Pressure Differential Scanning Calorimeter Research Articles

Thermodynamic phase equilibria study of Hythane (methane + hydrogen) gas hydrates for enhanced energy storage applications

Hydrogen blending with natural gas has become an effective technique for incorporating the characteristics of natural gas and facilitating the storage and transportation of hydrogen gas. The transportation of hydrogen and natural gas (methane) blend, also referred to as Hythane, presents numerous challenges, advantages, and disadvantages that differ based on the technology employed. The current research showcased a thorough examination of the thermodynamics involved in studying the three phase equilibrium analysis of gas hydrate technology for storing Hythane gas mixtures. Three different Hythane compositions varying in hydrogen percentage were selected, and the isochoric gas hydrate phase equilibria study was performed. The experimental results of phase equilibria and thermodynamic modelling using CPA EOS in software were compared. A similar study was also conducted in the presence of a 5.56 mol % THF solution to understand the reduction in the pressure requirement for the phase equilibria. Results from the mixed Hythane+THF gas hydrate findings suggested stable gas hydrate formation at much lower pressure requirements, increasing the credibility of storing Hythane mixtures in gas hydrates at moderate conditions. The gas compositions for each experiment were analyzed using gas chromatography to evaluate the presence of the desired gas in the hydrate phase. Heat exchange during the gas hydrate dissociation was analyzed using a high pressure differential scanning calorimeter (DSC). The change in the heat release temperature also indicates the stability of the gas hydrate, and with increasing hydrogen gas in the blend, the gas hydrate stability decreased. The Clausius-Clapeyron equation was employed to compute the heat of gas hydrate dissociation, and a comparison was made with the heat of dissociation obtained from the DSC study. The experimental investigations on Hythane gas hydrates were performed to find the hydrogen storage inside the gas hydrate phase and compare it with the previous studies of pure hydrogen hydrates. To demonstrate the Hythane gas transportation, Hythane gas hydrate pellets were formed, followed by their storage in a controlled environment to observeany changes in pressure and temperature. The Hythane gas hydrate pellets demonstrated exceptional stability of Hythane gas presenting an intriguing prospect for utilizing gas hydrate technology in Hythane gas transportation.

Thermal stability of levopimaric acid and its oxidation products

Biofuels are renewable alternatives to fossil fuels. Levopimaric acid‒base biofuels have attracted increasing attention. However, their stability remains a critical issue in practice. Thus, there is a strong impetus to evaluate the thermal stability of levopimaric acid. Through thermogravimetry (TG) and a custom-designed mini closed pressure vessel test (MCPVT) operating under isothermal and stepped temperature conditions, we investigated thermal oxidation characteristics of levopimaric acid under oxygen atmosphere. Thin-layer chromatography (TLC) and iodimetry were used to measure the hydrogen peroxides generated by levopimaric acid oxidation. A high pressure differential scanning calorimeter (HPDSC) was used to assess hydroperoxide thermal decomposition characteristics. Gas chromatography-mass spectrometry (GC-MS) was used to characterize the oxidation products. The thermal decomposition kinetics of levopimaric acid were thus elucidated, and a high peroxide value was detected in the levopimaric acid. The decomposition heat (QDSC) and exothermic onset temperature (Tonset) of hydroperoxides were 338.75 J g−1 and 375.37 K, respectively. Finally, levopimaric acid underwent a second-stage oxidation process at its melt point (423.15 K), resulting in complex oxidation products. Thermal oxidation of levopimaric acid could yield potential thermal hazards, indicating that antioxidants must be added during levopimaric acid application to protect against such hazardous effects.

The Quality and Composition of Fatty Acids in Adipose Tissue-Derived from Wild Animals; A Pilot Study

The aim of this work was to study the quality (oxidative stability), fatty acids (FAs) profile and their distribution in triacylglycerol (TAG) molecules of hunted game wild fat (HGWF) obtained from wild boar, badger, and wild goose. Health lipid indices were calculated. The determination of FAs composition was carried out by gas chromatographic analysis of fatty acid methyl esters (FAME). Enzymatic hydrolysis and thin layer chromatography were used to determine the positional distribution of FAs in the internal and external positions of triacylglycerols (the regiospecific structure of triacylglycerols) of the obtained HGWF. A pressure differential scanning calorimeter (PDSC) was used to determine the oxidative stability of tested HGWF. The lipid fraction isolated from subcutaneous adipose tissues was dominated by MUFA, on average 46–50% of total FAs, and by SFA, on average 32–36% of total FAs. Palmitic acid was located mainly in the internal position of TAGs of the analyzed HGWF, whereas external positions were occupied by unsaturated oleic acid. Such a structure is responsible for normal fat absorption from food and it prevents the formation of insoluble calcium salts. Considering FAs profile, quality and the oxidation stability among all tested fat samples, the boar fat seems to be the most favorable.

