Differential Scanning Calorimetry Methods Research Articles

Assessment of DPPC Liposome Disruption by Embedded Tocopheryl Malonate

In this study, the effect of α-tocopheryl malonate (TM) on physical and structural properties of DPPC liposomes was investigated using ANS fluorescence, DPH, and TMA–DPH anisotropy fluorescence and differential scanning calorimetry (DSC) methods. The presence of embedded TM in DPPC liposomes caused alteration in its phase transition temperatures, structural order, dynamics, and hydration of head groups increasingly with growing TM concentration. The ANS fluorescence results demonstrated that increasing TM presence in the DPPC gel phase due to interrupted membrane structure caused the formation of new binding sites. Temperature investigations in the range of 20 °C to 60 °C showed that increasing temperature rises ANS fluorescence which reaches local and global maxima at 36 °C and 42 °C, respectively. The rising TM concentration at the phase transition temperature of DPPC led to the lowering of ANS fluorescence, indicating a decreased binding of ANS. Simultaneously, during heating, a roughly 10-nm shift of ANS emission maximum was observed. The results indicated that in the fluid phase, the observed quenching appears as a result of increasing accessibility of water molecules into ANS in this region. The DPH results indicated that in the gel phase presence of TM introduced disorder in the hydrophobic acyl chain region led to its fluidization. The TMA–DPH results indicated an increasing disorder in the interface region and an increasing hydration of head group atoms at the surface of the membrane. The increasing concentration of TM results in the formation of multicomponent DSC traces, suggesting the formation of another structural phase. The applied methods proved that the incorporation of TM into DPPC membrane results in the interaction of malonate moiety with DPPC head group atoms in the interphase layer and induces the interruption in the membrane packing order, leading to its structural changes. The presented results show that TM presence could regulate the membrane properties, thus it may indicate one of the possible mechanisms responsible for the effective disruption of cell membranes by TM. The knowledge of molecular mechanism how TM interacts with the membrane will help to elucidate its possible pharmacological activity.

Thermal Behavior Changes of As-Received and Retrieved Bio-Active® (BA) and TriTanium® (TR) Multiforce Nickel-Titanium Orthodontic Archwires.

Multiforce nickel-titanium (NiTi) orthodontic archwires release progressively increasing forces in a front-to-back direction along their length. The properties of NiTi orthodontic archwires depend on the correlation and characteristics of their microstructural phases (austenite, martensite and the intermediate R-phase). From a clinical and manufacturing point of view, the determination of the austenite finish (Af) temperature is of the greatest importance, as in the austenitic phase, the alloy is most stable and exhibits the final workable form. The main purpose of using multiforce orthodontic archwires is to decrease the intensity of the applied forces to the teeth with a small root surface area, such as the lower central incisors, and also provide forces high enough to move the molars. With the optimally dosed forces of multiforce orthodontic archwires in the frontal, premolar and molar segments, the feeling of pain can be reduced. This will contribute to the greater cooperation of the patient, which is of utmost importance to achieve optimal results. The aim of this research was to determine the Af temperature at each segment of as-received and retrieved Bio-Active® and TriTanium® archwires with dimensions of 0.016 × 0.022 inches, investigated by the differential scanning calorimetry (DSC) method. A classical Kruskal-Wallis one-way ANOVA test and multi-variance comparison based on the ANOVA test statistic using the Bonferroni corrected Mann-Whitney test for multiple comparisons were used. The incisor, premolar and molar segments have different Af temperatures, and they decrease from the anterior to posterior so that the posterior segment has the lowest Af. Bio-Active® and TriTanium® with dimensions of 0.016 × 0.022 inches can be used as first leveling archwires by additional cooling and are not recommended for use on patients with mouth breathing.

Thermal Conductivity and Phase-Change Properties of Boron Nitride-Lead Oxide Nanoparticle-Doped Polymer Nanocomposites.

