Dynamic Heating Rate Research Articles

Pyrolysis characteristics and kinetic investigation of waste groundnut shells using thermogravimetric analyzer, Py-FTIR, and Py-GC-MS

The objective of the present study was to investigate the bioenergy and resource recovery potential of groundnut shells (GNS) through pyrolysis. The release of vapours at short time scales and their composition were investigated using analytical pyrolysis coupled with Fourier transform infrared (FTIR) spectroscopy and gas chromatography/mass spectrometry (GC/MS). The thermal decomposition behaviour and kinetic evaluation were carried out using a thermogravimetric analyzer (TGA). Five iso-conversional models and master plots method were utilized to explore the kinetic parameters and reaction mechanism at dynamic heating rates (10, 20, and 30 °C min−1). X-ray fluorescence spectroscopy (XRF) was employed to detect the ash composition, which is essential to evaluate the slagging and fouling potential of the biomass when used for bioenergy. TG data revealed three distinct stages of decomposition, while an immense amount of biomass disruption was observed at a higher heating rate (30 °C min−1). Further, the average apparent activation energy of pyrolysis determined using KAS, ST, DAEM, and VZ were 223.26, 214.57, 207.97, and 117.24 kJ mol−1, respectively. The extreme emission of carbon dioxide and carbonyl compounds was discovered through Py-FTIR. The increased formation of hydrocarbons (14.22–34.26%), alcohols (1.41–9.43%), and reduction in phenols (19.13–18.67%) at different temperatures (450, 550, and 650 °C) were validated by Py-GC-MS. Overall, the findings demonstrate that GNS is a promising feedstock for pyrolysis to produce valuable fuel molecules and chemicals.

Kinetic Analysis of the Reaction between Tannic Acid (TA) and L-Lysine Diisocyanate (LDI) Systems

The kinetics of the synthesis of green polyurethane from the reaction between tannic acid (TA) and L-lysine diisocyanate (LDI) were investigated using the differential scanning calorimeter (DSC) technique and dynamic rheological tests. The evaluation of the reaction behavior of the prepared samples was carried out using nonisothermal conditions at dynamic heating rates of 5, 10, 15, and 20°C/min. The evolution of the activation energy with conversion was computed through the five isoconversional methods of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose (KAS), the Ozawa-Flynn-Wall method (OFW), Friedman (FR), Starink, and Vyazovkin. The average activation energy calculated from these methods was estimated at 46.5, 46.8, 47.2, 47.3, and 51.4 KJ/mol, respectively. The preexponential factor was evaluated at 5.04 × 10 5 1/s. The overall reaction order ( n + m ) was also found to be around 1.8912. The results of the combination of the model-free method and model-fitting approach exhibited that the reaction mechanism was an autocatalytic type, implying the autocatalytic effect of the urethane groups formed during the reaction. The obtained kinetic for TA/LDI was verified through its good agreement with the experimental data. Moreover, the results found from the isothermal rheological test show that with increasing temperature, the gelation time decreases.

Thermo-catalytic pyrolysis of Azadirachta indica seeds over CaO and CuO: Pyrolysis kinetics, impact of catalysts on yield, fuel properties and its chemical compositions

