Thermal Degradation Characteristics Research Articles

Thermal degradation and compositional changes of wood treated in a semi-industrial scale reactor in vacuum

Heat treatment is an eco-friendly and efficient way to improve the defective properties of woods, such as hygroscopic nature, lack of dimensional stability, and low resistance against biological degradation, and to produce a green and sustainable wood material for construction and buildings. The aim of this study is to investigate the thermal degradation of a hardwood (poplar, Populus nigra) and a softwood (fir, Abies pectinata) in a semi-industrial scale reactor in which a vacuum environment is adopted to intensify the thermal degradation process. Four different stages of thermal degradation during wood heat treatment are defined, based on the intensity of differential mass loss (DML). Meanwhile, a number of analyses on untreated and treated woods are performed to evaluate their thermal degradation characteristics and compositional change during treatment. The FTIR analysis clearly demonstrates the thermal degradation through dehydration, deacetylation, depolymerization, and condensation reactions during the heat treatment. In addition, the XRD analysis indicates an increase in relative crystallinity of cellulose. The correlation of devolatilization index (DI) with respect to mass loss of the two wood species is strongly characterized by linear distribution, which is able to provide a simple and useful tool in predicting mass loss of wood treated in wood industry.

Thermal and Calorimetric Evaluations of Polyacrylonitrile Containing Covalently-Bound Phosphonate Groups.

One of the effective ways to enhance flame retardance of polyacrylonitrile (PAN) is through a reactive route, primarily developed in our laboratories, which involved chemical modification reactions utilising phosphorus-containing comonomers. In the present study, diethyl(acryloyloxymethyl)phosphonate (DEAMP) and diethyl(1-acryloyloxyethyl)phosphonate (DE1AEP) were synthesised and copolymerised with acrylonitrile (AN), under radical initiation in an inert atmosphere, in aqueous slurries. The thermal degradation and combustion characteristics as well as the extent of flame retardation were mainly assessed with the aid of various thermo-analytical and calorimetric techniques. It was found that the incorporation of phosphonate groups in polymeric chains of PAN resulted in improved flame-retardant characteristics. Furthermore, it was observed that the actual chemical environment of the phosphorus atom in the acrylic phosphonate modifying groups has little effect on the overall thermal degradation and combustion behaviours of the modified PAN systems. It was also observed that the predominant mode of flame retardance occurred in the condensed phase.

Thermal degradation of carbohydrates, proteins and lipids in microalgae analyzed by evolutionary computation

The kinetics of microalgae pyrolysis is investigated to analyze the thermal degradation of carbohydrates, proteins and lipids in different species of microalgae. The pyrolysis processes of microalgae Chlorella vulgaris ESP-31, Nannochloropsis oceanica CY2, and Chlamydomonas sp. JSC4 are examined by thermogravimetric analysis (TGA), and independent parallel reaction (IPR) model is adopted to approach the pyrolysis kinetics. To maximize the fit quality between the established kinetic models and experimental data, particle swarm optimization (PSO), a kind of evolutionary computation, is employed. The thermal degradation characteristics of the three microalgal species are compared with each other. The results suggest that the thermal degradation curves of the three microalgae can be predicted with a fit quality of at least 97.9%. The activation energies of carbohydrates, proteins, and lipids in the microalgae are in the ranges of 53.28–53.30, 142.61–188.35, and 40.21–59.23 kJ mol−1, respectively, while the thermal degradation of carbohydrates, proteins, and lipids are in temperature ranges of 164–497, 209–309, and 200–635 °C, respectively. It is proved in this work that the IPR model and the calculation of the PSO can be used to predict the pyrolysis kinetics of microalgae to a good level of fitness.