Rapid screening method for hydrate agglomeration and plugging assessment using high pressure differential scanning calorimetry

Gas hydrate formation during subsea oil and gas production can result in flowline blockages, which present enormous economic and safety risks. Certain crude oils have natural anti-agglomerant (AA) properties, which facilitate their non-plugging behavior over a defined operating window. Thus, it is crucial to be able to easily screen a crude oil system for its tendency to form hydrate plugs. In this paper, we present a Hydrate Plugging Assessment (HPA) technique that can be used as a rapid screening method to evaluate the plugging tendency using a high pressure differential scanning calorimeter (HP-DSC). The technique requires a small crude oil sample (~15 mg), and the experimental time is relatively short. In this work, HP-DSC tests were conducted on 13 crude oils (22 to 45 ˚API). Tests were conducted at various water contents, salinity, chemical dosage (without/with AAs), and different hydrate structures. The results show that an increase in water content destabilizes the emulsion, and increases the hydrate plugging risks. An increase in salinity decreases hydrate plugging tendency. Different hydrate crystal structures showed that for a similar water content, salinity, and driving force, structure II (sII) hydrates have a slightly greater agglomeration tendency compared to structure I (sI) hydrates. Finally, the effect of combining a low stability oil with a high stability oil showed that the resulting emulsion retained the high stability property, paving the possibility for natural oil treatment. In summary, these studies show that the HPA technique is a cost-effective and attractive method to evaluate hydrate plugging tendency.

Kinetics and thermodynamics of near eutectic Mg-Mg2Ni composites produced by casting process

This article reports the hydrogenation properties of several Mg–Mg2Ni composite specimens with increasing Ni content: 4.4, 11.3 (eutectic), and 16.3 (in at%). Mg–Mg2Ni composites were prepared by means of induction melting, followed by simple mechanical chipping of the casts. The hydrogenation and dehydrogenation reaction kinetics were studied, and reaction mechanisms were described by means of solid-gas reaction modeling. Absorption and desorption properties were evidenced to be diffusion controlled, with hydrogen diffusion through hydrided/dehydrided phases being the rate limiting step in most cases (the migration of metal/hydride interface at a constant velocity being rate-limiting in only few of them). The kinetics study was supported by a thorough thermal analysis to provide in-depth insights of the decomposition reaction. Hence, thermogravimetry (TG) and pressurized differential scanning calorimeter (PDSC) were combined to investigate the dehydrogenation properties such as hydrogen gravimetric density, reaction onset temperature, enthalpy and activation energy as a function of Ni content. Structural analysis included X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM) to discuss the structural stability and microstructural evolution as a function of cycles, notably during the activation procedure. Finally, cyclic performance was evaluated for 100 cycles, using a custom-made large-scale reactor to demonstrate scale-up feasibility.

Experimental investigation of the chemical degradation of lubricating grease from an energy point of view

Abstract The chemical degradation/oxidation of lubricating grease is investigated experimentally from an energy point of view. A Pressure Differential Scanning Calorimeter (PDSC) is used to measure the activation energies of two lithium-complex greases and to monitor their chemical degradation through induction time. For this purpose, an experimental setup consisting of a heating chamber, a temperature controller and an energy meter is designed, built, and calibrated to heat up grease samples and measure pure energy absorption during the chemical degradation at different test temperatures. A relationship between the energy absorption of the grease and its chemical degradation is established that is independent of the testing time and temperature. It is shown that the energy absorption of the grease approaches to an identical maximum value in a shorter time in high temperatures and a longer time in low temperatures. The maximum energy absorption depends on the grease type and experimental results reveal that it can be used to estimate the grease chemical life. A roller tester rig is used to measure and compare the lubrication ability of two chemically degraded grease samples and to validate the results of the research. To gain further insight, experimental results are presented to examine the flow characteristics of a chemically degraded grease in an elastohydrodynamic (EHL) line contact with a comparison to that of the fresh grease.