Pyrolysis oil and distribution is still in the incipient stages, though it is a potential source of energy and valueable chemicals. The current work focused on the kinetics study and thermo-catalytic pyrolysis of Azadirachta indica seeds (AZI) over CaO and CuO. The kinetic behaviour of AZI is studied in a TGA under an inert atmosphere at dynamic heating rates (10, 20 and 30 °C min−1) using Starink method (ST) and Vyazovkin model (VM). Further, AZI were pyrolyzed in a semi-batch tubular reactor at 500 °C, 50 °C min−1 heating rate and 100 mL min−1 nitrogen flow rate at 20 wt% catalyst loading. The biomass and pyrolysis liquid were characterised via proximate analysis, elemental analysis, thermal stability, FTIR, viscosity, density, acidity, moisture content, GC-MS etc. Kinetic analysis of AZIs confirmed that biomass decomposition takes place in a multifaceted route, and the activation energy is associated with conversion and temperature. Thermal pyrolysis exhibited 39.53 wt% liquid yields; however, introducing 20 wt% catalyst has improved the yield to 46.53 wt% and 45.36 wt% for CaO and CuO, respectively. The findings of the thermal and catalytic pyrolytic oil demonstrated that the addition of catalysts significantly enhanced the properties of pyrolytic oil by lowering viscosity and oxygen content while raising heating value and acidity. Finally, GC-MS results displayed that the use of catalysts resulted in a considerable decline in the proportion of oxygenated compounds, acids, and phenols and an increase in the proportion of hydrocarbons, aldehydes and alcohols.

Pyrolysis of low-value waste Trapa natans peels: An exploration of thermal decomposition characteristics, kinetic behaviour, and pyrolytic liquid product

The current work seeks to maximise the bio-oil yield by optimizing the experimental conditions and process parameters for the pyrolysis of water chestnut peels (WCP). The pyrolysis process was carried out in a stainless steel reactor to produce the pyrolysis product. The kinetic analysis was carried out using the model-free techniques such as Ozawa-Flynn-Wall (OFW), Vyazovkin (VZK), and Kissinger-Akahira-Sunose (KAS), while the thermal degradation profile was measured using a thermogravimetric analyzer (TGA) at dynamic heating rates (10, 15, and 20 °C min−1). Additionally, Gas Chromatography (GC) was used to study the non-condensable gases, whereas biochar was characterized according to its physicochemical properties. The results of the kinetic analysis exhibited that utilising the KAS, OFW, and VZK, the average apparent activation energies of WCP were obtained to be 344.37, 337.10, and 325.10 kJ mol−1, respectively. The thermal pyrolysis results revealed that the highest bio-oil yield (42.20 wt%) was achieved at 600 °C temperature, 25 °C min−1 heating rate, and 6 cm bed height. According to GC results, the hydrocarbon levels increased as the temperature increased. Biochar's suitability for usage in various industrial applications was validated by the findings of its characterization.

Pyrolysis of low-value waste miscanthus grass: Physicochemical characterization, pyrolysis kinetics, and characterization of pyrolytic end products

The current study explored the bioenergy potential of waste miscanthus grass (WMG). The kinetic study of WMG was evaluated via two model-free methods, in a thermogravimetric analyzer (TGA), at dynamic heating rates under an inert ambiance. The pyrolysis was performed in a semi-batch fixed bed reactor at 500 oC, 80 oC min heating rate, and 1 mm particle size. The evolution of hot vapours during pyrolysis was explored using a TGA-FTIR analyzer. Finally, the bio-oil and biochar were characterized by their physicochemical properties. The kinetic results established that WMG followed a multi-step decomposition process, and the average activation energy gained from KAS and ST was found to be 197.66 and 179.64 kJ mol-1, respectively. TGA-FTIR study revealed the foremost release of carbon dioxide (28.22%), followed by a carbonyl (25.40%), and ether (19.12%). Further, the pyrolysis of WMG yielded 29.32 wt% of bio-oil at the optimized condition whereas, physicochemical results of bio-oil established; 65.16% carbon content, 26.16 MJ kg-1 HHV, 34.15 cP viscosity, and 812 kg m-3 density. GC-MS study of bio-oil confirmed the maximal release of hydrocarbons and phenols. Finally, characterization results of miscanthus grass biochar (MGB) demonstrated an excellent feedstock for industrial and domestic applications.

