occupied by Romans, Arabs and Christians, who built important historical buildings. Roman (first–second centuries) and Arabic (eleventh century) buildings, medieval Shipyard (thirteenth century), San Isidoro and Santa Maria de las Cuevas monasteries (fifteenth century), Santa María de las Cuevas (fifteenth century modified in eighteenth century), El Salvador Church (eighteenth century), the Royal Ordnance building (eighteenth century) and Santa Angela de la Cruz convent (twentieth century) performed with lining mortars, and mortars used in building stones (City Hall and Marchena Gate), all of them located in Seville (Spain), have been studied. Ninety-four mortar samples (employed as structural, plaster, coating) originally used or applied in restoration processes have been collected to perform an archaeometry study. The ratio of CO2 mass loss to hydraulic water (H2O) mass loss, and the mineralogical characterization by X-ray diffraction has been used to compare the mortars used in the different historical periods. Mainly hydraulic mortars were widely used in all these studied monuments as most mortars showed CO2/H2O ratios within the 4–10 range. Moreover, the thermal analysis curves also showed a broad temperature range for the thermal decomposition of the carbonate fraction of the mortars.

Facile synthesis of polystyrene‐coated carbon nanotubes via microwave‐assisted in‐situ polymerization and tuning of the DC electrical conductivity and impedance characteristics

AbstractAn attempt has been made to tune the DC electrical conductivity and impedance characteristics of the nanocomposites by coating carbon nanotubes (CNTs). A microwave‐assisted in‐situ polymerization approach is utilized to coat the CNTs with polystyrene and no initiators are used. The nanocomposites are characterized by FE‐SEM, TEM, FT‐IR, Raman and TGA. Based on the morphological studies, a polystyrene layer is detected on the CNTs. According to the TGA results, the weight loss in the temperature range of polystyrene decomposition increases with increasing microwave irradiation time, suggesting a higher polystyrene content. Moreover, the DC electrical conductivity of the nanocomposites, as well as the real and imaginary impedance and dielectric permittivity are explored. It is shown that increasing the irradiation time decreases the DC electrical conductivity and dielectric permittivity but increases the real and imaginary impedance. Since the thickness of the polystyrene layer depends on the duration of microwave irradiation, our method can be used to tune the electrical conductivity and impedance characteristics. This can be applied to practical situations where a particular resistance is required.

Study on mechanical alloying behavior and thermal stability of HfMoNbTaTi refractory high-entropy alloy

The present study prepared HfMoNbTaTi refractory high-entropy alloy powders with uniform distribution of components by mechanical alloying (MA). Six scenarios were designed to investigate the effects of rotational speed, milling duration, ball-to-powder weight ratio (BPR), and process control agent (PCA) on the alloy powder to achieve complete alloying, controlled morphology, and refined grain size. Results showed that the alloying efficiency and lattice strain increased significantly while the grain size decreased with increased rotational speed and BPR. In addition, the content of impurity elements (e.g., C, O, and Fe) also increased. Stearic acid added as PCA effectively prevented cold-welding and refined the particle/grain size but led to the appearance of unknown carbides. Excellent thermal stability was provided by the mechanically alloyed powders when annealed below 1000 °C. In contrast, the single body centered cubic (BCC) solid solution structure decomposed at 1200 °C annealing, and the decomposition temperature range was 942.5 °C–1041.2 °C based on the DSC curve. Finally, the dissolution pattern of components, the size mismatches effect, impact energy, and the optimal range of mechanical alloying process parameters were discussed in detail.

