scholarly journals Thermal Oxidative and Non-Oxidative Degradation Behaviour of Afuze Coal

2021 ◽  
Author(s):  
Bemgba B. Nyakuma
Keyword(s):  
Combustion Process ◽  
Oxidative Degradation ◽  
Chemical Properties ◽  
Degradation Process ◽  
Oxidative Process ◽  
Compact Structure ◽  
Degradation Behaviour ◽  
Oxidative Pyrolysis ◽  
Thermal Degradation Process ◽  
Edo State

This study presents a preliminary analysis of the chemical and thermal fuel properties of Afuze (AFZ) coal extracted from coalfields in Owan East Local Government Area of Edo State, Nigeria. The chemical properties of AFZ were examined by combined scanning electron microscopy-energy dispersive X-ray (EDX), whereas the thermal properties were deduced by thermogravimetric analysis (TGA) under flash (50 °C/min heating rate) oxidative (combustion) and non-oxidative (pyrolysis) conditions. The microstructure and morphology analysis of AFZ revealed has a compact structure comprising small-to-large, irregular shaped and exfoliated grains with a vitreous appearance typically ascribed to metal elements (Ti and Fe) kaolinite, quartz, and other clay minerals. Chemical analysis revealed carbon, oxygen, aluminium, silicon, sulphur, calcium, titanium, and iron in major and minor (trace) quantities. Thermal analysis under oxidative and non-oxidative conditions revealed degradation occurs in three stages, namely; drying or demineralisation, devolatilization or maceral degradation and the formation of char/coke or ash. Lastly, the findings showed that the temperature range for the oxidative thermal degradation process (338.58 - 756.76 °C) was higher than the non-oxidative process (378.43 - 615.34 °C). This observation can be explained by the exothermic nature of the oxidative (combustion) process, which ensures greater heat supply required to thermally soften or degrade the maceral coal components. Overall, the oxidative process yielded the residual mass (RM = 21.97%) and mass loss (ML = 78.03%). The lower ML (49.03%) but higher RM (50.97%) observed during non-oxidative degradation of AFZ could be ascribed to the largely endothermic nature of the process.

Oxidative Degradation Monitoring of Natural Rubber Using S K-Edge X-Ray Absorption near-Edge Spectroscopy (XANES)

2012 ◽  
Vol 620 ◽  
pp. 440-445 ◽  
Author(s):  
Wirach Taweepreda ◽  
Wanwisa Limphirat ◽  
Prayoon Songsiriritthigul
Keyword(s):  
Natural Rubber ◽  
Oxidative Degradation ◽  
Chemical Properties ◽  
Oxidative Process ◽  
Tetramethylthiuram Disulfide ◽  
Edge Structure ◽  
X Ray ◽  
Degradation Monitoring ◽  
Zinc Diethyldithiocarbamate ◽  
X Ray Absorption

In this work, we present the results of sulfur crosslinking and degradation in natural rubber (NR) studied by X-ray absorption near-edge structure spectroscopy (XANES). Sulfur K-edge XANES spectra has been collected and analyzed to provide the geometry and electronic environment of sulfur crosslinks during vulcanization and degradation processes by ozone aging. We found that reversion took place before the onset of oxidative process at the sulfur bridge. Parallel to the oxidative process, the production of cyclic sulfanes took places. This physico-chemical properties which were calculated from S K-edge XANES spectra were correlated with the mechanical of NR films by varying accelerator type. The accelerator zinc diethyldithiocarbamate (ZDEC) gave highest film strength when compared with other accelerators: N-cyclohexylbenzothiazole sulfenamide (CBS), 2,2' dibenzothiazyl disulfide (MBTS), and tetramethylthiuram disulfide (TMTD).

Kinetic study of the stabilizing effect of aluminum trihydroxide on thermal degradation of epoxy resin

e-Polymers ◽  
2014 ◽  
Vol 14 (2) ◽  
pp. 133-137 ◽  
Author(s):  
Jiangbo Wang ◽  
Jialin Fang ◽  
Chengwei Wang ◽  
Yongyou Li ◽  
Mengjiao Huang
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Epoxy Resin ◽  
Fire Retardant ◽  
Degradation Process ◽  
Ozawa Method ◽  
Degradation Behaviour ◽  
Stabilizing Effect ◽  
Thermal Degradation Process ◽  
Aluminum Trihydroxide

AbstractThe stabilizing effect of epoxy resin (EP)/aluminum trihydroxide (ATH) was measured by thermogravimetric analysis (TGA) in an N2 flow. The Kissinger and Flynn-Wall-Ozawa methods were used to determine the activation energy of non-isothermal degradation at different stages. The results showed that there was a slight increase in activation energy after ATH was added. It confirms the fire-retardant effect of ATH on the thermal degradation behaviour of pure EP. The Flynn-Wall-Ozawa method showed that flame-retardant ATH remarkably enhanced the activation energy of the thermal degradation process for EP, albeit the conversion rate being only 10%, which demonstrated the stabilization of ATH to the char layer of EP.

