The thermal and structural properties of nitrazepam and citric acid have been studied alone and in the corresponding binary mixture, using differential scanning calorimetry (DSC), Fourier Transform Infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The thermodynamic study of the binary mixture nitrazepam-citric acid was made by DSC analysis. The mixtures were obtained by mechanosynthesis. For the binary mixtures, an eutectic reaction was observed in all DSC curves at 396 K. The phase diagram and Tamman's plot suggest an eutectic composition at the ≈0.4 molar fraction of nitrazepam. XRD and FTIR have been used as complementary methods to demonstrate that the obtained compound is eutectic. The solubility tests have been performed on the eutectic composition and nitrazepam. The results showed that the parameter influencing the solubility of nitrazepam is the acidic character of the sample.

Abstract not available

Flame retardant and antibacterial applications of wool are attracting increasing scientific attention. Herein, we report a facile method to deposit a zinc-based coating on the surfaces of wool fabric and fabricate functional fabrics with flame retardant and antibacterial properties. The wool fabrics with 9.9 % weight add-on could reach a limit oxygen index value of 33.7%. Compared to the control sample, the coated sample exhibited better fire safety properties, with peak heat release rate and total smoke production values decreased by 46.5% and 33.7% during a cone calorimeter test. The obtained wool fabrics also demonstrated excellent antibacterial properties, with Staphylococcus aureus and Escherichia coli killing rates of 99.4% and 96.9%, respectively. These results proved that the treated wool samples had excellent flame retardancy and antibacterial properties. Additionally, the flame-retardant coating had minor negative effects on the whiteness and strength of the wool fabrics.

One of the major issues in polymer recycling nowadays is related to the impact of biodegradable polymers and/or nanoparticles’ presence on the thermal degradation kinetics of non-biodegradable polymers used mainly in packaging. In this direction, the thermal degradation kinetics of PET/PLA blends was investigated using non-isothermal thermogravimetric data and a simulation model based on the random-scission mechanism. Specifically, we extended the model originally developed by Sánchez-Jiménez, Pérez-Maqueda and Criado based on the original idea of Simha and Wall to simulate the thermal degradation of polymer blends in pyrolytic conditions. A system of differential equations was set and solved based only on the kinetic parameters obtained from the neat polymers and without any additional adjustable parameter. It was found that this model describes fairly well the thermal degradation of several PET/PLA blends in a large conversion range. Deviations were observed at low conversions where degradation of PLA is promoted by ester interchange reactions with PET and at intermediate conversions where possible synergistic effects may take place. Furthermore, the addition of nanoparticles seem to retard the diffusion of the volatile degradation products out of the polymer, so that the onset of mass loss is at higher temperatures for the blend nanocomposites compared to neat blend. This was taken into account in the model by including an additional diffusion-related term to the kinetic constant of the degradation.

To study the stability of hydroxylamine sulfate (HAS) when mixed with metal ions (especially Fe3+), the effect of Fe3+ doping on the thermal decomposition of HAS was studied by differential scanning calorimeter. The results indicate that HAS decomposes at 365–376 K and average thermal effect of P1 and P2 are approximately 632.6 J/g and 66.9 J/g, respectively. Fe3+ increases thermal effect of P1 and P2, but it decreases the initial decomposition temperature (To) of P1, and delays the To of P2. The density functional theory calculations results reveal a detailed 8-step reaction model of HAS decomposition with the formation of NH3OH+ as the key step. Notably, Fe3+ affects the thermal decomposition process of HAS by forming a coordination compound Fe(NH2OH)63+ with NH2OH. In addition, model-free method prediction shows that Fe3+ reduces the kinetic parameters and the thermal hazard parameters.