Experimental and kinetic study of N2O thermal decomposition in pressurized oxy-combustion

Pressurized oxy-combustion is regarded as a promising carbon capture technology for mitigating global warming. In addition, N2O is a significant greenhouse gas in pressurized oxy-combustion at moderate temperatures, with a Global Warming Potential 310 times that of CO2. It is important to study the formation and control of N2O in pressurized oxy-combustion. In this paper, the effects of CO2 atmosphere, pressure, temperature, residence time, and O2 concentration on N2O decomposition were investigated in a pressurized plug flow reactor. The results show that CO2 atmosphere significantly promotes N2O decomposition compared to N2 atmosphere. Increasing temperature accelerates the decomposition of N2O, with 1023–1223 K being the main decomposition temperature range. The decomposition efficiency of N2O increases with increasing pressure, while its increase becomes slow at above 5 bar. N2O decomposition efficiency in CO2 atmosphere decreases slightly as O2 concentration increases. The experimental results were compared to the kinetic modeling results calculated using GRI3.0 and GLA2018 mechanism, respectively. The modeling results show that GRI3.0 mechanism accurately predicts the decomposition of N2O at 1 bar while overestimates the decomposition at elevated pressures, while GLA2018 mechanism significantly underestimates the decomposition at all tested pressures. Further Rate-of-production analysis shows that the main reaction of N2O decomposition is N2O(+M) = N2 + O + M, which becomes the dominant reaction especially at elevated pressures. An enhanced third-body efficiency of 3 for CO2 was incorporated into the reaction N2O(+M) = N2 + O(+M) in GLA2018, which could predict the decomposition of N2O at elevated pressure accurately. The above results indicate that the decomposition of N2O is significantly enhanced in pressurized oxy-combustion.

Thermal decomposition mechanism analysis of circulating solids sampled from Ende pulverized‐coal gasifier

AbstractEnde pulverized‐coal gasifier (EPCG) is a type of circulating fluidized bed gasifier, in which the circulating solids are resent into the furnace through a return conduit for regasification. Since the solid circulation in the return conduit mainly relies on gravity self‐balancing, it is easy to cause low and unstable solid circulation rate and increase unburned combustible of fly ash. To solve these problems, a circulation enhancement technique using an ejector to provide a stable pressure barrier to promote solid circulation was proposed. To verify its feasibility, considering that the circulating solid‐CO2 reaction is a rate‐controlling step in the gasification process, it is of great significance to explore the reactivity characteristics of the circulating solids under CO2 atmosphere. In this work, thermal decomposition characteristics of Hailar circulating solids (HLE‐CS), Hailar char (HLE‐C), and Shenhua circulating solids (SH‐CS) were investigated by non‐isothermal thermogravimetric analysis to compare the gasification reaction characteristics of circulating solids and char. The HLE‐CS and SH‐CS used in the experiments were taken from the return conduit of 45,000 and 20,000 Nm3/h EPCGs, respectively, while HLE‐C was made from the raw coal of 45,000 Nm3/h EPCG. The effects of different samples under the same thermal decomposition temperature range were investigated. The kinetic parameters were determined by the distributed activation energy model. The results indicated that remarkable peaks were found in the relationship between temperature (T) and activation energy (E) for HLE‐CS and SH‐CS, but there was no significant peak for HLE‐C, and kinetic compensation effects also existed between ln(k0) and E for different samples. The circulating solids of HLE‐CS and SH‐CS were more easily gasified than that of HLE‐C in the lower temperature ambience. Moreover, HLE‐CS and SH‐CS have obvious pyrolysis and gasification stages, which can be completely introduced into EPCG for regasification, and increasing the circulating solid rate and temperature within a certain range is beneficial to enhance the gasification rate.

Thermal decomposition of vegetative fuels and the impact of measured variations on simulations of wildfire spread