Thermally conductive phase-change materials (PCMs) were produced using the crosslinked Poly (Styrene-block-Ethylene Glycol Di Methyl Methacrylate) (PS-PEG DM) copolymer by employing boron nitride (BN)/lead oxide (PbO) nanoparticles. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) methods were used to research the phase transition temperatures, the phase-change enthalpies (melting enthalpy (ΔHm), and crystallization enthalpies (ΔHc)). The thermal conductivities (λ) of the PS-PEG/BN/PbO PCM nanocomposites were investigated. The λ value of PS-PEG/BN/PbO PCM nanocomposite containing BN 13 wt%, PbO 60.90 wt%, and PS-PEG 26.10 wt% was determined to be 18.874 W/(mK). The crystallization fraction (Fc) values of PS-PEG (1000), PS-PEG (1500), and PS-PEG (10,000) copolymers were 0.032, 0.034, and 0.063, respectively. XRD results of the PCM nanocomposites showed that the sharp diffraction peaks at 17.00 and 25.28 °C of the PS-PEG copolymer belonged to the PEG part. Since the PS-PEG/PbO and the PS-PEG/PbO/BN nanocomposites show remarkable thermal conductivity performance, they can be used as conductive polymer nanocomposites for effective heat dissipation in heat exchangers, power electronics, electric motors, generators, communication, and lighting equipment. At the same time, according to our results, PCM nanocomposites can be considered as heat storage materials in energy storage systems.

DSC Analysis of the Effect of Cold Deformation on the Precipitation Kinetics of a Binary Cu-Sc Alloy.

The present study aimed to investigate the effect of cold deformation on the precipitation kinetics of a binary CuSc alloy containing 0.4 wt.% scandium using the experimental analysis method of differential scanning calorimetry (DSC). Non-deformed and 75% cross-section-reduced cold-rolled supersaturated specimens were tested in non-isothermal DSC runs at up to five different heating rates. The DSC results showed that cold rolling significantly accelerated the precipitation process in the binary alloy, leading to a decrease in the initial and peak temperatures of the exothermic reactions. The activation energies calculated with the Kissinger method indicated that the precipitation activation energy decreased with increasing cold deformation. The findings of this study provide worthy implications to further optimize the processing of Cu-Sc alloys with improved mechanical properties.

Microplastics identification inwaterby TGA-DSC Method: Maharloo Lake, Iran.

Nowadays, one of the biggest challenges is the lack of coordination between the microplastic identification methods used by researchers. To advance our global understanding of microplastic contamination and address the knowledge gaps, we require acceptable or similar identification methods or instruments designed to support the quantitative characterization of the microplastics data. In the current study, we focused on the thermogravimetricanalysis (TGA) with differential scanning calorimetry (DSC) method which is usually used experimentally by other researchers, while we tried to look at this method in a real aquatic environment, Maharloo Lake and its Rivers. A number of 22 sites were chosen for sampling microplastics from water. The mean and median of total organic matter percentage for rivers samples (mean = 88%;median = 88%) was similar to the Maharloo lake (mean = 88.33%; median = 89%), suggesting the existence of a robust potential sink. The differentiation of the organic matter part into labile (e.g., carbon aliphatic and polysaccharides), recalcitrant (e.g., aromatic compounds and most plastics), and refractory fractions was implemented and the results indicated that labile organic matter was dominant in both the lake and the rivers, while recalcitrant and refractory fractions were lower. The river's average labile and refractory fractions were similar to the lake. Although the overall results of the study show combining TGA techniques with other analyticalprocedures can improvethetechnical quality of polymers, interpreting the complex information of those measurements requires a high level ofexpertiseand the technology is still maturing.

Catalytic Properties of Two Complexes of chromium(III) and cobalt(II) with Nitrilotriacetate, Dipicolinate, and 4-Acetylpyridine.

In this paper, a synthesis of two innovative coordination compounds, based on chromium(III) and cobalt(II) ions with N,O-donor ligands (nitrilotriacetate, dipicolinate) and 4-acetylpyridine, is reported. The obtained metal-organic compounds were structurally characterized using the single-crystal X-ray diffraction (XRD) method. The well-defined chromium(III) and cobalt(II) complexes were used as precatalysts in the oligomerization reaction of 2-chloro-2-propen-1-ol and 2-propen-1-ol with methylaluminoxane (MMAO) as an activator. The products of the oligomerization reaction were subjected to full physicochemical characteristics, i.e., time-of-flight mass spectrometry (MALDI-TOF-MS), TGA, and differential scanning calorimetry (DSC) methods. The catalytic activity of the precatalysts in both reactions was calculated and compared with other catalysts known in the literature.