Elucidating the bioenergy potential of raw, hydrothermally carbonized and torrefied waste Arundo donax biomass in terms of physicochemical characterization, kinetic and thermodynamic parameters

The present investigation aimed to understand the pyrolysis kinetic behavior of raw Arundo donax (Raw-AD), hydrothermally carbonized Arundo donax (HTC-AD), and torrefied Arundo donax (TOR-AD) in a thermogravimetric analyzer at dynamic heating rates. The physicochemical characterization analysis revealed that fuel properties have been enhanced after hydrothermal carbonization and torrefaction. The characterization techniques such as FE-SEM, EDX, FTIR, and XRD have been used to investigate the biomass surface morphology, inorganic elements, functional groups, and crystallinity. The kinetic parameters were calculated using the model-free methods of Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), and Vyazovkin (VZK), whereas Criado's z(α) master plot was used to elucidate the reaction mechanism. The average activation energy was obtained to be 259.11, 262.53, and 250.13 kJ/mol for Raw-AD, 115.31, 110.39, and 107.26 kJ/mol for HTC-AD, and 243.46, 242.68, and 233.79 kJ/mol for TOR-AD using OFW, KAS, and VZK method respectively. The thermodynamic analysis divulged that pyrolysis proceeded through various reaction mechanisms.

Sensitivity of the Southern Hemisphere circumpolar jet response to Antarctic ozone depletion: prescribed versus interactive chemistry

Abstract. Southern Hemisphere lower-stratospheric ozone depletion has been shown to lead to a poleward shift of the tropospheric jet stream during austral summer, influencing surface atmosphere and ocean conditions, such as surface temperatures and sea ice extent. The characteristics of stratospheric and tropospheric responses to ozone depletion, however, differ among climate models depending on the representation of ozone in the models. The most appropriate way to represent ozone in a model is to calculate it interactively. However, due to computational costs, in particular for long-term coupled ocean–atmosphere model integrations, the more common way is to prescribe ozone from observations or calculated model fields. Here, we investigate the difference between an interactive and a specified chemistry version of the same atmospheric model in a fully coupled setup using a nine-member chemistry–climate model ensemble. In the specified chemistry version of the model the ozone fields are prescribed using the output from the interactive chemistry model version. We use daily resolved ozone fields in the specified chemistry simulations to achieve a very good comparability between the ozone forcing with and without interactive chemistry. We find that although the shortwave heating rate trend in response to ozone depletion is the same in the different chemistry settings, the interactive chemistry ensemble shows a stronger trend in polar cap stratospheric temperatures (by about 0.7 K decade−1) and circumpolar stratospheric zonal mean zonal winds (by about 1.6 m s−1 decade−1 as compared to the specified chemistry ensemble. This difference between interactive and specified chemistry in the stratospheric response to ozone depletion also affects the tropospheric response. However, an impact on the poleward shift of the tropospheric jet stream is not detected. We attribute part of the differences found in the experiments to the missing representation of feedbacks between chemistry and dynamics in the specified chemistry ensemble, which affect the dynamical heating rates, and part of it to the lack of spatial asymmetries in the prescribed ozone fields. This effect is investigated using a sensitivity ensemble that was forced by a three-dimensional instead of a two-dimensional ozone field. This study emphasizes the value of interactive chemistry for the representation of the Southern Hemisphere stratospheric-jet response to ozone depletion and infers that for periods with strong ozone variability (trends) the details of the ozone forcing could also have an influence on the representation of southern-hemispheric climate variability.

Radiative Relaxation Time Scales Quantified from Sudden Stratospheric Warmings

Abstract Sudden stratospheric warmings (SSWs) are impressive events that occur in the winter hemisphere’s polar stratosphere and are capable of producing temperature anomalies upward of +50 K within a matter of days. While much work has been dedicated toward determining how SSWs occur and their ability to interact with the underlying troposphere, one underexplored aspect is the role of radiation, especially during the recovery phase of SSWs. Using a radiative transfer model and a heating rate analysis for distinct layers of the stratosphere averaged over the 60°–90°N polar region, this paper accounts for the radiative contribution to the removal of the anomalous temperatures associated with SSWs. In total 17 events are investigated over the 1979–2016 period. This paper reveals that in the absence of dynamical heating following major SSWs, longwave radiative cooling dominates and often results in a strong negative temperature anomaly. The polar winter stratospheric temperature change driven by the radiative cooling is characterized by an exponential decay of temperature with an increasing e-folding time of 5.7 ± 2.0 to 14.6 ± 4.4 days from the upper to middle stratosphere. The variability of the radiative relaxation rates among the SSWs was determined to be most impacted by the initial temperature of the stratosphere and the combined dynamic and solar heating rates following the onset of the events. We also found that trace-gas anomalies have little impact on the radiative heating rates and the temperature evolution during the SSWs in the mid- to upper stratosphere.