The Oxidation Stability and Magnetorheological Properties of MR Grease Based on Different Kinds of Base Oil

Abstract Magnetorheological (MR) grease based on mineral oil, silicon oil, and polyalphaolefi was prepared directly by synchronizing with synthetic grease, respectively. The oxidation stability of each was measured using a pressurized differential scanning calorimeter, whereas sedimentation stability was evaluated by the natural settling process. The effects of base oil and magnetic field strength on MR response of the suspensions were investigated via measurement of the rheological properties, including storage modulus, loss modulus, and MR effect under dynamic oscillation test. It was confirmed that ethyl silicon oil–based MR grease has excellent oxidation stability, good sedimentation stability, and outstanding MR effect. In addition, the MR grease exhibited characteristics of a solid state both with and without magnetic field.

Experimental studies on hydrogen hydrate with tetrahydrofuran by differential scanning calorimeter and in-situ Raman

Clathrate hydrate is a kind of environment-friendly material for storing hydrogen under a certain condition of temperature and pressure. In this work, tetrahydrofuran aqueous solution with concentration of 3.0 mol% was adopted to investigate hydrogen storage process. Moreover, thermal property of hydrate was measured by high pressure differential scanning calorimeter, and mechanism of hydrate-based hydrogen storage was studied by in-situ Raman. Especially, gas uptake, morphology and structures change of compounds from gas/liquid interface towards hydrate layer were monitored in the process of hydrate formation. Thermal experiments illustrate that thermal data for tetrahydrofuran-hydrogen binary hydrate under extra high pressures could be effectively obtained by high pressure differential scanning calorimeter, moreover, memory effect shows no influence on thermal state of hydrate but weakly affects water aggregation. Kinetics and microscopic experiments illustrate that a special pressure drop and some tetrahydrofuran hydrates with unstable structure can be found under conditions of 273.15 K and 14.53 MPa. The pressure drop involves into hydrogen molecules tunneling movement among hydrate cavities. Moreover, hydrogen molecules show a positive effect on binary hydrate stability. Further, the density of 1.875 g/Lwater shows that hydrogen storage process via clathrate hydrate is an excellent method to store hydrogen.

Thermal characterization of crude oils by pressurized differential scanning calorimeter (PDSC)

Abstract In this research, pressurized differential scanning calorimeter (PDSC) were used to estimate the thermal and kinetic behaviour of two different crude oils from Tatarstan oil fields under three different pressures (100, 600, 2000 kPa) at a constant heating rate (10 °C/min). The heat flow curves of both crude oils indicated two reaction regions known as low temperature oxidation (LTO) and high temperature oxidation (HTO). The reaction intervals were shifted to lower temperature regions with the increase in pressure. The activation energies were calculated according to Borchardt & Daniels and Roger & Morris methods and it was observed that the activation energies were decreasing at elevated pressures.

Ranking of kinetic hydrate inhibitors using a high pressure differential scanning calorimeter

A High Pressure Differential Scanning Calorimeter (HP-µDSC) was used to characterize the kinetic inhibition performance of several kinetic hydrate inhibitors (KHIs) up to 390 bar (39 MPa) of model natural gas. A novel protocol was devised to increase the spread between effective KHIs to obtain their performance ranking. The natural gas used in the study was a mixture of 90 mol% methane and 10 mol% propane. Linear cooling ramps at a constant cooling rate of 0.5 K/min were used under isobaric conditions. Both the formation temperature of natural gas hydrate during a linear cooling ramp and the amount of hydrate formed were used for comprehensive analysis. The second method was based on the growth inhibition of natural gas hydrates and opened a new possibility that only several repeat measurements may be sufficient for fast screening of good KHIs. The results showed that HP-µDSC is a promising tool for the evaluation of kinetic inhibition performance of KHIs that can only be obtained in minute quantities.

Experimental and modelling studies on thermodynamic methane hydrate inhibition in the presence of ionic liquids

This paper presents a series of experimental and modelling studies on the thermodynamic inhibition effects of four ionic liquids on the methane hydrate formation. The investigated ionic liquids are 1-methyl-3-octylimidazolium chloride [MOIM-Cl], 1-methylimidazolium hydrogen sulfate [H-MIM-HSO4], tetraethylammonium iodide [TEA-I], and 1-hexyl-3-methylimidazolium iodide [HMIM-I]. The impact of 0.1 mass fraction concentration ionic liquids on the methane hydrate phase boundary was evaluated by measuring the dissociation temperature of methane hydrate in the pressure range of 5.1–11.1MPa, using a high pressure differential scanning calorimeter. The molar dissociation enthalpy of methane hydrates was calculated using the Clausius–Clapeyron equation. The density was measured for 0.10 mass fraction of aqueous solutions of ionic liquids at 293.15K, and then compared to the commercially available gas hydrate inhibitors. The results demonstrated that 1-methylimidazolium hydrogen sulfate [H-MIM-HSO4] has the highest inhibitory performance among the four ionic liquids considered. Moreover, the Dickens and Quinby-Hunt (electrolyte) model was applied to predict the phase equilibrium data of the studied ILs. The predicted data is in agreement with the experimental data.