Glass transition and crystallization kinetics of lithium modified zinc borate semiconducting glasses by non-isothermal method

Glass transition and crystallization kinetics of lithium-modified zinc borate glasses of the system 20ZnO.xLi2O.(80-x) B2O3 (x = 10, 20, 30 and 40) have been studied using the non-isothermal method of differential scanning calorimetry (DSC). The 20ZnO·10Li2O.70 B2O3 glass composition has the highest thermal stability and the glass-forming tendency among all other glasses. The activation energy associated with crystallization ((210–318) kJ/mol)), glass transition ((464–531) kJ/mol)), Avrami exponent (3) and frequency factor (2.49 × 109–2.32 × 1017) were extracted from the fitting of different theoretical models and the values are in close agreement with each other. The value of the Avrami exponent was found ∼3 thereby indicates the occurrence of volume nucleation with two-dimensional growth in the currently studied glass system. The formation of Pure monoclinic LiZnBO3 crystalline phase is observed in 20ZnO·30Li2O·50B2O3 and 20ZnO·40Li2O·40B2O3 glass compositions which is a potential candidate for electric double-layer capacitance fabrication.

Characterization of Thermal Properties of Ruby Chocolate Using DSC, PDSC and TGA Methods

Barely explored in the prior literature, ruby chocolate was investigated in this study to explore its thermal properties. The fatty acid composition of ruby chocolate (RC) fat was determined using gas chromatography. Differential scanning calorimetry (DSC) was successfully used to determine the melting behavior and polymorphic forms of the cocoa fat and milk fat present in the RC. The oxidative stability of the fat extracted from the RC was studied with the use of pressurized differential scanning calorimetry (PDSC). The thermal behavior of the chocolate and the fat were investigated using thermogravimetry (TGA). The thermal profile and characteristics of the RC showed how the parameters compared with those of dark and milk chocolate. The melting temperature of the RC obtained by DSC was more similar to that of milk chocolate than to that of dark chocolate. Regression analysis of the PDSC data for the fat extracted from the RC was characterized by very high correlation coefficients (>0.99). It was noticed there was no statistically significant difference between the values of the activation energy (Ea) of the oxidation process for the fat extracted from the RC, obtained by the means of maximum temperature (dynamic mode) and maximum induction time (isothermal mode).

Reference Materials for the Phase Transition Temperatures (Curie Temperature) Based on Alumel, Nickel and Iron Silicide

The requirements for thermal analysis instruments are increasing in terms of their metrological support with the development of scientific and technological progress in the field of metrological supervision and electronics industry. The study of determining the phase transition temperature, namely the Curie temperature, is of particular relevance for the metrological support of the applied thermal analysis instruments and traceability to the basic physical units.The purpose of the research was to test the possibility of using materials based on alumel, nickel and iron silicide (trafoperm) as phase transition temperature standards for candidate reference materials of phase transition temperatures (RMs) traceable to the SI unit of the «temperature» value.The procedure for measuring the phase transition temperatures (Curie temperature – TC) was carried out by the thermomagnetometric method using an STA 449 F5 JUPITER thermal analyzer from the State Primary Standard GET 173-2017. The determination of the RM certified value was carried out in accordance with GOST ISO Guide 35–2015, the contributions to the uncertainty from the heterogeneity of the initial materials were evaluated, and the short-term and long-term stability of the materials were studied.A comparison of the certified values of the developed RMs with the reference values of the Curie temperature showed that they are consistent.The theoretical significance of the results obtained is proof of the possibility of using the thermomagnetometric method for the development of certified reference materials of phase transition temperatures GSO 12005–2022/GSO 12007–2022. The possibility of applying the method of differential scanning calorimetry in determining the Curie temperature was also confirmed.The practical significance of the results obtained allows expanding the possibilities for constructing the calibration dependence of measuring instruments for thermogravimetric analysis and monitoring its stability, as well as increasing the measurement precision of the Curie temperature of various substances and materials.