Thermal behaviour, kinetics and fast pyrolysis of Cynodon dactylon grass using Py-GC/MS and Py-FTIR analyser

Cynodon dactylon (DG) is a biological resource available in abundance across the world; and has the capability to yield sustainable renewable fuels and fine chemicals. The present study explored the bioenergy potential of DG biomass by evaluating its physicochemical properties, pyrolysis characteristics, and kinetic behaviouer with thermodynamic analysis (TD) for the first time. The physicochemical outcome established its bioenergy potential towards sustainable energy production. The thermal decomposition study of DG biomass was carried out in a thermogravimetric analyser (TGA) at dynamic heating rates (10, 30 and 50 °C min−1), under nitrogen atmosphere while Py-GC–MS was executed to understand the pyrolysis behaviour. The thermal decomposition profile of the DG biomass established multistage degradation, which is linked to the diverse components in its structure. The average apparent kinetic energy was found to be 208.89, 220.43, 211.90, 213.66, 214.28 and 192.30 kJ mol−1 for Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW), Friedman (FM), Starink (ST), Distributed Activation Energy Model (DEAM), and Vyazovkin (VZ). Py-GC–MS results revealed that formation of phenolics, aromatic hydrocarbons and ketones in the temperature range 450–650 °C were increased while formation of cyclopentanones, acids, esters and other oxygenated compounds were reduced. Finally, Py-FTIR study confirmed that the majority of functional groups generated in the range of 4 −15 s.

Poly(lactic acid) phase transitions in the presence of nano calcium carbonate: Opposing effect of nanofiller on static and dynamic measurements

The effect of stearic acid-coated nano calcium carbonate (NCC) on transitions and chain mobility of poly(lactic acid) (PLA) was investigated. Dispersion state of NCC in polymeric matrix was explored using scanning electron microscopy and surface tension component measurements. Trends of PLA transitional phenomena were investigated using the results of dynamical mechanical analysis (DMA) and differential scanning calorimetry (DSC) in the nanocomposite systems based on PLA and NCC. In addition, two types of crystal structures and decreasing the glass transition temperature were distinguished using temperature-modulated DSC (TMDSC). Higher melting points of polymer crystals were found in TMDSC experiments due to low and dynamic heating rate compared to the conventional DSC. Dynamics of polymer chains, affected by NCC, were quantified using cooperativity length, ξ α, and the number of relaxing structural units, Nα, in the glass transition region. NCC particles hindered the cooperative motion of polymer chains at glass transitions and crystallization in TMDSC measurements, whereas the DMA results indicated that NCC particles may act as lubricant and simplified chain mobility.

Indirect Trajectory Optimization for Mars Entry with Maximum Terminal Altitude

In this paper, a novel computational optimization framework is presented for the design of Mars entry trajectories with maximum terminal altitude. The second-order path constraints included in the framework are the constraints on the dynamic pressure, aerodynamic acceleration, and heat rate. The framework is built on the so-called Pontryagin’s maximum principle, exact penalty method, and simplicial homotopy method. In this framework, the exact penalty method is used to transform the original path-constrained maximum terminal altitude problem into an equivalent path-unconstrained maximum terminal altitude problem. A novel one-parameter penalty function, which is continuous and differentiable at any point, is introduced to penalize the performance index. Then, the resulting path-unconstrained maximum terminal altitude problem is converted to a two-point boundary value problem based on Pontryagin’s maximum principle. Several auxiliary problems are properly constructed such that the simplicial homotopy method can be applied to address the problem of initial guess. By doing so, a ballistic entry trajectory can be taken as an initial guess for the solution of the path-unconstrained maximum terminal altitude problem. Finally, numerical results are presented to demonstrate the effectiveness of the proposed computational optimization framework.