Controlled High Filler Loading of Functionalized Al2O3-Filled Epoxy Composites for LED Thermal Management

Thermal management in light-emitting diode (LED) has been extensively researched recently. This study is intended to develop an effective thermally conductive epoxy composite as thermal interface material (TIM) for headlamp LEDs. Silane-functionalized aluminum oxide (Al2O3) powder of different average particle sizes (44 and 10 µm) was studied for its feasibility as filler at its maximum loading. A detailed comparison of three different methods of particle dispersions, hand-mix, speed-mix and calendaring process (3-roll mill), has been reported. The dispersion of Al2O3 particles, the thermal conductivity and thermal degradation characteristics of the composites were investigated and explained in detail. At 75 wt.% filler loading, 10 and 44 µm Al2O3 achieved composite thermal conductivities of 1.13 and 2.08 W/mK, respectively, which is approximately 528 and 1055% of enhancement with respect to neat epoxy. The package-level thermal performance of the LED employing the Al2O3-filled TIMs was carried out using thermal transient analysis. The experimental junction-to-ambient thermal resistances (RthJ-A) achieved were 6.65, 7.24, and 8.63 K/W for Al2O3_44µm, Al2O3_10µm and neat epoxy, respectively. The results revealed that the Al2O3_44µm fillers-filled composite performed better in both material-level and package-level thermal characteristics.

Mechanical, flammability and thermal degradation characteristics of rice straw fiber-recycled polystyrene foam hard wood composites incorporating fire retardants

Hard wood–polymer composite (HWC) was prepared, based on hot press technique, by mixing air-dried rice straw waste as a filler into a molten of chemically recycled extended polystyrene foam waste (PS) and its maleated form (PS-g-MA) as a matrix. Two fire retardants (FRs), namely zinc borate (ZB) and/or anhydrous magnesium hydroxide (MH), were dispersed into the composite to compensate for the poor thermal stability and flammability of the composite. Thermal properties of the reached HWC were evaluated by different techniques including thermogravimetric analysis, differential scanning calorimetric, in addition to, flammability analyses. Mechanical characterization was, also, rated based on tensile strength and elongation at break measurements. It was found that incorporation of the nominated fire retardants improved the thermal stability of the final products. Besides, flammability resistance was enhanced as ZB and/or MH was added to the hard wood–polymer composite formulation. The onset temperature of degradation and mass loss rates were significantly reduced in the presence of the FRs. The tensile strength of HWC was reinforced by marked additions of the FRs. The obtained data can fulfill the required optimal performance of the HWC to fire and mechanical characterizations which are necessary for many applications in the residential construction, transportation and furniture industries.

Synthesis of novel phosphorus-based flame retardants containing 9,9-bis (4-hydroxyphenyl) fluorine and their reinforcements on the fire safety of polypropylene

Fabricating an effective synergism to improve the flame-retardant (FR) efficiency is recently considered to be a very promising way to prepare high-efficient FRs system. A novel FRs containing phosphorus and (4-hydroxyphenyl) fluorene have been synthesized and characterized by FTIR, 1H NMR and MS. The FRs were then incorporated into polypropylene (PP) in different ratios, and then, ammonium polyphosphate (APP) was added to the FRs/PP system, with subsequent investigation into the synergistic effects between FRs and APP. Limited oxygen index (LOI), UL-94 test and cone calorimeter test were adopted to investigate the FR properties of the flame-retardant PP composites. The LOI value is as high as 31.0%, when FRs/APP is 2/3. Moreover, due to the synergistic FR effects between FRs and APP, the pHRR of PP7 decreases from 783 kW m−2 (PP0) to 110 kW m−2 (PP7), which is 85% lower than those of PP. Meanwhile, thermogravimetric analysis (TG) was used to study the thermal degradation characteristics of the PP composites. The char residues increased from 0.02 mass% to 15.85 mass% at 650 °C when FRs/APP is 3:2, indicating that there are synergistic flame-retarding effects between FRs and APP. Generally, the stable char layers of FR/APP/PP composites are responsible for the improved FRs properties, and the char layers could not only effectively prevent the release of combustion gases from releasing but also hinder the propagation of oxygen and heat into the interior substrate.

