Thermal Degradation Behavior of Epoxy Resin Containing Modified Carbon Nanotubes

Via the surface-grafting of carbon nanotubes (CNTs) with a silicon-containing flame retardant (PMDA), a novel flame retardant CNTs-PMDA was synthesized. The flame retardancy was tested by cone calorimeter. Compared with pure epoxy resin, the total heat release (THR) and peak heat release rate (PHRR) of epoxy resin containing CNTs-PMDA were significantly reduced, by 44.6% and 24.6%, respectively. Furthermore, thermal degradation behavior of epoxy resin based composite was studied by the thermogravimetric analysis with differences in heating rates. The kinetic parameters of the thermal degradation for epoxy resin composites were evaluated by the Kissinger method and Flynn-Wall-Ozawa method. The results suggested that activation energy values of epoxy resin containing CNTs-PMDA in thermal degradation process were higher than those of pure epoxy resin in the final stage of the thermal degradation process, which was closely related to the final formation of char layer residues. Finally, the results from Dynamic mechanical thermal analysis (DMTA) and Scanning electron microscopy (SEM) measurements exhibited that the functionalization of CNTs with PMDA obviously improved the dispersion of CNTs in the epoxy resin matrix.

Effect of Degradation Time on Carotene Content in Crude Carotene Extract of Carrot for the Formation of its Derivative Aromatic Compounds

Background: The difference in degradation time on the formation of carotene’s derivative aromatic compounds [β-ionone and dihydroactinidiolide (dhA)] due to thermal degradation process of carotenes in crude carotenoid extract of carrot was studied. Methods: β-ionone and dhA formation and that of carotenes degradation during thermal degradation (T=140°C) was observed periodically for 4 h. The constant oxygen supply during degradation was maintained at approx. 7 L/h. Result: The formation of β-ionone and dhA accumulated significantly with increasing duration of the degradation process. The maximum formation of β-ionone and dhA could be estimated with the pattern of carotenes degradation. After 4 h of degradation, more than 80% carotene has degraded. It can be concluded that the degradation process of crude carotene extract from carrots at temperature of 140°C will result in a maximum carotene degradation process when the degradation process is carried out for 5 h.

Potentialities in the performance of coating mortars through the addition of sewage sludge ash

Through environmental policies that provide a gradual discussion about the destination of the tailings produced in the most diverse industrial sectors, the sewage sludge is emphasized by the problematic destination arising from the amount of toxic compounds that compose it, compromising its disposal. Aiming to fulfill the sustainable role through the creation of mechanisms that favor the ecological coexistence between environment and human beings, it is possible through the use of construction materials, considered as conventional, the use of calcined sewage sludge as an enhancer of the properties of matrix materials cement, significantly improving its performance against mechanical stresses and degradation mechanisms. Based on the need to implement measures to mitigate environmental impacts through the production of eco-efficient materials, the ashes of sanitary sewage sludge as a partial substitute for Portland cement have now been used as an input in coating mortars. This substitution focuses on reducing the large volume of sludge generated by the Sewage Treatment Plants, as well as on the reduction in the consumption of cement, a large CO2 generator during its manufacturing process. It was observed that through the use of this calcined by-product applied in mortars, a relevant physical-mechanical performance in cementitious materials is ratified, that in comparison to the material without the use of it, better results are observed, resulting from the reactivity conferred to the sludge after the thermal degradation process, making it a pozzolana.

Thermal Oxidative and Non-Oxidative Degradation Behaviour of Afuze Coal

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.

Thermal degradation of the anthocyanins extracts from jabuticaba peels and red cabbage leaves

Anthocyanins are phenolic compounds with tinctorial capacity. Their successful extraction and purification depends on information associated with their thermal stability. This work presents a study on the degradation kinetics of the anthocyanins in the peels of the jabuticaba fruits and the leaves of red cabbage through assays performed at different temperatures (ranging from 323.15 K to 363.15 K) and degradation times (up to 10 hours for jabuticaba and 30 hours for red cabbage). Total monomeric anthocyanins were determined through the pH differential method. Regarding the extraction, it was observed a larger quantity of anthocyanins from red cabbage extracts, with an average value of 1.3774 mg‧gdb-1, when compared to jabuticaba extracts, with an average value of 1.0479 mg‧gdb-1. The results suggest that the anthocyanins in the red cabbage leaves are much more thermally stable than the anthocyanins in the jabuticaba peels. The experimental assays suggest that the thermal degradation reaction proceeds according to a first-order kinetics model for the anthocyanins in both sources under study. The experimental values were treated according to their thermodynamic relations, which indicated that the thermal degradation process of the evaluated anthocyanins is endothermic and not spontaneous, with similar values of 64.8 kJ‧mol-1 for the red cabbage and 70.2 kJ‧mol-1 for the jabuticaba.

Study of Zeolite Usage in Thermal Degradation Process of Polypropylene Pyrolysis

Plastics materials have been an integral part in people’s daily life due to their high elasticity, formability and lightweight characteristics which are suitable for many products. However, exponentially growth of plastics waste leads to heavy environmental problems due to the plastics nature which is not easily degradable. One of solution to alleviate environmental problems due to plastics waste is to use pyrolysis method to burn plastics waste and convert them into lighter hydrocarbon which can be used as a source of energy. In this final project, the addition of zeolite catalyst in pyrolysis process of Polypropylene plastic waste has been studied in the terms of energy activation. Isoconversional Friedman and Flynn-Wall-Ozawa methods were used. The results may suggest that the role of zeolite as catalyst is pronounced only in the early stage of pyrolysis process. Keywords: plastics waste, Polypropylene, Zeolite, Friedman, Flynn-Wall-Ozawa

Thermal pyrolysis characteristics and kinetic analysis of nanofibrillated cellulose/graphene oxide composites

The fabrication process determines the microstructure and physical properties of material to some extent. In this study nanofibrillated cellulose /graphene oxide (NFC/GO) composites were fabricated by casting and evaporation methods, respectively. The microstructure and thermostability of the composites were investigated. The composites fabricated by the casting method had more uniform layered microstructure than those made by the evaporation method. The thermogravimetry analysis indicated that in the stage of 100 to 220 °C diffusion, the mechanisms of the Ginstling-Brounstein equation (D4) and the one-way transport equation (D1) can be regarded as the most suitable thermal pyrolysis reaction models for the composites made by the casting method and the evaporation method, respectively. However, in the stage of 220 to 380 °C, the two types of composites showed totally different thermal pyrolysis mechanisms. The results manifested that forming methods could indeed affect the microstructure and thermal degradation process of composites.

Thermal Degradation Process of Semi-Synthetic Fuels for Gas Turbine Engines in Non-Aeronautical Applications

This article concerns the issue of thermal degradation process of fuels, important from the perspective of the operation of turbine engines, especially in the context of new fuels/bio-fuels and their implementation. The studies of the kerosene-based jet fuel (Jet A-1) and its blends with synthetic components manufactured according to HEFA and ATJ technology, were presented. Both technologies are currently approved by ASTM D7566 to produce components to be added to turbine fuels. Test rig investigations were carried out according to specific methodology which reflects the phenomena taking place in fuel systems of turbine engines. The mechanism of thermal degradation process was assessed on the basis of test results for selected properties, IR spectroscopy and calculation of activation energy. The results show that with the increase of the applied temperature there is an increment of the content of solid contaminants, water and acid for all tested fuels. Thermal degradation process is different for conventional jet fuel when compared to blends, but also semi-synthetic fuels distinguished by different thermal stability depending on a given manufacturing technology.