Dynamics of Orographic Gravity Waves Observed in the Mesosphere over the Auckland Islands during the Deep Propagating Gravity Wave Experiment (DEEPWAVE)

Abstract On 14 July 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE), aircraft remote sensing instruments detected large-amplitude gravity wave oscillations within mesospheric airglow and sodium layers at altitudes z ~ 78–83 km downstream of the Auckland Islands, located ~1000 km south of Christchurch, New Zealand. A high-altitude reanalysis and a three-dimensional Fourier gravity wave model are used to investigate the dynamics of this event. At 0700 UTC when the first observations were made, surface flow across the islands’ terrain generated linear three-dimensional wave fields that propagated rapidly to z ~ 78 km, where intense breaking occurred in a narrow layer beneath a zero-wind region at z ~ 83 km. In the following hours, the altitude of weak winds descended under the influence of a large-amplitude migrating semidiurnal tide, leading to intense breaking of these wave fields in subsequent observations starting at 1000 UTC. The linear Fourier model constrained by upstream reanalysis reproduces the salient aspects of observed wave fields, including horizontal wavelengths, phase orientations, temperature and vertical displacement amplitudes, heights and locations of incipient wave breaking, and momentum fluxes. Wave breaking has huge effects on local circulations, with inferred layer-averaged westward flow accelerations of ~350 m s−1 h−1 and dynamical heating rates of ~8 K h−1, supporting recent speculation of important impacts of orographic gravity waves from subantarctic islands on the mean circulation and climate of the middle atmosphere during austral winter.

Thermal stability of cellulose nanomaterials and their composites with polyvinyl alcohol (PVA)

This study investigates the thermal stability of composites composed of polyvinyl alcohol (PVA) reinforced with biodegradable fillers: cellulose nanocrystals (CNC) or cellulose nanofibrils (CNF). Combinations of PVA with CNC and PVA with CNF at 2, 4, 6, and 8 % cellulose by weight underwent several different thermogravimetric analysis (TG) heating programs—constant heating rate, isothermal, and high resolution with a dynamic heating rate. The starting materials (PVA pellets, PVA film, aqueous CNC at 11.8 % solids, and aqueous CNF at 3 % solids) were also tested in the TG after drying. Temperatures at the onset of degradation and at maximum degradation for the principal pyrolysis stage were quantified. Kinetic parameters (activation energy, pre-exponential factor) were calculated using the Flynn–Wall–Ozawa (FWO) method. CNC or CNF incorporation in the PVA matrix did not markedly shift temperatures at the onset of degradation or at maximum degradation for the major stage of pyrolysis, compared to neat PVA. However, the inclusion of nanocellulose lowered the maximum rate of degradation, with larger reductions at higher filler contents. A larger portion of the composites’ original mass remained intact following the major degradation peak. Incorporation of CNF in composites with PVA produced films with activation energies higher than the activation energy of neat PVA film.