The purpose of this paper is to examine whether isothermal microcalorimetry can be used to determine the corrosion rates of metals embedded in wood. Metal fasteners were driven into dowels of wood treated with alkaline copper quaternary, a common wood preservative that increases the corrosiveness of wood. The dowels were stored in a nearly 100% relative humidity environment at 27°C for one year; throughout the exposure period, dowels were removed and the thermal power generated by the sample was measured in an isothermal calorimeter. Measurements over the 1-year exposure showed that the thermal power depended upon the wood moisture content and ranged from 0 to 200 µW. The heat, determined by integrating thermal power over time, was higher than expected compared with the total amount of mass lost due to corrosion at the end of the experiment. Despite this, the technique shows promise as a method to determine how changes in wood moisture content affect the corrosion rates of metals in contact with preservative treated wood.

Mathematical deconvolution (MD) can offer a simple way to solve independent multistep kinetics. However, there are always doubts about the cases in which it loses efficiency.This work analyzes the adjustability of the Fraser-Suzuki function (FSF) for processes with F0, D1, and Pn models. Curves dα/dt vs t for were simulated and fitted using the FSF for each case. Their kinetic parameters were determined and compared with the real ones. Furthermore, an example of deconvolution was analyzed. The results show that the FSF fit does not lead to satisfactory results when applied to dα/dt vs t curves that show sharp peaks and sudden decays.This work is not intended to discourage MD use since it has led to correct parameters in many investigations. However, the aim is to show examples of limitations so that the analyst can choose other appropriate approaches. Therefore, MD should always be used with caution and judgment.

The mechanism underlying the isothermal decomposition of DNTF in various amino nitrogen-rich compounds was explored in this work. Results showed interactions between DNTF and the hybrid systems of nitrogen-rich molecules containing NH bonds, and these interactions accelerated the decomposition of DNTF. The kinetic parameters of the samples at the pre-decomposition stage were calculated under isothermal conditions, and the results confirmed that the activation energy of the hybrid system was significantly lower than that of the DNTF monosystem. According to FT-IR and HPLC measurements, it was found that the decomposition rate of DNTF in hybrid system was faster than that of AMTZ, and that the furoxan ring broke first, followed by the accelerated decomposition of AMTZ, which also indicated that AMTZ could accelerate the decomposition of DNTF, and they may have promoted each other's decomposition.

An interpenetrating metal-ceramic composite (IMCC), consisting of an open-porous alumina preform (26vol%), infiltrated with an AlSi10Mg alloy is investigated for its thermal properties and the microstructural impact on the thermal cycling behavior. Specific heat capacity, thermal conductivity and the coefficient of thermal expansion are investigated experimentally. Next to dilatometry experiments, an in-situ SEM setup with digital image correlation of the natural microstructure of the composite is used as a recognizable pattern on the sample surface to evaluate strain and microstructural changes during heating and cooling. The interpenetrating phase composite is also modelled based on reconstructed and generated microstructures. Extensive numerical studies are conducted with varying boundary conditions, interface properties, initial cooling temperatures, temperature dependent material properties and inclusion of pores. Microstructural investigations show phenomena of plasticity, creep, crack formation and interface detachment which is supported by numerical findings. Microstructural changes during heating and cooling in form of crack formation occur in the metallic phase and metallic precipitation. The influence of the microstructural processes on the thermal expansion behavior are discussed in comparison to existing hypotheses from literature.

This work explores the pyrolysis characteristics and kinetic behavior of paper-laminated phenolic printed circuit boards (PLP-PCBs) using thermogravimetric analysis under non-isothermal linear heating programs. The initial estimation of the kinetic parameters during the pyrolysis was obtained from the analysis of the experimental data by three isoconversional kinetic models, i.e. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) integral methods, as well as the Friedman differential method. For all three methods, the apparent activation energy exhibited a strong dependence on the degree of the reaction conversion. To allow for the complexity of the reactions involved in the PLP-PCB pyrolysis, two distributed activation energy models (DAEMs) with a first-order reaction function were derived by assuming the discrete and multi-Gaussian distributions for the activation energies. A six pseudo-component Gaussian DAEM was able to accurately describe the PLP-PCB pyrolysis. By applying the discrete DAEM algorithm, the pyrolysis of PLP-PCB could be precisely characterized by 37 dominating reactions.