Kinetics of thermal degradation of a Japanese oil sand

Thermal degradation characteristics of a Japanese oil sand at different heating rates (10, 20, and 30°C/min), and 30ml/min air flow rate have been investigated. The kinetic parameters have been calculated based on three stages of weight loss and/or the conversion of the sample. These include, stage 1 (SI): volatilization of moisture content and the light hydrocarbon (20–227°C), stage 2 (SII): combustion of heavy hydrocarbon (227–527°C), and stage 3 (SIII): oxidative decomposition of carbonaceous organic matter (502–877°C). The results showed that the rate of change of the oil sand conversion with time dαdt was affected by the heating rate. The time taken by the system to reach 0.99 conversion was observed as 85, 50, and 35min at the heating rates of 10, 20, and 30°C/min, respectively. The frequency factor, A, at SI was between 0.09 and 0.54min−1, while the activation energy, Ea, was 11.2–12.5KJmol−1 (the percentage weight loss, Wt, was 0–3.6%w/w; and the conversion, α, was 0–0.2.). At SII, the values of A and Ea were 2.1–5.5min−1 and 17.6–19KJmol−1, respectively (Wt=3.1–15.88%w/w; α=0.17–0.86.). The value of A at SIII was 5.5E11–1.1E13min−1, while Ea was 160–200KJmol−1 (Wt=15.33–17.99%w/w; and α=0.84–0.99).

Thermal degradation characteristics and products obtained after pyrolysis of specific polymers found in Waste Electrical and Electronic Equipment

Modern societies strongly support the recycling practices over simple waste accumulation due to environmental harm caused. In the framework of sustainable recycling of plastics from WEEE, pyrolysis is proposed here as a means of obtaining secondary value-added products. The aim of this study was to investigate the thermal degradation and the products obtained after pyrolysis of specific polymers found in the plastic part of WEEE, using thermogravimetric analysis and a pyrolizer equipped with a GC/MS. Polymers studied include ABS, HIPS, PC and a blend having a composition similar to that appearing in WEEE. It was found that, PC shows greater heat endurance compared to the other polymers, whereas ABS depolymerizes in three-steps. The existence of several polymers in the blend results in synergistic effects which decrease the onset and final temperature of degradation. Moreover, the fragmentation occurred in the pyrolyzer, at certain temperatures, resulted in a great variety of compounds, depending on the polymer type, such as monomers, aromatic products, phenolic compounds and hydrocarbons. The main conclusion from this investigation is that pyrolysis could be an effective method for the sustainable recycling of the plastic part of WEEE resulting in a mixture of chemicals with varying composition but being excellent to be used as fuel retrieved from secondary recycling sources.

A study of the effect of thickness on the thermal degradation and flammability characteristics of some composite materials using a cone calorimeter

In this article, we report on our investigation regarding the influence of the thickness on the thermal and fire response characteristics of two types of composite materials. For this purpose, carbon fibre–reinforced epoxy and glass fibre–reinforced phenolic resin samples, differing in thicknesses, were chosen. The primary aim was to investigate the effect of using multiple layers on the thermal degradation and fire reaction properties of the composite material using a cone calorimeter. The results showed that the primary fire reaction parameters such as the time to ignition and peak heat release rates depended on the number of the layers. Furthermore, the amount of smoke released during the thermal degradation was found to decrease as the number of layers increased. In addition, the carbon dioxide emission levels were also observed to be dependent on the number of layers.

Effect of Na+ and Ca2+ on the Thermal Degradation of Carboxymethylcellulose in Air

Carboxymethylcellulose (CMC), including the acid form (CMC-H) and salt forms (CMC-Na, CMC-Ca), were prepared for the survey of thermal degradation and the CMC-H was obtained by acidifying CMC-Na with HCl. An online-coupled thermogravimetric (TG)-FTIR evolved gas analysis instrument was used to identify and monitor the evolution of gaseous products during the thermal degradation of CMC in air. The thermal degradation characteristics of CMC-H and salt forms CMC-Na, CMC-Ca of carboxymethylcellulose were compared to determine the effect of Na+ and Ca2+ counter-ions on CMC thermal degradation in air. From the TG and DTG curves, thermal degradation of the samples occurred in three stages. During the second stage (200–410 °C) major degradation occurred, accompanied by a large weight loss. The 3D FTIR absorbance spectra and Gram-Schmidt curves of the evolved gases were obtained. In compounds CMC-Na and CMC-Ca, the initial degradation temperature is higher, the rate of CMC degradation increases, and the weight loss in the temperature range 200–410 °C decreases. These samples also catalyse the stable intermediate products in the temperature range 410–600 °C.