Use of non‐isothermal DSC in comparative studies of tin(II) systems for the ring‐opening polymerization ofd‐lactide

AbstractUnderstanding the kinetics and mechanisms of polymerization, particularly the role of a catalyst or initiator used, allows for the manipulation and control of the fabrication of new materials by the most convenient, straightforward routes. The kinetics of the bulk ring‐opening polymerization (ROP) ofd‐lactide, a useful monomer employed to control the properties of poly(l‐lactide), have been studied herein to identify a relatively quick (1 h), controlled, yet convenient route to moderately high molecular weight poly(d‐lactide). Tin(II) octoate (Sn(Oct)2), Sn(Oct)2/n‐butanol (nBuOH) and liquid tin(II) butoxide (Sn(OnBu)2) as initiating systems were investigated by non‐isothermal differential scanning calorimetry (DSC). Isoconversional methods were employed to determine the activation energy (Ea) for each reaction. The results showed that liquid Sn(OnBu)2was a more efficient initiator than the commonly reported initiating systems of Sn(Oct)2and Sn(Oct)2/nBuOH in terms of producing higher polymerization rates and polymer molecular weights. High‐molecular‐weight poly(d‐lactide) (1.8 × 105 Da) with moderate dispersity (Ð = 1.3) was obtained using 0.1 mol% liquid Sn(OnBu)2as the initiator at 120 °C. This work describes the applications of non‐isothermal DSC and isoconversional methods in comparing the effectiveness of different initiators in the bulk ROP ofd‐lactide for the first time. © 2023 Society of Chemical Industry.

Physico-Chemical Study of Curcumin and Its Application in O/W/O Multiple Emulsion.

Curcuma is a world-renowned herb known for its immense health benefits. In this study, physicochemical analyses were performed on the curcumin standard sample and curcumin multiple emulsions. The emulsions were analysed for thermal and structural stability for 21 days. Confocal laser microscopy (CLSM) was performed in order to observe the emulsion encapsulation. Modulated differential scanning calorimetry (MDSC) and HPLC methods revealed a variety of curcuminoids (curcumin, demethoxycurcumin, bisdemethoxycurcumin, and cyclocurcumin) in the investigated curcumin standard. In addition, the MDSC method was found to be suitable and comparable to HPLC for determining the curcuminoid substances. The analysis of the curcumin release revealed a value of 0.18 w.% after 14 days as the equilibrium value. Furthermore, an increase in the sizes of the emulsions was observed at the end of the 21-day study. The emulsion stability index (ESI) was used to measure the stability of multiple emulsions. The ESI reached 55.8% between 7 and 21 days later. Nano droplets of the oil phase loaded with dispersed curcumin particles captured inside the water-based carboxymethylcellulose micelles were clearly observed by CLSM.

Research on Postcuring Parameters Effect on the Properties of Fiberglass-Reinforced Silicone Resin Coil Bobbin

With the growing demand for insulation parts in extreme service environments, such as nuclear power, aviation, and other related fields, fiberglass-reinforced silicone resin (FRSR) has become a popular choice due to its exceptional physical and chemical properties in high-temperature and electromagnetic working environments. To enhance the performance of FRSR molded parts that can adapt to more demanding extreme environments, the oven postcuring process parameters on thermal stability and mechanical properties of the bobbin were investigated. The curing behavior of FRSR was analyzed by using thermogravimetric analysis (TGA) and the differential scanning calorimetry (DSC) method, and the bobbins were manufactured based on the testing results. Subsequently, the bobbins were oven postcured at different conditions, and the heat resistance and mechanical properties were analyzed by TGA and tensile tests. The results revealed that the tensile strength of the bobbin increased by 122%, and the weight loss decreased by 0.79% at 350 °C after baking at 175 °C for 24 h. The optimal process parameters for producing bobbins to meet the criteria of nuclear installations were determined to be a molding temperature of 120 °C, molding pressure of 50 MPa, pressure holding time of 3 min, oven postcuring temperature of 175 °C, and postcuring time of 24 h. The molded products have passed the thermal aging performance test of nuclear power units.