The efflorescence of sodium carbonate decahydrate (SC-DH), characterized by the solid-state thermal dehydration to form its monohydrate (SC-MH), occurs below its melting point positioned slightly above room temperature and at a lower atmospheric water vapor pressure (p(H2O)). Applying a thermogravimetry (TG) that covers temperatures lower than room temperature enabled us to systematically trace the efflorescence of SC-DH under various heating programs in a dry N2 stream, using which the kinetics of the efflorescence was formally described by the basic kinetic equation. Meanwhile, when the sample temperature reached the melting point of SC-DH midway through the efflorescence process, the thermal dehydration switched from solid-state mode to liquid-state one and exhibited a complex multistep mass loss behavior to form SC-MH. The multistep mass loss behavior and its changes with the reaction conditions were overviewed using a humidity-controlled TG at various atmospheric p(H2O).

Olive Pomace (OP) biomass has a high potential for biofuel production. Dry torrefaction of OP was carried out at 200–290 °C in an inert environment in a tubular reactor. Low-Density Polyethylene (LDPE) is the most common plastic seen in landfills. Therefore, the blends of Olive Pomace with LDPE were torrefied at different ratios. The product yield and characteristics of torrefied OP were studied. As the temperature increased, the torrefied OP's mass yield decreased while the HHV increased. In the case of OP-LDPE blends, mass yield and HHV increased with the increase in LDPE content. Results showed that mass yield ranged between 59.2–82.6% for torrefied olive pomace depending on torrefaction temperature. 12% increase in mass yield was noticed when 30 wt% LDPE was blended with OP as compared to the OP at 240 °C. As for fuel properties, torrefaction enhanced HHV from 19.8 to 24.2 and 25.5 MJ/kg for OP at 290 °C and OP-LDPE blend of 30% plastic at 240 °C, respectively. Additionally, the fuel ratio rose to 0.4; the combustibility index reduced to 63.5 MJ/kg for torrefied biomass at 240 °C. The fuel ratio drastically dropped when LDPE was blended with olive pomace, reaching 0.09 with a combustibility index of 284.55 MJ/kg. Thermogravimetric analysis (TGA) revealed that hemicellulose decomposed at the specified temperature range (>200 °C), while cellulose and lignin partially decomposed. TGA showed that plastic breaks down at one stage at temperatures greater than 400 °C. According to Fourier Transform Infrared Spectroscopy (FTIR), adding LDPE replaced alkenyl groups with ketones and aldehydes. FESEM analysis showed that adding plastic clogged biomass pores resulted in higher mass yield.

Heating at the rate of several hundred Kelvin per second in fast scanning calorimetry (FSC) experiments was found to change the route of polymorphic transformation. Upon the increase of the heating rate first the endothermic solid-state polymorphic transition is hindered to give a consecutive melting of low-temperature form and crystallization of high temperature polymorph. At higher heating rates, only melting of low-temperature polymorph is observed much below an equilibrium melting point. This thermal behavior with depression of final melting point by 30 K was observed for tert‑butylthiacalix[4]arene tetrasubstituted with (ethoxycarbonyl)methoxy groups (1), which does not sublimate at heating. A similar shift of the endothermic solid-state polymorphic transition by temperature at fast heating was found for caffeine (2), however the melting of low-temperature polymorph is not observed due to sublimation of the compound at elevated temperatures. The heating rates, at which a significant depression of the melting points of 1 and 2 may be expected in absence of sublimation, were calculated using equations of thermal kinetics derived from the data of conventional differential scanning calorimetry. The results give a practical guide for the preparation of glassy forms of the substances capable of endothermic solid-solid transition below melting point of high-temperature form.