This manuscript presents new measurement data from milligram-scale thermal decomposition experiments – thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC) – conducted on stems and leaves (i.e., needles) of six plant species commonly found across the United States. For each fuel, measurement data from TGA experiments was analyzed to determine effective thermal decomposition mechanisms and the associated kinetics of their constituent reactions. Results of this model calibration were compared to standard (i.e., ‘generalized’) approaches to obtain kinetic parameters available in the literature. MCC experiments were repeated under identical experimental conditions to determine the heats of complete combustion of all gaseous volatiles produced by these vegetative fuels and to validate the decomposition mechanisms and species char yields determined from TGA data. Through a coupled analysis of TGA and MCC measurement data, an estimate of the heats of combustion of the gaseous volatiles produced by individual reaction steps in the fuel’s decomposition was also made. Between different fuels, distinct differences were measured in the onset temperature of decomposition, the temperature range of decomposition, the number of apparent reactions, and the peak measured mass loss and heat release rates (as well as the temperatures at which they occur). To analyze the impact of these variations on predictions of wildfire behavior, a modeling study was then conducted in which simulations of wildland fire experiments were repeated using the thermal decomposition mechanisms and heats of combustion determined for each of the fuel species tested in this work. Model-predicted fire spread rate in these simulations varied between 0.34 m s−1 and 0.80 m s−1 demonstrating a notable dependence (up to a factor of 2x) on measured variations in thermal decomposition mechanism and a second-order dependence on the use of either reaction-step-specific or single (global) heats of combustion.

Experimental and simulation study of peanut shell-derived activated carbon and syngas production via integrated pyrolysis-gasification technique

Carbonaceous materials are among the most appropriate and widely used materials in the field of energy production, conversion, and storage. According to recent studies, biochar-based catalytic supports and adsorbents have shown great potential in the fields of energy production and the adsorption and storage of various gases due to their adjustable surface chemistry and porosity. In the present study, the pyrolysis of peanut shell to produce activated carbon as a precursor for catalyst support was investigated. Acid washing pretreatment was performed on raw biomass before pyrolysis to remove metals and impurities and reduce the ash content of the biomass. Before pyrolysis, thermogravimetric analysis was performed to determine the temperature range of biomass thermal decomposition. Pyrolysis was carried out at temperatures of 300, 400, and 500 °C to study the effect of pyrolysis temperature on biochar yield. KOH-activation on biochar was followed by subsequent pyrolysis at 650 °C to produce activated carbon. To study the effect of pyrolysis temperature and KOH activation on the structural and physiochemical characteristics of biochar, nitrogen adsorption/desorption and FTIR analyses were conducted. The pore size of the activated carbon surface changed from mesoporous to microporous with increasing the pyrolysis temperature and subsequent KOH activation, and the biochar specific surface area increased from 3.5 to 363.1 m2 g-1. In order to evaluate and optimize the operating conditions of the biochar and syngas production processes on larger scales, the integrated pyrolysis and gasification processes were simulated in Aspen Plus software. The effects of temperature, pressure, and air to biomass ratio on biochar production rate and H2/CO ratio were evaluated. A temperature of 650 °C, a pressure of 1 bar and an air to biomass ratio of 0.1 were selected as optimum operating conditions to simultaneously achieve maximum biochar production and maintain the quality of synthetic gas. The findings of the experimental and simulation sections of this study could provide a useful guide for the industrial-scale production of biochar and activated carbon as a catalytic support in various chemical production processes, as well as a water polutant adsorbent and gas adsorbent for various gas purification and storage processes.

Pyrolysis of sludge briquettes for the preparation of cylindrical-shaped biochar and comparison between CO2 and steam activation

Sludge briquettes were prepared through briquetting (under the pressure of 25 MPa) of half-dried sewage sludge with moisture content of 30 wt%, and the cylindrical-shaped biochar (CSB) was obtained by subsequent pyrolysis (600 °C) and CO2/steam activation (650–950 °C). Briquetting process showed great influence on the pyrolysis of sewage sludge. The temperature range for the organic decomposition increased from 150 to 500 °C for the sludge without briquetting to 150–700 °C for the sludge briquette. The mechanical performance of CSBs was greatly influenced by activation temperature. The axial compressive strength of the CO2/steam activated CSBs were in the range of 17.8–22.2 kg·cm‑2 at the activation temperature of 650 °C and 800 °C, but dropped markedly when the activation temperature increased to 950 °C. CSBs were negatively charged and rich in oxygen/nitrogen-containing functional groups like –OH, –COOH, amines and amides, and the specific surface area of the optimal steam and CO2-activated CSB were 123.2 and 113.5 m2·g‑1, respectively. The prepared CSBs were applied in methylene blue (MB) adsorption, and the maximum adsorption capacity of 513.81 and 419.29 mg·g‑1 could be achieved by the CO2 and steam-activated CSB, respectively. Both physical and chemical adsorptions played important role in the MB adsorption. Finally, the regeneration test showed that optimal samples of the CO2 and steam-activated CSB still retained around 90 % of its original adsorption capacity after three cycles of adsorption-regeneration tests, but the mechanical performance dropped by 58.1 % and 47.8 %, respectively.