Analysis of factors affecting the determination of the degree of curing epoxy coatings of oil and gas pipes by differential scanning calorimetry

The use of internal protective coating of steel pipes is one of the most effective and reliable ways to prevent corrosion. The most widespread coatings based on epoxy film-forming exhibit high adhesion to steel and chemical resistance to various aggressive factors. The formation of epoxy coatings is intimately connected with the interactions occurring on the metal surface, the physicochemical properties of the polymer itself and with the process of curing (polymerization), as well as with the thermophysical parameters that change during curing (glass transition temperature, degree of curing). The method of differential scanning calorimetry is widely used in practice to determine glass transition temperature which provide detecting phase transitions and their values in different materials. The accuracy of this method depends on many factors related to the instrument properties and methodological approaches which leads to a lack of repeatability and reproducibility of test results in various laboratories, and as a result, to the absence of a unified criteria for assessing the quality of protective coatings. We present the results of studying the degree of curing the epoxy coatings of oil and gas pipes by differential scanning calorimetry. The effect of instrumental conditions for laboratory tests, sample preparation methods, and methods of data processing by specialized software on the determination of thermophysical properties of epoxy coatings by differential scanning calorimetry was revealed. The results obtained can be used in developing a refined procedure for determining the degree of curing protective coatings.

The interaction of triglycidyl phosphate with europium nitrate and properties of obtained metal-containing polymer

The interaction of phosphorus-containing epoxy trifunctional monomer – triglycidyl phosphate (TGPhT), with europium (III) nitrate hexahydrate is studied. A dissolution of europium salt added into TGPhT is occurred due to the interaction of the cation with phosphoryl groups and oxygen atoms of the epoxy ring, that is accompanied by the opening reaction and led to the formation of a polymer. The interaction of triepoxide with salt is investigated by FTIR-spectroscopy and differential scanning calorimetry (DSC). The thermal stability of the samples is determined by combined method of thermogravimetry and differential scanning calorimetry (TG/DSC), coupled with a quadrupole mass spectrometry to identify the gaseous products evolved during the thermal analysis of the samples. The kinetic parameters of the curing reaction are computed by using Thermokinetics software. The interaction of TGPhT with europium nitrate is suggested to occur through opening of epoxy rings in the presence of europium ions via the mechanism of cationic polymerization. The cured epoxy polymer exhibits luminescent properties.

Certified Reference Materials for Phase Transition Temperatures of Organic Substances On the Basis of Anhydrous Sodium Acetate and Sodium Methansulfonate

The requirements for thermal analysis instruments are increasing in terms of increasing the measurement ranges and improving their accuracy due to the development of scientific and technological progress in the field of metrological supervision, chemical and pharmaceutical industries. The study of determining the melting point of organic substances is of particular relevance for the metrological support of the applied thermal analysis instruments and traceability to the base units of physical quantities.The purpose of the research was to test the possibility of using organic substances on the basis of sodium acetate and sodium methanesulfonate as phase transition temperatures standards for candidate material to certified reference materials for phase transition temperatures (CRMs) traceable to the SI unit of the «temperature» value.The procedure for measuring the phase transition temperatures (melting point) was performed by differential scanning calorimetry using an STA 449 F5 JUPITER thermal analyzer from the GET 173–2017 State Primary Standard. The determination of the CRM certified value was performed in accordance with GOST ISO Guide 35–2015, the contributions to the uncertainty from the heterogeneity of the starting materials were evaluated, and the short-term and long-term stability of the materials were studied.The obtained metrological characteristics of the investigated batch of CRMs are as follows: the range of permissible certified characteristics of the melting point of the phase transition for anhydrous sodium acetate (328.35–330.35) °C, for sodium methanesulfonate (352.05–354.05) °C. Comparison of the certified melting point values of the developed CRMs with the reference melting point values presented in IUPAC showed that the certified characteristics of the CRMs are consistent within ±1.4 °C.The theoretical significance of the obtained results lies in the proof of the possibility of applying the method of differential scanning calorimetry for the development of certified reference materials for phase transition temperatures (a set of TPKR CRMs) GSO 11928–2022/GSO 11929–2022.The practical significance of the results obtained makes it possible to expand the possibility of establishing and controlling the calibration dependence of thermal analysis measuring instruments; certification of measurement procedures (methods) and accuracy control of the measurement results of the phase transition temperatures of metals, metal salts, metal oxides, polymeric materials, organic and inorganic substances.