The flow direction of the coolant in cooling channels relative to the reactant gasses is critical for thermal performance. Here, four different flow patterns for the serpentine channel and three different flow patterns for the straight channel are numerically studied based on index of uniform temperature (IUT), maximum temperature, and pressure drop. For the serpentine flow channel, the left-cross pattern has the lowest index of uniform temperature and maximum temperature, while the right-cross pattern has the highest. The parallel and left-cross patterns exhibits best and worst performances, respectively, in terms of cooling performance for the straight channel. Nearly the same pressure drops are obtained for all flow patterns of both channel configurations. When the parallel pattern is used instead of the counter pattern in the straight channel and the left-cross pattern is used instead of the right-cross pattern in the serpentine channel, the IUT improves by 55.45% and 27.39%, respectively.

The maximum hydration heat release Qmax is one of the most concerned kinetic parameters for hydration of cementitious materials. In this study, we specially investigated the effect of the mathematical calculation approach, heat flow monitoring time, and fly ash (FA) content on the obtained Qmax values of FA cement paste. The isothermal hydration heat flows of cement paste with 0%, 20%, 40% and 60% FA contents have been monitored for 250 hours at 20°C. Two conventional Qmax calculation approaches, including Knudsen's equation and the three-parameter exponential function, have been utilized to obtain Qmax values for different cementitious systems. The results indicate that irrespective of the calculation approach or monitoring time, mathematically derived Qmax linearly decreases along with the increase of FA content, which is consistent with the determined enthalpy of the binary cement system. Furthermore, the calculated Qmax increases with the extension of heat flow monitoring time, and different calculation approaches can yield varied Qmax values. However, the discrepancies between the two approaches gradually diminish as the monitoring time extends. It is recommended that for cement paste without FA addition, a minimum heat flow monitoring time of 7 days is necessary to obtain a reliable Qmax value using Knudsen's equation, while for the exponential function, a monitoring time exceeding 7 days is advised. For cement paste with FA addition, neither Knudsen's equation nor three-parameter exponential function can derive a relatively accurate Qmax value for FA within the limited heat flow monitoring duration in this study.

This work reports on the thermal properties of non-isocyanate polyurethanes (NIPUs) obtained via the polyaddition reaction of polyether diamine with five membered tri(cyclic carbonate) by using a prepolymerization method. The non-isocyanate polyurethanes were further chemically modified by trifunctional polyhedral oligomeric silsesquioxane (POSS) - triglycidylisobutyl POSS (3epPOSS), resulting in hybrid composite materials containing 5 to 15 wt% POSS. Thermal properties of the obtained materials were studied by various methods, such as Thermogravimetric analysis (TGA), Pyrolysis with gas chromatography and mass spectrometry (Py-GC/MS), and Microscale Combustion Calorimetry (MCC), and were later discussed in dependence of their composition and structure assessed by Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques. FTIR spectra confirm the successful synthesis of NIPUs and their hybrids with POSS. The results of XRD and SEM revealed homogeneous distribution of silsesquioxane in the bulk of the NIPU matrix. Depending on the POSS concentration in the PU hybrids, various self-assembling structures were formed. TGA analysis indicated a two- and three-step degradation process of NIPU materials in inert and oxidative atmospheres, respectively. Significantly higher degradation temperatures and a remarkably reduced degradation rate for composite materials compared to unmodified NIPU matrix were observed during the second degradation step under an oxidative atmosphere. Based on the overall stabilization effect (OSE), hybrids containing 10 and 15 wt% of 3epPOSS were more thermally stable than the unmodified NIPU matrix. Py-GC/MS demonstrated that the products of NIPU thermal decomposition originate from hydroxyurethane moieties, main substrate core structures, and others, such as catalysts. Incorporation of 3epPOSS into the NIPU matrix decreases its flammability, as evidenced by the results of the MCC, with a nearly 20 % reduction effect noted for the composite with of 15 wt% of POSS, compared to the unmodified NIPU matrix. Importantly, chemical modification of NIPU by POSS caused a reduction of the heat of combustion in the final stage of degradation by ca. 30 %.