Prediction model for crack sensitive temperature region and phase fractions of slab under continuous casting cooling rates based on finite number of experiments

Accurate prediction of the crack sensitive temperature region and phase fractions variation of slabs during continuous cooling is an important guide to avoid cracks and effectively control the quality. Based on finite number of measurements, at different cooling rates of the continuous casting process, a prediction model for characteristic temperatures of austenite decomposition, the variation of phase fractions with temperature, the crack sensitive temperature regions, and the final microstructural compositions of casting slabs at different cooling rates has been established and evaluated the accuracy. The results show that austenite decomposition temperature range moves toward the low temperature region as cooling rate increases, and the independent peak of ferrite transition become weaker. The characteristic temperatures of austenite decomposition can be quantitatively calculated by TC(CR) = A−exp(B + C/CR) at different cooling rates, which the maximum relative error for experimental steels is −2.2%. The ferrite and pearlite phase fractions increases with decreasing temperature during continuous casting cooling, which means that the ability of the billet to resist deformation and external force changes. Meanwhile, the final ferrite content of slabs for Steel B and Steel C at different cooling rates are 83.24620−exp(2.59364–13.72283/CR) and 85.07143−exp(1.71320–15.82244/CR), respectively. The crack sensitive temperature region Ae3 ∼ Tα40%(CR) calculated by the prediction model is in good agreement with the low ductility zone measured by experiment. Moreover, the critical temperatures Tα40%(CR) of the crack sensitive temperature regions are 890.35731−exp(2.99719–20.67781/CR), 745.87462−exp(4.83056–44.18511/CR) and 729.46168−exp(2.96621–12.21949/CR) for three experimental steels under different cooling rates.

Synthesis of CuII and CdII Metal-Organic Frameworks Based on 4,5-Bis(1-hydroxytetrazol-5-yl)-1,2,3-triazole and Their Effects as the Catalyst in Ammonium Perchlorate Thermal Decomposition.

Two new three-dimensional (3D) energetic metal-organic frameworks (EMOFs), namely, [Cu(OBTT)(NC2H8)2]n (1) and [Cd3(OBTT)2(H2O)2]n·4H2O (2), where H3OBTT = 4,5-bis(1-hydroxytetrazol-5-yl)-1,2,3-triazole, were prepared, and their structures were characterized by single-crystal X-ray diffraction analysis, which revealed that the EMOFs feature a rigid 3D framework architecture. The possibility of these two EMOFs as potential catalysts for the thermal decomposition of ammonium perchlorate (AP) was investigated. The results show that they have significant catalytic activity, up to reducing the peak temperature of AP decomposition from 704.0 to 613.6 K and contracting the decomposition temperature range from 451 to 320 K, which is almost one-third less than the decomposition temperature range of pure AP. The Kissinger and Ozawa-Doyle methods were used to calculate the kinetic parameters of the thermal decomposition of pure and mixed AP samples. The experimental results suggest that compound 1 has potential applications in the field of explosives and propellants. All properties suggest that compound 1 can be used as a potential catalyst.