Tetra-n-heptyl ammonium tetrafluoroborate: Synthesis, phase equilibrium with CO2 and pressure swing absorption for carbon capture

Based on the analyses of the interaction energy with CO2, COSMO calculation and melting temperature, a quaternary ammonium salt, tetra-n-heptyl ammonium tetrafluoroborate ([thepAm][BF4]), was synthesized using [thepAm][Br] and NaBF4 as the raw materials. The as-synthesized [thepAm][BF4] was characterized by FTIR and NMR. The solid–liquid–gas (SLG) phase equilibrium line of the [thepAm][BF4]–CO2 system was determined by high pressure differential scanning calorimeter, indicating it was more stable than [thepAm][Br] because of higher melting temperatures of [thepAm][BF4] in pressurized CO2. The solubility data of CO2 in [thepAm][BF4] at 313.2, 323.2 and 333.2K up to 15MPa were measured by using the high-pressure quartz spring approach. The Peng-Robinson equation of state with the van der Waals-1 mixing rules was employed to calculate the solubility and SLG phase equilibrium data. Results showed high molar fractions of CO2 in [thepAm][BF4] at high pressures (e.g., molar fraction of 0.88 at 10.0MPa and 313.2K). A cyclic absorption–desorption procedure and a pressure swing absorption process were proposed and tested for CO2 capture/separation from the H2, CO and CO2 mixture by using [thepAm][BF4] as the absorbent, verifying its selective capture of CO2 over H2 and CO. The study may open a new way for CO2 capture.

Near Critical Carbon Dioxide Sorption Induced Crystallization in PET

Near critical carbon dioxide sorption equilibria at 50°C and pressures up to 40 atms are analyzed and interpreted on the basis of the multiple sorption mechanisms possible in a glassy amorphous and semi crystalline polymer. Varying the penetrant-polymer testing temperature and external pressure it is possible to meet the full range of possible sorption behavior, from ideal Fickian diffusion to limiting relaxation controlled kinetics. Low sorption levels of low-pressure gases are attained through an ordinary Fickian mechanism. At higher gas pressures, however, higher penetrant sorption levels induce polymer relaxation affecting the final sorption behavior. A highly interacting solvent, as Carbon Dioxide in near critical conditions, leads to anomalous sorption ranging from relaxation controlled Fickian diffusion to limiting Case II and diffusion controlled relaxation, at high solvent uptakes (sorption from high activity vapor or from liquid phases). Generally, swelling has been observed to be accompanied by a solvent induced crystallization as detected by means of High pressure Differential Scanning Calorimeter (DSC) and Wide Angle Xray Scattering (WAXS).

Chain length effect of ionic liquid 1-alkyl-3-methylimidazolium chloride on the phase equilibrium of methane hydrate

A high pressure differential scanning calorimeter was used to determine the dissociation temperature of methane hydrate in the presence of ionic liquid 1-alkyl-3-methylimidazolium chloride under a constant pressure ranging from 5 to 35 MPa. A homologous series of 1-alkyl-3-methylimidazolium chloride with different alkyl chain lengths: 1-ethyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride and 1-decyl-3-methylimidazolium chloride, were chosen to examine the chain length effect on the dissociation temperature for methane hydrates. All these ionic liquids have inhibition effect on methane hydrate formation. Moreover, the shorter the alkyl chain length is, the stronger the inhibition effect is. That is, the inhibition effect of these ionic liquids on the methane hydrate formation is in the order of 1-ethyl-3-methylimidazolium chloride>1-hexyl-3-methylimidazolium chloride>1-decyl-3-methylimidazolium chloride. The three-phase vapor–liquid–hydrate equilibrium condition of methane hydrate in the presence of 1-alkyl-3-methylimidazolium chloride was successfully described by a predictive thermodynamic model. The Peng–Robinson–Stryjek–Vera equation of state incorporated with COSMO-SAC activity coefficient model and the first order modified Huron–Vidal mixing rule were applied to evaluate the fugacity of vapor and liquid phase. An explicit pressure dependence of the Langmuir adsorption constant in the modified van der Waals and Platteeuw model was applied to determine the fugacity of hydrate phase. The average absolute relative deviation in predicted dissociation temperature from the predictive thermodynamic model was 0.54%. In addition, these experimental data of dissociation temperatures were further correlated to a general correlation of Østergaard et al. (J. Petroleum Sci. Eng. 48 (2005) 70–80) and the average absolute relative deviation in the correlated dissociation temperature was 0.05%.