The thermolysis of the co-agglomerates (CACs) of the attractive nitramines RDX, BCHMX, HMX and CL-20 with 1,3-diamino-2,4,6-trinitrobenzene (DATB) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) was studied by means of differential thermal analysis (DTA) and differential scanning calorimetry (DSC), using the Kissinger method for output evaluation. The insertion of both DATB and TATB molecules into nitramine crystal lattices markedly increased the thermal sensitivity of the resulting CACs to overheating. Depression in melting points was detected in all CACs and, with the exception of RDX CACs, also in the exothermic peaks. The RDX CACs differ from the other studied CACs by their decomposition in the liquid state. The activation energies (Ea), obtained correlate with asymmetric N-O stretching vibrations, confirming the important influence of ‒N‒O····H‒H= interactions in CACs; a similar correlation with asymmetric NO2 stretching confirms the interactions of DATB and TATB molecules with nitramine molecules through van der Waals forces. The insertion of DATB or TATB into the crystal lattice of HMX or CL20 changes their polymorphic modification from β- to δ- and in the latter case from ɛ- to β- modifications in the corresponding CACs. The correlations of the Ea values with the square of detonation velocity as a representative of performance and with the heat of combustion as a representative of the energy content are consistent with already previously described relationships of this type, including exceptions for pure nitramines.

Thermodynamic parameters, including heat transfer coefficient and specific heat capacity of chemicals, are key information for the application of reaction calorimetry in chemical process safety and optimization. Conventional methods for parameter calibration used in commercial reaction calorimeters exhibit limited efficiency and accuracy. In particular, heat dissipation and calibrated parameters vary with temperature during calibration. The impact of these issues on measurement results has not been carefully considered so far. Therefore, this study presents a power oscillation calibration method, for estimating the heat dissipation coefficient at the reference temperature. By generating temperature oscillation and averaging the results of multiple measurement stages, the parameters can be determined, while the impact of parameter variation with temperature is inhibited. The comparison experiments confirm advantages of the proposed method. Finally, the application of the method in power compensation calorimetry is also demonstrated by experiments.

In present work, the estimation of vapor pressures of 3-formylchromone and 3-formyl-6-methylchromone by the isothermal thermogravimetry method is presented. Briefly, this method consists of measuring the rate of mass loss as a function of temperature in a cylindrical cell and with a flow of nitrogen. To derive the vapor pressure, the Langmuir equation was used, from which the vaporization constant was calculated using anthracene as a calibrating compound. Subsequently, the vapor pressures 3-fromylchromone and 3-formyl-6-methylchromone were estimated. From the vapor pressure, the enthalpy of sublimation was calculated using the Clausius-Clapeyron equation for each compound at its mean sublimation temperature. Finally, the enthalpy of sublimation was calculated at T = 298.15 K. The entropy and Gibbs energy of sublimation at the same temperature were determined. In order to test the validity of the method, the vapor pressures of phenanthrene and pyrene were calculated. The values obtained by isothermal thermogravimetry agree with those reported by other techniques.

High temperature vaporisation thermodynamic studies over D-9 and T-91 stainless steel samples were carried out in the temperature range 1202–1529 K and 1232–1530 K respectively, by using Knudsen Effusion Mass Spectrometry (KEMS). These studies revealed that both the alloys undergo incongruent vaporisation. Cr(g), Mn(g), Fe(g) and Ni(g) were the neutral vapour species observed over the D-9 alloy. Cr(g), Mn(g) and Fe(g) were the neutral vapour species observed over the T-91alloy. Partial pressure-Temperature relations were derived using KEMS for the first time. Apparent enthalpies of vaporisation data were deduced by second law method. Chemical activities of all the major metallic elements (Fe, Cr, Ni and Mn) in the commercial grade D-9 austenitic stainless steel were determined in the temperature range of 1202–1529 K. In case of T-91 ferritic steel, chemical activities of Fe, Cr and Mn were determined in the temperature range of 1232 -1530 K.