Formation Damage Caused by Wax Deposition Results in Shale Production Decline

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 210414, “First Evidence for Shale Production Decline as a Result of Formation Damage Caused by C60+ Paraffin Wax Deposition: A Permian Case Study,” by Amir Mahmoudkhani, SPE, Locus Fermentation Solutions, and Jonathan Rogers and Martin Shumway, SPE, Locus Bio-Energy Solutions, et al. The paper has not been peer reviewed. _ Analysis of production decline curves revealed that three candidate wells in West Texas depleted faster than indicated by a type decline curve, indicating a potentially abnormal permeability-reduction mechanism. A biosurfactant-based squeeze program was recommended and applied in three horizontal wells. The biosurfactant treatment offers an alternative and economical method for remediation of formation damage caused by high‑molecular‑weight paraffin wax deposition in porous media that does not require costly intervention techniques to apply. Introduction The Bone Springs horizontal oil play in the Delaware Basin spans from southeast New Mexico into West Texas. Stacked, multipay reservoirs, each with diverse rock properties, possess upside but also complexity. The initial targets in the play were conventional sandstones. Wells then tapped into carbonate lenses and, ultimately, low-permeability sandstones. As a result of horizontal drilling technology combined with hydraulic fracturing, very thin sands and other facies are now being produced. Generally, reservoir quality of this unconventional hydrocarbon system is controlled by carbonate content, where increased carbonate content typically is associated with lower productivity. Experimental Methods All crude oils exhibited precipitation of organics at ambient laboratory temperatures. Even after storing crudes at the bottomhole temperature of 140°F, a small amount of wax remained insoluble in bulk liquid. Samples of formation drill cuttings were received for various depth intervals between 8,500 and 12,000 ft. X‑ray diffraction analyses of solids revealed quartz as the major mineral phase, with clays and carbonates account for remaining phases. Combined fractions with 160-micron size were used for microcolumn oil-recovery screening tests. Carbon distributions of oils and waxes were performed by high-temperature gas chromatography (HTGC). The Du Noüy ring method was used to measure static surface tensions of biosurfactant solutions at different concentrations and was applied to calculate critical micelle concentrations at ambient temperature. Interfacial tension (IFT) measurements were performed using a drop-shaped tensiometer using the pendant-drop method. Finally, the IFTs of oil in synthetic formation water and in biosurfactant solutions prepared in city tap water were determined. Contact-angle measurements also were performed. The wax-appearance temperature (WAT) of crude and wax samples was determined by the differential scanning calorimetry method. Spontaneous imbibition experiments were performed using the Amott-cell method at reservoir temperature. Berea sandstone core plugs (25×50 mm) with a permeability of 385 md and porosity of 18.4% were used. Core plugs were saturated with homogenized crude oil samples at 140°F for 7 days.

Study on Recycling of Waste Glass Fiber Reinforced Polypropylene Composites: Examination of Mechanical and Thermal Properties

This study presents the preparation of short glass fiber reinforced polypropylene (PP/FG) composites using with waste (post-consumer) polypropylene composite containing long glass fiber (PP/LFG) obtained from the recycling of battery covers of trucks. Waste PP/LFG composite parts were mechanically grinded before adding to PP/FG composites. An injection molding machine was used to produce the PP/FG composite test samples loading with recycled waste PP/LFG composite in the range of 1-20% by weight. Effects of recycled waste PP/LFG content on the mechanical, thermal, and morphological properties of the PP/FG composites were investigated. The following three different tests, at various waste PP/LFG ratios, were conducted: Izod/Charpy Impact test, bending test, and tensile test. Mechanical test results showed that mechanical strength of prepared PP/FG composites were not influenced by content of waste PP/LFG material up to 10 wt.%. Differential scanning calorimetry (DSC) was used for the evaluation of thermal parameters such as melting point and crystallization temperature of the polymer matrix in the composites studied. Furthermore, by analyzing the values of thermal effects determined using the DSC method, it was possible to determine the degree of crystallinity. The DSC results showed that crystallinity %, melting, and crystallization temperatures of PP/FG composites were not influenced to adding waste PP/LFG at different ratios. The morphology of composite materials was investigated by SEM analysis. Good fiber dispersion was observed in the PP matrix for PP/FG composites containing short glass fiber prepared with all ratios of recycled waste PP/LFG material containing long glass fiber.