Extraction and Determination of Physico-chemical Properties of Oil from Watermelon Seeds (Citrullus lanatus L) to Use in Internal Combustion Engines

2017 ◽  
Vol 68 (11) ◽  
pp. 2676-2681
Author(s):  
Mihaela Gabriela Dumitru ◽  
Dragos Tutunea
Keyword(s):  
Fatty Acid ◽  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Citrullus Lanatus ◽  
Combustion Process ◽  
Chemical Properties ◽  
Physico Chemical ◽  
Mean Diameter ◽  
Geometrical Mean ◽  
Reduction Of Nox

The purpose of this work was to investigate the physicochemical properties of watermelon seeds and oil and to find out if this oil is suitable and compatible with diesel engines. The results showed that the watermelon seeds had the maximum length (9.08 mm), width (5.71mm), thickness (2.0 mm), arithmetic mean diameter (5.59 mm), geometrical mean diameter (4.69 mm), sphericity (51.6%), surface area (69.07), volume 0.17 cm3 and moisture content 5.4%. The oil was liquid at room temperature, with a density and refractive index of 0.945 and 1.4731 respectively acidity value (1.9 mgNaOH/g), free fatty acid (0.95 mgNaOH), iodine value (120 mgI2/100g), saponification value (180 mgKOH/g), antiradical activity (46%), peroxide value (7.5 mEqO2/Kg), induction period (6.2 h), fatty acid: palmitic acid (13.1%), stearic acid (9.5 %), oleic acid (15.2 %) and linoleic acid (61.3%). Straight non food vegetable oils can offer a solution to fossil fuels by a cleaner burning with minimal adaptation of the engine. A single cylinder air cooled diesel engine Ruggerini RY 50 was used to measure emissions of various blends of watermelon oil (WO) and diesel fuel (WO10D90, WO20D80, WO30D70 and WO75D25). The physic-chemical properties of the oil influence the combustion process and emissions leading to the reduction of NOX and the increase in CO, CO2 and HC.

Structural comparisons of pyrodextrins during thermal degradation process: The role of hydrochloric acid

2021 ◽  
Vol 349 ◽  
pp. 129174
Author(s):  
Huijia Mao ◽  
Zhijun Chen ◽  
Jie Li ◽  
Xueyang Zhai ◽  
Hongyan Li ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Thermal Degradation ◽  
Degradation Process ◽  
Thermal Degradation Process

scholarly journals Heat Aged Tensile Strength Retention of Poly (p-phenylene terephthalamide) Sewing Thread

2008 ◽  
Vol 3 (4) ◽  
pp. 155892500800300 ◽  
Author(s):  
Walter R. Hall ◽  
Warren F. Knoff
Keyword(s):  
Hydrolytic Degradation ◽  
Oxidative Degradation ◽  
Thermal Exposure ◽  
Strength Loss ◽  
Degradation Process ◽  
Downstream Processing ◽  
Kink Bands ◽  
Sewing Thread ◽  
Continuous Filament ◽  
Strength Retention

The strength retention after exposure to elevated temperature in air of continuous filament and staple spun PPTA sewing thread and the precursor yarns was determined. For both types, the process of converting the greige yarn to thread reduced the amount of strength retained after thermal exposure. The continuous filament products retained more strength than the staple products. The data was fitted to a kinetic rate model in which two strength loss processes occurred. The first process occurred within about the first 5 minutes of thermal exposure and is hypothesized to be hydrolytic degradation. The estimated secondary degradation process activation energy suggests this to be thermo-oxidative degradation. Optical microscopy of filaments indicates a higher level of kink banding and other damage in continuous filament versus staple products and in finished thread versus the precursor yarns. The kink bands and damage are believed to be caused by the staple manufacturing process and the downstream processing of precursor yarn to finished sewing thread. The kink bands and damage are hypothesized to be responsible for the differences in strength retention.