Structure analysis and thermal degradation characteristics of bio-based poly(propylene succinate)s obtained by using different catalyst amounts

Linear bio-based polyester polyols were prepared with the use of succinic acid and 1.3-propanediol (both with natural origin). As a catalyst was used tetraisopropyl orthotitanate (TPT). In order to determine the effect of various catalyst content on the thermal degradation characteristics, three different TPT amounts, as a 1.3-propanediol equivalent, were used, namely 0.1 mass% (PPS-0.1), 0.2 mass% (PPS-0.2) and 0.25 mass% (PPS-0.25). The reference polyol was prepared without catalyst employment (PPS-0.0). Fourier transform infrared spectroscopy was used to confirm molecular structure of the resulted polyols. The structure was also corroborated by 1H NMR measurements, what confirmed nonsignificant catalyst amount impact on the structure of the prepared polyester polyols. Differential scanning calorimetry was carried out for glass transition temperature and melting point determination. The thermogravimetric analysis allowed to observe high thermal stability both under inert and oxidative atmosphere. This analysis affirmed also that the catalyst content did not influence significantly on the thermal degradation characteristics of the prepared polyols.

Pyrolysis of Olive Pomace: Degradation Kinetics, Gaseous Analysis and Char Characterization

The kinetics of olive pomace pyrolysis and the characterization of the obtained products were studied. The thermal degradation characteristics of olive pomace were investigated using thermogravimetric analysis under nitrogen atmosphere. Five heating rate profiles were applied (5, 15, 20, 25 and 30 °C.min −1), with a final temperature of 600 °C which was maintained for 2 h. Two main stages of degradation were identified, corresponding to the degradation of the main compounds (hemicellulose, cellulose and lignin).The kinetic parameters were evaluated by using Kissinger–Akahira–Sunose and parallel reaction methods. The energy of activation was evaluated according to the conversion rate of olive pomace. The analysis of the gaseous products showed that the main pyrolysis gas products of biomass are: CO2 (122.6 mg g−1), CO (45.3 mg g−1), C3H8 (1.7 mg g−1), C3H6 (6 mg g−1) and CH4 (20.4 mg g−1). The characterization of pyrolytic char was performed using thermogravimetric analysis, BET and X-ray fluorescence (XRF) analyses. The textural properties of the biochar were found to correspond to an ultra-microporous solid with a high porous surface. The BET surface area measured using CO2 adsorption was 296 m2g−1 and the micorpore volume was 0.16 cm3g−1. Furthermore, XRF analysis indicated that Ca and K are the major mineral species in the char with non-negligible presence of P and Mg contents. These different characteristics may encourage its recovery for soil amendment.

Accelerated ageing and degradation characteristics of rigid polyurethane foam

The urgent need for revision of the normative test method (EN 253) for the lifetime prediction of district heating pipes requires a better understanding of the failure mechanisms involved. Therefore, various methods were used to study thermal degradation characteristics of rigid polyurethane (PUR) foam in both air and nitrogen atmosphere. Accelerated ageing in nitrogen caused insignificant changes, whereas ageing in air caused significant changes in weight, dimensions, chemical structure and cell gas composition, indicating importance of the thermo-oxidative type of degradation. A clear indication of the thermo-oxidative type of degradation was the formation of new carbonyl groups in PUR together with the loss of CH2 groups after ageing in air. Another result of ageing in air was the loss of pentane and cyclopentane, and the formation of some new volatile compounds in the cells of PUR foam. However, despite a large difference in degradation characteristics between the samples aged in air and in nitrogen, no significant difference in the flexural strength of PUR foam was recorded during the induction stage of the degradation process. Furthermore, it is shown that the significant drop in shear strength, which reflects the adhesion force between PUR foam and steel pipe, observed during the early stage of accelerated ageing of district heating pipes is not caused by thermo-oxidative degradation.