Radiative and Dynamical Influences on Polar Stratospheric Temperature Trends

Abstract Radiative and dynamical heating rates control stratospheric temperatures. In this study, radiative temperature trends due to ozone depletion and increasing well-mixed greenhouse gases from 1980 to 2000 in the polar stratosphere are directly evaluated, and the dynamical contributions to temperature trends are estimated as the residual between the observed and radiative trends. The radiative trends are obtained from a seasonally evolving fixed dynamical heating calculation with the Parallel Offline Radiative Transfer model using four different ozone datasets, which provide estimates of observed ozone changes. In the spring and summer seasons, ozone depletion leads to radiative cooling in the lower stratosphere in the Arctic and Antarctic. In Arctic summer there is weak wave driving, and the radiative cooling due to ozone depletion is the dominant driver of observed trends. In late winter and early spring, dynamics dominate the changes in Arctic temperatures. In austral spring and summer in the Antarctic, strong dynamical warming throughout the mid- to lower stratosphere acts to weaken the strong radiative cooling associated with the Antarctic ozone hole and is indicative of a strengthening of the Brewer–Dobson circulation. This dynamical warming is a significant term in the thermal budget over much of the Antarctic summer stratosphere, including in regions where strong radiative cooling due to ozone depletion can still lead to net cooling despite dynamical terms. Quantifying the contributions of changes in radiation and dynamics to stratospheric temperature trends is important for understanding how anthropogenic forcings have affected the historical trends and necessary for projecting the future.

Improving mechanical and thermal properties of TiO2-epoxy nanocomposite

Abstract TiO2-epoxy nanocomposites were fabricated by using an innovative ultrasonic dual mixing process (UDM) process consists of ultrasonic mixing with simultaneous impeller stirring. TiO2 nanoparticles were used as reinforcement in epoxy resin with weight percentages 5, 10 and 15 respectively. Mechanical properties of each group of composite material were identified using tensile and dynamic mechanical measurements. The effect of TiO2 nanoparticles addition on dynamical mechanical properties of epoxy matrix in the terms of storage modulus and tanδ value with respect to the temperature at a dynamic heating rate of 2 °C/min were studied. The dispersion condition of TiO2 content in epoxy matrix has been thoroughly investigated by using field emission scanning electron microscopy (FESEM) analysis. Tensile tests and thermal gravimetric analysis (TGA) were performed on each group of TiO2-epoxy composite to determine their tensile strength, toughness and thermal stability.

Characterization of kiln feed limestone by dynamic heating rate thermogravimetry

Quicklime is a product rich in calcium oxide produced in industrial kilns. The process involves thermal decomposition of minerals with high content of calcium carbonate. The kiln feed properties vary with the geological formation from where the mineral is quarried or mined. Characterization of feed properties is necessary to achieve an optimized kiln production. In this work the decomposition of four different types of calcite ore was investigated by comparing conventional constant heating rate and dynamic heating rate thermogravimetric methods.The conclusion of this work is that the conventional method always “overshoots” the calcination temperature when continuously heating during calcination compared to the dynamic rate method that resembles the kiln by holding temperatures constant during the calcination event. This justifies the used of the dynamic rate method. By a correct experimental parameter setup the dynamic rate method can be adapted for individual kilns and feed fractions, giving new additional value to the kiln operator and increasing the high value use of limestone deposits. This new method to characterize calcination properties of kiln feed materials can be utilized in normal kiln operations and when developing new mixes of different quality limestone. The results show differences when comparing the methods and different materials even though CaCO3 is present only as calcite. In addition, the dynamic rate method is faster than the conventional method. Besides quicklime production the method can also be applied in other industries calcining limestone, such as cement clinker production.

Thermal behaviour of erythromycin-active substance and tablets

The application of thermal methods is of great importance in the solution of pharmaceutical problems, such as the control of raw materials, the determination of purity, the qualitative and quantitative analysis of drug formulation, tests of thermal stability and compatibility, the determination of kinetic parameters etc. The evaluation of thermal stability in the solid state is mostly made by analyzing their decomposition under isothermal and non-isothermal conditions. This study reports the study on the thermal behaviour of erythromycin-active substance and tablets, respectively, the determination of the kinetic parameters for the decomposition process under non-isothermal conditions. For the determination of kinetic parameters from the TG/DTG curves, were utilized the following methods: Friedman isoconversional, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Li–Tang, and Kissinger, respectively, a dynamic nitrogen atmosphere and different heating rates: 2.5, 5, 7.5, 10, and 15 °C min−1. Thermoanalytical curves showed that the active substance is thermally more stable than the tablets and the values of activation energy indicate a considerable thermal stability of active substance. The decrease in stability was attributed to the presence of excipients.