Physico-chemical Properties, Biological and Environmental Impact of Nb-saponites Catalysts for the Oxidative Degradation of Chemical Warfare Agents

2017 ◽  
Vol 2 (5) ◽  
pp. 1812-1819 ◽  
Author(s):  
Daniele Costenaro ◽  
Chiara Bisio ◽  
Fabio Carniato ◽  
Sergey L. Safronyuk ◽  
Tatyana V. Kramar ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Oxidative Degradation ◽  
Chemical Properties ◽  
Chemical Warfare Agents ◽  
Chemical Warfare ◽  
Physico Chemical ◽  
Warfare Agents

scholarly journals Modelling of pollutants concentrations from the biomass combustion process

2011 ◽  
Vol 32 (4) ◽  
pp. 423-433 ◽  
Author(s):  
Aneta Magdziarz ◽  
Małgorzata Wilk ◽  
Monika Zajemska
Keyword(s):  
Computer Simulation ◽  
Coming Out ◽  
Combustion Process ◽  
Chemical Properties ◽  
Biomass Combustion ◽  
Physical And Chemical Properties ◽  
Influence Of Temperature ◽  
Complex Phenomena ◽  
Physical And Chemical ◽  
And Chemical Properties

Modelling of pollutants concentrations from the biomass combustion process This paper presents possibilities for of numerical modelling of biomass combustion in a commercially available boiler. A sample of biomass was tested with respect to its physical and chemical properties. Thermogravimetry studies of biomass were carried out. Computer simulation makes it possible to analyse complex phenomena which are otherwise difficult to observe. The aim of this work was to model biomass combustion to predict the amount of pollutants generated (NOx, CO, SO2) in the exhaust gases coming out from boilers The calculations were made using the CHEMKIN program. Results of calculations were performed taking into account the influence of temperature, pressure and residence time.

Non-isothermal degradation kinetics for polycarbonate/ polymethylphenylsilsesquioxane composites

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiangbo Wang ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Flame Retardancy ◽  
Degradation Kinetics ◽  
Degradation Process ◽  
Nitrogen Atmosphere ◽  
Ozawa Method ◽  
Degradation Behaviors ◽  
Thermal Degradation Process

AbstractThe thermal degradation behaviors of PC/PMPSQ (polymethylphenylsilsesquioxane) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. During non-isothermal degradation, Kissinger and Flynn-Wall-Ozawa methods were used to analyze the thermal degradation process. The results showed that a remarkable decrease in activation energy ( E ) was observed in the early and middle stages of thermal degradation in the presence of PMPSQ, which indicated that the addition of PMPSQ promoted the thermal degradation of PC. Flynn-Wall-Ozawa method further revealed that PMPSQ significantly increased the activation energy of PC thermal degradation in the final stage, which illustrated that the PMPSQ stabilized the char residues and improved the flame retardancy of PC in the final period of thermal degradation process

scholarly journals A thermal degradation study of Y and La methanesulfonates

2006 ◽  
Vol 71 (8-9) ◽  
pp. 905-915
Author(s):  
Moura de ◽  
Jivaldo Matos ◽  
Farias de
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Differential Thermal Analysis ◽  
Thermal Degradation ◽  
Degradation Process ◽  
Oxide Formation ◽  
Scanning Calorimetry ◽  
Degradation Study ◽  
Thermogravimetric Data ◽  
Thermal Degradation Process

The synthesis, characterization and thermal degradation of yttrium and lanthanum methanesulfonates is reported. The prepared salts were characterized by elemental analysis and infrared spectroscopy. The thermal degradation study was performed using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC).Using the thermogravimetric data, a kinetic study of the dehydration ofY and Lamethanesulfonates was performed employing the Coats-Redfern and Zsak?methods. It was verified that under heating, yttrium and lanthanum methanesulfonates undergo three main processes: dehydration, thermal degradation and oxide formation. Furthermore, depending on the nature of the atmosphere, i.e., inert or oxidant, the thermal degradation process could be endothermic (N2) or exothermic (air).

scholarly journals Effect of char layer on transient thermal oxidative degradation of polyethylene

2007 ◽  
Vol 11 (2) ◽  
pp. 23-36 ◽  
Author(s):  
Javad Esfahani ◽  
Ali Abdolabadi
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Solid Phase ◽  
Early Stage ◽  
Radiation Heat Transfer ◽  
Oxidative Degradation ◽  
Degradation Process ◽  
Thermal Oxidative Degradation ◽  
Char Layer ◽  
Effect Of Oxygen

A transient one dimensional model has been presented to simulate degradation and gasification of polyethylene, in early stage of fire growth. In the present model effect of oxygen on degradation and rate of polymer gasification while the sample is subjected to an external radiative heat source is numerically investigated. This model includes different mechanism, which affect the degradation process, such as in depth thermal oxidative decomposition, in depth absorption of radiation, heat transfer, volatiles advection in solid phase and convective heat transfer on surface. Also effects of radiative parameters, due to formation of char layer such as surface reflectivity and absorptivity on thermal degradation of polyethylene are investigated. The results for 40 kW/m2 heat source are reported and yielded realistic results, comparing to the published experimental data. The results show that an increase in oxygen concentration leads to considerable increase in gasification rate and also leads to sharp increase of surface temperature. .

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