Fuel Recovery from Thermal Processing of Post-consumer Footwear Waste

ABSTRACTCurrently, almost 25 billion pairs of shoes are annually manufactured worldwide. Logically, a large amount of footwear waste is generated. Economically and environmentally acceptable disposal of the waste is needed. In the present work, fuel recovery from thermal processing of shoe waste is considered. Energetic content of shoe waste was estimated. Thermal degradation characteristics and distribution and yields of the products were analyzed. They were carried out using a macro scale, thermogravimetric analyzer and gas chromatography. It was found that the calorific value of the shoe waste was high (21 MJ/ kg). Analysis revealed that the pyrolysis of shoe waste at atmospheric pressure started around 100°C and finished at about 700°C. Three degradation temperature regions during pyrolysis of the shoe waste were recorded. Products of pyrolysing waste comprised solid residue (around 26%), liquid (around 34%) and gas fraction (around 40%). Product gases contained fractions of combustible components, i....

Decomposition Characteristics and Kinetics of Microalgae in N2 and CO2 Atmospheres by a Thermogravimetry

The thermal degradation characteristics of microalgae were investigated in highly purified N2 and CO2 atmospheres by a thermogravimetric analysis (TGA) under different heating rates (10, 20, and 40°C/min). The results indicated that the total residual mass in CO2 atmosphere (16.86%) was less than in N2 atmosphere (23.12%); in addition, the kinetics of microalgae in N2 and CO2 atmospheres could be described by the pseudo bicomponent separated state model (PBSM) and pseudo-multi-component overall model (PMOM), respectively. The kinetic parameters calculated by Coats-Redfern method showed that, in CO2 atmosphere, the apparent activation energy (E) of microalgae was between 9.863 and 309.381 kJ mol−1 and the reaction order (n) was varied from 1.1 to 7. The kinetic parameters (E,n) of the second stage in CO2 atmosphere were quite similar to those in N2 atmosphere.

인도네시아산 자원 내에 포함된 역청성 오일의 경질화를 위한 열분해 특성에 관한 연구

본 연구에서는 인도네시아 현지로부터 수급된 지층 자원에 포함된 역청성 오일의 경질화를 위하여 열분해 공정이 적용되었다. 이러한 자원 내에 포함된 역청성 오일에 대한 조성 및 기초성상을 조사하기 위하여 공업분석, 원소분석 등이 수행되었으며, 열중량분석을 통해 역청성 오일의 전환에 대한 열분해반응 기초특성이 조사되었다. 이러한 결과를 바탕으로 원료 내에 포함된 역청성 오일을 경질화하기 위하여 필요한 열분해 온도 등의 운전조건 범위가 선정되었으며, 실험실 규모의 고정층 반응기를 이용하여 반응온도에 따른 역청성 오일의 전환율 및 열분해 오일의 회수율을 확인하였다. <TEX>$550^{\circ}C$</TEX>에서 수행된 열분해 공정에서 원료 내 포함된 역청성 오일의 전환율은 약 21%였으며, 경질화된 열분해 오일의 회수율은 약 80%였다. In this study, the pyrolysis process was carried out in order to upgrade of heavy oil contained in the resources from Indonesia. In order to investigate the composition and basic properties of the heavy oil contained in the resources, the various analytical methods was used and then the TGA (thermogravimetric) method was especially used for the thermal degradation characteristics of heavy oil in the pyrolysis. From the results obtained from the various analytical methods, the reaction conditions such as the reaction temperature was collected for the pyrolysis process and the pyrolysis using the resources containing the heavy oil was conducted using the fixed-bed reactor under the various reaction conditions. Consequently, We found that the content of heavy oil contained in the resources was about 35% and the conversion of heavy oil and the recovery efficiency of thermal degradation oil were about 21 and 80%, respectively.