Thermal Degradation Behavior and Mechanism of Organosilicon Modified Epoxy Resin

AbstractOrganosilicon modified epoxy resin is one of the most widely used ablative coating matrices in the whole aerospace industry. However, most research focuses on the final effect of organosilicon modification, while systematic studies on thermal degradation behavior and mechanism of organosilicon modified epoxy resin are rarely reported. In this work, a heat‐resistant epoxy resin (ES231) is prepared through the condensation reaction between epoxy resin and methylphenyl organosilicon intermediate. The TGA test results show that the integral procedural decomposition temperature (IPDT), the thermal residual weight at 800 °C (R800), and decomposition temperature range all improve under both N2 and air atmospheres after modification. The functional groups variation of polymers and the generated volatile segments during the degradation process are measured by FTIR, TG‐IR, and TG‐MS to investigate the thermal degradation mechanism in detail. Meanwhile, the composition and microstructure of the solid residue after thermal degradation are also systematically studied by SEM, XPS, and Raman spectroscopy. It is expected that this work can provide some theoretical basis and new ideas for designing new heat‐resistant epoxy resin.

Synthesis and characterization of a heterogeneous catalyst from a mixture of waste animal teeth and bone for castor seed oil biodiesel production

The present study focused on the synthesis of heterogeneous catalyst from a mixture of waste animal teeth and bone through thermal method. The produced catalyst was used for castor seed oil (CO) biodiesel production. A different mixing ratio of teeth and bone was used with a calcination temperature range from 650 °C to 1250 °C with 100 °C increment for 3h calcination duration. Thermogravimetric analysis (TGA) for animal teeth and bone was performed to identify the common decomposition temperature range. The effect of calcination temperature on basicity of the catalyst and yield of biodiesel was studied for each teeth and bone mixing ratio. Maximum basicity of 6.12mmol HCl/g and biodiesel of 89.5wt% was obtained by mixing ratio of 25wt% teeth and 75wt% bone at calcination temperature of 1150 °C for 3h. The purity of the produced biodiesel in terms of mono fatty acid methyl esters (FAME) formation was found to be 92.6%. X-ray Diffraction (XRD), X-Ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FT-IR) and TGA was used to characterize the raw and produced catalyst. The maximum yield of FAME (89.5wt% with 92.6% purity) was obtained by 5wt% catalyst loading and 9:1 M ratio of methanol to castor seed oil at 60 °C reaction temperature for 3h. Compositional analysis of the produced CO FAME was performed by FT-IR, gas chromatography-mass spectroscopy (GC-MS) and nuclear magnetic resonance (NMR). The performance of the produced catalyst was also checked using its reusability for transesterification CO. Further, the physico-chemical properties including rheological properties of the produced CO FAME were characterized by ASTM methods to check its suitability as a liquid biofuel.

Measurement of organic and elemental carbon in the char deposits from the combustion of permitted and undesirable fuels in domestic boilers

Burning solid fuels in domestic boilers during the heating season increases the concentrations of dust containing carbonaceous particles that exist as organic carbon (OC) and elemental carbon (EC). For economic reasons, plastic wastes are also incinerated with traditional energy fuels. In this study, fossil fuels (bituminous coal and lignite) and biomass (softwood and hardwood) together with an addition of different types of plastics (HDPE, LDPE, PP, and PET) were combusted in domestic boilers. Carbonaceous matter in deposits (char and soot) from the combustion of fuels and fuels with added plastics has been examined by the thermo-optical method using an OCEC Lab analyser. The addition of plastics significantly changes the concentrations of individual carbon forms. The temperature range of the EC2 fraction (740 – 840 °C) includes the charring of plastics and OC3 (480 – 580 °C) and corresponds to the temperature range for polymer decomposition. Deposits from bituminous coal combustion contained EC2 = 10.28 mg/kg of combusted fuels, and OC3 = 1.25 mg/kg of combusted fuels. After the addition of plastics to bituminous coal, the concentrations of EC2 = 23.91 mg/kg, OC3 = 3.13 mg/kg of combusted household fuels increased. Similar changes in the concentrations of the EC2 and EC3 fractions were found after adding plastics to biomass and lignite. The method can be used for the preliminary identification of “banned fuels” in domestic boilers.