Ionosphere/thermosphere heating determined from dynamic magnetosphere-ionosphere/thermosphere coupling

[1] Ionosphere/thermosphere heating driven by magnetospheric convection is investigated through a three-fluid inductive (including Faraday's law) approach to describing magnetosphere-ionosphere/thermosphere coupling, for a 1-D stratified ionosphere/thermosphere in this initial study. It is shown that the response of the ionosphere/thermosphere and thus the heating is dynamic and height-dependent. The heating is essentially frictional in nature rather than Joule heating as commonly assumed. The heating rate reaches a quasi-steady state after about 25 Alfvén travel times. During the dynamic period, the heating can be enhanced and displays peaks at multiple times due to wave reflections. The dynamic heating rate can be more than twice greater than the quasi-steady state value. The heating is strongest in the E-layer but the heating rate per unit mass is concentrated around the F-layer peak height. This implies a potential mechanism of driving O+ upflow from O+ rich F-layer. It is shown that the ionosphere/thermosphere heating caused by the magnetosphere-ionosphere coupling can be simply evaluated through the relative velocity between the plasma and neutrals without invoking field-aligned currents, ionospheric conductance, and electric field. The present study provides understanding of the dynamic magnetosphere-ionosphere/thermosphere coupling from the ionospheric/thermospheric view in addition to magnetospheric perspectives.

A new Schiff base epoxy oligomer resin: Synthesis, characterization, and thermal decomposition kinetics

AbstractOligo{2,2′‐{1,4‐phenylenebis[nitrilomethylylidene]}bis(6‐methoxyphenol)} (OPNMMP) was synthesized from o‐vanillin and p‐phenylene diamine by oxidative polycondensation with NaOCl in an aqueous alkaline. Then, a new Schiff Base epoxy oligomer resin, OPNMMP–epichlorohydrine (EPC), was produced with EPC. The structures of the resulting compounds were confirmed by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, 1H‐NMR, and 13C‐NMR. Further characterization processes were preformed by thermogravimetry (TG)–differential thermal analysis, gel permeation chromatography, and solubility testing. Also, the kinetics of the thermal decomposition of OPNMMP–EPC were investigated by thermogravimetric analysis. The TG curves showed that the thermal decomposition of OPNMMP–EPC occurred in one stage. The kinetic parameters related to the decomposition kinetics of OPNMMP–EPC were obtained from TG curves with the following methods: Friedman, Flynn–Wall–Ozawa, Kissinger, invariant kinetic parameter, and Coats–Redfern (CR), under an N2 dynamic atmosphere and different heating rates (5, 10, 15, and 20°C/min). The mechanism function and pre‐exponential factor were also determined by a master plots method. The apparent activation energies of the thermal decomposition were calculated from these methods for OPNMMP–EPC. The analysis of the results obtained by the CR and master plots methods showed that the decomposition mechanism of OPNMMP–EPC in N2 was a deceleration‐type mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Study on thermal decomposition of calix[6]arene and calix[8]arene

Thermal decomposition kinetics of calix[6]arene (C6) and calix[8]arene (C8) were studied by Thermogravimetry analysis (TG) and Differential thermal analysis (DTA). TG was done under static air atmosphere with dynamic heating rates of 1.0, 2.5, 5.0, and 10.0 K min−1. Model-free methods such as Friedman and Ozawa–Flynn–Wall were used to evaluate the kinetic parameters such as activation energy (Ea) and pre-exponential factors (ln A). Model-fitting method such as linear regression was used for the evaluation of optimum kinetic triplets. The kinetic parameters obtained are comparable with both the model-free and model-fitting methods. Within the tested models, the thermal decomposition of C6 and C8 are best described by a three dimensional Jander’s type diffusion. The antioxidant efficiency of C6 and C8 was tested for the decomposition of polypropylene (PP).