Air Injection for Enhanced Oil Recovery: In Situ Monitoring the Low-Temperature Oxidation of Oil through Thermogravimetry/Differential Scanning Calorimetry and Pressure Differential Scanning Calorimetry

Low-temperature oxidation (LTO) of oil plays an important role in air-injection based oil recovery processes. Systematic investigations on the regularities of LTO reactions, especially those decoupled with the influences of mass transfer, were highly expected to improve field application and even to develop new strategies for heavy oil recovery. In this contribution, both thermogravimetry/differential scanning calorimeter and pressure differential scanning calorimeter were employed as microreactors to in situ monitoring the heat release and mass loss performances of the LTO process under different oxygen partial pressures. The total amount of heat resulted from LTO reactions of oil was observed in a linear relationship with oxygen partial pressure. A one-step reaction model was proposed to simulate the low-temperature mass loss behavior. The kinetic parameters were calculated based on the Arrhenius expression and the assumption of distributed activation energy. These results indicated the feasibility of in situ generated heat during low-temperature oxidation by the promotion of oxygen partial pressure and the contact between oil and oxygen with little loss of deposited oil.

토크 측정과 시차주사열량계를 이용한 수용성 고분자 화합물의 하이드레이트 저해 성능 평가

본 연구에서는 토크 측정과 고압 시차주사 열량계를 이용하여 pyrrolidone, caprolactam, acrylamide 계열 수용성 고분자들의 하이드레이트 저해 성능을 평가하였다. 실험 결과, 세 종류의 고분자가 모두 동역학적인 하이드레이트 생성억제제 효과를 나타내는 것으로 확인되었으며, 특히 0.5 wt% polyvinylcaprolactam (PVCap)의 경우 34.4분의 하이드레이트 유도 시간, 15.9 K의 subcooling 성능을 보이며 12.3 분, 6.0 K의 순수 물 시스템보다 월등한 저해 성능을 나타내었다. 0.5 wt% polyvinylpyrrolidone (PVP)의 경우 중간 정도의 저해 성능을 보였으며, polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA)의 경우 각각 0.5 wt%와 5.0 wt%의 농도에서 미미한 하이드레이트 저해 성능을 보였다. 반면에 생성된 하이드레이트 입자의 성장속도와 생성 양에서는 PAM-co-AA가 PVCap과 더불어 가장 월등한 저해 효과를 나타내었다. 또 다른 주요 성능 평가 요소 중 하나인 토크 변화의 경우에는 PVCap이 평균 토크 6.4 N cm로 가장 좋은 성능을 보였으며, 0.5 wt%의 PAM-co-AA 시스템이 평균 7.2 N cm의 값으로 그 뒤를 이었다. 고압 시차주사 열량계를 이용한 수용성 고분자 물질의 저해 성능 평가 실험의 결과는 autoclave 실험의 결과와 유사하였다. PVCap을 첨가한 경우 하이드레이트가 생성되기까지의 유도시간이 가장 길어서 저해성능이 뛰어난 것을 확인하였다. In this work, hydrate inhibition performance of water-soluble polymers including pyrrolidone, caprolactam, acrylamide types were evaluated using torque measurement and high pressure differential scanning calorimeter (HP <TEX>${\mu}$</TEX>-DSC). The obtained experimental results suggest that the studied polymers represent the kinetic hydrate inhibition (KHI) performance. 0.5 wt% polyvinylcaprolactam (PVCap) solution shows the hydrate onset time of 34.4 min and subcooling temperature of 15.9 K, which is better KHI performance than that of pure water - hydrate onset time of 12.3 min and subcooling temperature of 6.0 K. 0.5 wt% polyvinylpyrrolidone (PVP) solution shows the hydrate onset time of 27.6 min and the subcooling temperature of 13.2 K while polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA) solution shows less KHI performance than PVP solution at both 0.5 and 5.0 wt%. However, PAM-co-AA solution shows slow growth rate and low hydrate amount than PVCap. In addition to hydrate onset and growth condition, torque change with time was investigated as one of KHI evaluation methods. 0.5 wt% PVCap solution shows the lowest average torque of 6.4 N cm and 0.5 wt% PAM-co-AA solution shows the average torque of 7.2 N cm. For 0.5 wt% PVP solution, it increases 11.5 N cm and 5.0 wt% PAM-co-AA solution shows the maximum average torque of 13.4 N cm, which is similar to the average torque of pure water, 15.2 N cm. Judging from the experimental results obtained by both an autoclave and a HP <TEX>${\mu}$</TEX>-DSC, the PVCap solution shows the best performance among the KHIs in terms of delaying hydrate nucleation. From these results, it can be concluded that the torque change with time is useful to identify the flow ability of tested solution, and the further research on the inhibition of hydrate formation can be approached in various aspects using a HP <TEX>${\mu}$</TEX>-DSC.