Further study on energetic salts of TNATT anion

Six energetic salts based on fully nitroamino-functionalized fused-triazole were synthesized. All salts were characterized by IR, multinuclear NMR spectroscopy, thermal analysis and elemental analysis. The crystal structures of salts 2, 3, and 6 were confirmed by single-crystal X-ray diffraction. The densities of all salts lie in the range between 1.77 and 1.83 g cm−3, whilst their decomposition temperatures range within 142–200 °C. Most energetic salts are slightly more sensitive than RDX. The calculated detonation pressures and velocities (Gaussian 09 and EXPLO5) of salts 2–7 range within 21.7–39.3 Gpa and 7867–9401 m s−1, respectively. Salt 7 exhibits a high density (1.83 g cm−3), acceptable thermal stability (Td = 179 °C) and sensitivity (IS = 7 J, FS = 216 N), and excellent detonation performance (vD = 9401 m s−1, P = 39.3 GPa), which suggest that salt 7 may well have promising applications as high-energy–density materials.

Mercury release behaviors of Guizhou bituminous coal during co-pyrolysis: Influence of chlorella

Co-pyrolysis of coal and seaweed can not only effectively decrease the carbon footprint but also improve the quality and output of coal pyrolysis products, however, the influence of seaweed on thermal releasing behaviors of mercury during co-pyrolysis process are still unclear. In this work, the chlorella and Guizhou bituminous coal were mixed and used to reveal the mercury release behavior during co-pyrolysis by the temperature programmed pyrolysis experiments, thermogravimetric and differential thermogravimetric analysis (TG-DTG) and thermogravimetry-mass spectrometry (TG-MS) methods, offering a sufficient explanation on the control technology of mercury pollutants in co-pyrolysis. The results exhibited that a large amount of reducing gases such as CO, H2 and H2O were generated in chlorella at the temperature range of 100-500°C, which was favorable for the transformation from oxidized mercury to elemental mercury, thus remarkably increased the release of elemental mercury in the raw coal sample. The mixed chlorella also significantly lowered the decomposition temperature range (from 400-600 to 300-400°C) of pyrite-bound mercury and decreased the decomposition temperatures of the pyrite-bound mercury species. Additionally, in the co-pyrolysis about 91.82% of mercury was released into the gas phase below 400°C and was 13.77% higher than that of in individual pyrolysis of coal.

Flame Retardant Properties and Mechanical Properties of Polypropylene with Halogen and Halogen-Free Flame Retardant System

In this study, to improve the flame retardancy properties of polypropylene, DBDPE/Sb2O3 and DBDPE/HBCD/Sb2O3 flame retardant systems were used for flame retardant PP, and a halogen-free flame retardant PP material was prepared using the one-component intumescent flame retardant PNP1D. Tensile tests, impact tests, ultimate oxygen index, UL94V-0 vertical combustion, thermogravimetric analysis, rheological analysis and scanning electron microscopy were used to study the flame retardant properties and mechanical properties of the flame retardant PP. The test results show that both the ultimate oxygen index of DBDPE/Sb2O3 compounded flame retardant PP and the ultimate oxygen index of PNP1D flame retardant PP are nearly double that of pure PP, passing the UL-94V-0 flame retardant standard. The thermal decomposition temperature range of DBDPE/Sb2O3 compounded system and the thermal decomposition temperature range of PNP1D flame retardant PP both completely cover the thermal decomposition temperature range of both the DBDPE/Sb2O3 compound system and PNP1D flame retardant PP completely covered the thermal decomposition temperature range of pure PP. The tensile and impact strength of the DBDPE/Sb2O3 flame retardant system with 10% SK-80 is 50% higher than that of the DBDPE/Sb2O3 flame retardant system without SK-80. The modified PP with 25% PNP1D is nearly 1 time higher than pure PP in terms of carbon formation and has an ideal flame retardant effect.