Sequence of phase transformations in metastable β Zr–12Nb alloy studied in situ by HEXRD and complementary techniques

Phase transformations in a metastable beta Zr–12Nb alloy were investigated by high-energy X-ray diffraction (HEXRD) measured simultaneously with thermal expansion in situ during linear heating from room temperature to 800 °C. Complementary in-situ methods of electrical resistance and differential scanning calorimetry, which were performed using the same heating conditions as in the HEXRD experiment, provided additional information on the transformation sequence occurring in the Zr–12Nb alloy. Two bcc phases with a different lattice parameter, βZr and βNb, were observed in the investigated temperature range and identified using the phase diagram of the Zr–Nb system. In the initial solution-treated condition, metastable βZr phase and athermal ω particles are present in the material. At about 300 °C, Nb-rich βNb phase starts to form in the material and the original βZr phase gradually disappears. Ex-situ observations of the microstructure using transmission electron microscopy revealed a cuboidal shape of the ω particles, which is related to a relatively large misfit between the ω and β phases. At 560 °C, ω solvus was observed, identified by an abrupt dissolution of ω particles which was followed by growth of the α phase.

Synthesis and thermal characterization of porous polymeric microspheres functionalized with thiol groups

The paper presents a method of the preparation and functionalization of polymer microspheres consisting of glycidyl methacrylate (GMA) and crosslinking agents: 1,4-dimethacryloyloxybenzene (1,4DMB) and trimethylolpropane trimethacrylate (TRIM). Poly(GMA-co-1,4DMB) and poly(GMA-co-TRIM) microspheres were obtained by seed swelling polymerization. To introduce thiol groups into the microspheres structure, the reaction with thiocarboxylic acids was performed. The chemical structure of parent and modified microspheres was confirmed by FTIR and Raman spectroscopy. Elemental composition of microspheres after functionalization was determined by elemental analysis. The analysis showed the percentage of sulfur in the range of 2.78–4.51%, which corresponds to a concentration of thiol group in the range of 0.87–1.41 mmol g−1. Additionally, the porous structure of the copolymers was investigated using the low-temperature nitrogen adsorption–desorption method. The starting microspheres are characterized by a specific surface in the range of 150–160 m2 g−1, whereas functionalized copolymers indicate slightly lower surface area, of about 130 m2 g−1. The thermal stability of the materials was determined by the method of differential scanning calorimetry and thermogravimetric analysis. The course of the thermal degradation under oxidative conditions of modified microspheres is different from the starting copolymers. The functionalized microspheres showed much higher thermal stability (approximately 270 °C) compared to the starting microspheres (230–250 °C).

Diacid esters of 1-dodecanol as new alternatives to solid-liquid phase change materials for solar heat storage systems

ABSTRACT Ester-based phase change materials for heat storage have been an origin of interest for the last 2 decades due to their ease of production, different temperature options offered by the product, and the solutions they offered for the handicaps in the potential fatty acid and fatty alcohol thermal energy storage materials. In this study, synthesis, and characterization of 1-dodecanol esters of adipic acid, succinic acid, and oxalic acid were carried out. The novel esters were proven by proton nuclear magnetic resonance (1H-NMR) and Fourier transform infrared (FT-IR) spectroscopy techniques. In addition, the thermophysical properties of the synthesized esters were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods. The produced diacid esters of 1-dodecanol showed interestingly original behaviors that they melted (and crystallized) at 32.3 (30.3) oC , 30.5 (26.7) ℃, and 36.4 (33.0) ℃ which are higher than melting (and crystallization) temperatures of 1-dodecanol at 20.6 (20.6) ℃. Therefore, these compounds may have some specific applications like solar thermal storage.