Vapor pressure data of nicotine, anabasine and cotinine using differential scanning calorimetry

The aim of the present study was to determine the vapor pressures of three tobacco alkaloids using the high pressure differential scanning calorimeter based technique, in accordance with a standard test method ASTM E 1782. The measurements were conducted in the pressure range from 15 to 1000kPa. Temperature ranges for (l)-nicotine were from 447.7 to 617.8K, for (±)-anabasine from 478 to 644.3K and for (−)-cotinine from 537.7 to 669.7K. Hermetic-type sealable pans with a pierced lid (pinhole diameter 50μm) and a heating rate of 5K/min were used. The experimental vapor pressure data were fitted to the Antoine equation. Enthalpies of vaporization and the normal boiling temperatures of the compounds were estimated from the measured data. Comparisons are made with published literature data. In addition, a review of the vapor pressure studies of nicotine and anabasine is given.

Measurement and modelling of binary (solid + liquid + vapour) equilibria involving lipids and CO2

The development of solid lipid nanoparticles (SLN) using supercritical fluid at room temperature is an innovative alternative compared to traditional pharmaceutical methods and the safety and drug efficacy of SLN made using supercritical CO2 is increased. One of the micronization techniques which have provided the best results in the production of SLN is particles from gas-saturated solution (PGSS). The solid–liquid–vapour coexistence curve of a solid in a compressed gas is of primary importance in assessing the feasibility of PGSS and the selection of appropriate operating conditions. The objectives of this work are to perform experimental measurements using a high pressure differential scanning calorimeter (DSC) to obtain melting properties as a function of composition and develop a simplified approach to model multiphase equilibria of lipids in compressed CO2. The selected lipid was tristearin. Before assessment of triestearin and CO2 phase equilibrium, the performance of this thermodynamic model was evaluated in two other lipids which provided results with high accuracy.

Mixture of safflower oil and synthetic ester as a base stock for biodegradable lubricants

Biodegradable industrial lubricant applications are gaining popularity with growing environmental concern and stringent government regulations. Plant oils are major base stocks for eco-friendly green lubricants. However, because of their poor oxidation stability, their applications are restricted to limited usages. Improvements of these plant oils can be made either by addition of functional additives or by chemical/genetic modifications. This paper evaluates the synergistic approach of phenolic and aminic antioxidants in safflower oil. Further, to enhance the oxidation properties of the plant oil, we incorporated and studied synthetic esters (SEs) for thermo-oxidative stability by using rotating pressure vessel oxidation test and differential scanning calorimeter. The combination of phenolic and aminic antioxidants at a 2 : 1 ratio exhibited the best synergistic effect, when incorporated into a combination of plant oil and SE. In addition to thermo-oxidative properties, the tribological properties of neat base stocks were also studied. A substitute of mineral oil-based lubricants can be formulated cost effectively by using an appropriate mixture of plant oil and SE. Copyright © 2013 John Wiley & Sons, Ltd.

The Characterization of a Tar Sand Sample Using Differential Scanning Calorimeters

In this study, non-isothermal kinetics and a thermal analysis tar sand sample is studied by differential scanning calorimeter and pressurized differential scanning calorimeter. Differential scanning calorimeter and pressurized differential scanning calorimeter curves revealed two reaction regions in the temperature range of 20–600°C. Effect of pressure was also studied in order to see the thermal behavior of a tar sand sample under different elevated pressures. Two different kinetic methods (ASTM and Borchald and Daniels) were used to determine the kinetic parameters of the samples.