Combustion characteristics and kinetic parameter estimation of Lantana camara by thermogravimetric analysis

ABSTRACTLantana camara has the potential to be used as a feedstock for thermochemical conversion processes such as pyrolysis and gasification for heating, cooking purposes and to generate electricity. This study deals with the thermal degradation characteristics of L. camara and the estimation of kinetic parameters namely activation energy and frequency factor. The proximate analysis, ultimate analysis and heating values of L. camara wood were also studied. The experiments were conducted in a thermogravimetric analyzer from 30–670 °C in the atmosphere of air at different heating rates, namely 5, 10, 25 and 50 °C min−1. The thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA) curves indicated that the combustion of L. camara wood exhibited three distinct zones: removal of moisture, combustion of light volatiles and oxidation of char. The effect of heating rate on the combustion process was examined. The kinetic parameters were evaluated using different model free methods such as Kissinger, Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall and Friedman. The activation energy was calculated using the model free methods and the mean values were 105.83, 193.6, 184 and 197.8 kJ/mol.

Thermogravimetric and devolatilisation analysis for five plantation species: Effect of extractives, ash compositions, chemical compositions and energy parameters

Woody biomasses from five fast-growth plantations of Costa Rica were evaluated in relation to thermal degradation characteristics and devolatilisation rate (Drate) using thermogravimetric analysis (TGA). The relationship between TGA parameters and Drate with content of cellulose, lignin and extractives were established. The results indicate that during degradation, the five woody biomass types (Cupressus lusitanica, Dipterix panamensis, Gmelina arborea, Tectona grandis and Vochysia ferruginea) show different temperatures and residual mass, as well as different Drate of the polymers conforming them, indicating that each biomass type has unique pyrolysis characteristics. The difference in these parameters is influenced by extractives content, and a little effect is presented due to lignin content, cellulose content and ash composition. A greater amount of extractives decreases the degradation temperatures of the different biomass components, although the residual mass was scarcely affected and if so, a positive correlation was presented. Extractives also affected the Drate more significantly than cellulose, lignin and macro- or micro-nutrients contents. Moreover, the Drate of cellulose was more affected by the extractives content than was Drate of hemicellulose, indicating a higher degree of association of extractives with cellulose than hemicellulose. In this concern, the higher the amount of extractives, the lower the Drate of cellulose.

Pyrolysis of commingled waste textile fibers in a batch reactor: Analysis of the pyrolysis gases and solid product

ABSTRACTThe main object of this study was the investigation of the thermal recycling of commingled waste textile fibers, with the aim of the production of useful end products. Differential scanning calorimetry/Thermo gravimetric analysis (DSC/TGA) was applied to determine the thermal degradation characteristics of the commingled waste textile fibers and there are two peaks located at the temperature ranges of 299–360°C and 399–500°C. Commingled waste fiber was pyrolyzed in a nitrogen atmosphere in relation to three different temperatures (500, 600, and 700°C), heating rates (25 and 50°C min−1), and retention times (15 and 30 min). The effect of the experimental conditions such as pyrolysis temperature, heating rates, and retention time on the formation of char and gas--liquid products was investigated and the product yields were determined from the rate of the weight loss. The highest conversion rate 82.9 wt.% liquid--gas product and 17.1 wt.% char product was achieved at 700°C. Pyrolysis gases were taken for every 7, 15, and 25 min and were analyzed for major components such as CO, CO2, CH4, and H2 by gas chromatography. The pyrolysis char called as carbon black derived from the pyrolysis of commingled waste textile fibers was analyzed for a range of properties, including the elemental analysis, moisture content, ash content, calorific value, and trace metal analysis.

Crystallization, mechanical properties and thermal stability of cockleshell-derived CaCO3 filled polypropylene

This study discusses the potential of utilizing waste cockleshell derived-CaCO3 (CS) as filler in polypropylene (PP). Mineral fillers were prepared from cockleshell-derived CaCO3 and used to fill polypropylene. The composites were prepared by melt blending and fabricated by injection and compression molding techniques. The effects of filler on crystal structure, crystallization and thermal degradation characteristics of filled polypropylene composites were elucidated. The cockleshell filler promoted the formation of the β-crystalline phase in PP, which improved the rigidity and toughness of the composites. However, stearic acid treatments on the filler would significantly affect the nucleation process and therefore hindered crystallization. Acceleration in thermal degradation of PP was also noted with increasing filler loading.