Differential Scanning Calorimetry Instrument Research Articles

Advancement Toward the Experimental Measurement of the Lead–Bismuth Eutectic Thermal Properties Using Differential Scanning Calorimetry Technique

Abstract The differential scanning calorimetry (DSC) method has recently emerged as a sophisticated and precise technique for promising contributions to the thermal analysis of various materials, including heavy liquid metal (HLM) coolants. However, there is a lack of experimental studies on the thermal properties of lead-based fluids, such as lead–bismuth eutectic (LBE) and lead–lithium eutectic, which are potential candidates for use as coolants, breeders, and neutron multipliers in advanced nuclear systems like the fourth-generation lead-cooled fast reactor. The available experimental data on the thermal properties of LBE and other lead-based fluids is limited, and the measurements have significant uncertainty. In addition, the composition of components used in the previous studies is inconsistent, and the environmental conditions were often unknown. Therefore, to fill these gaps and advance the thermal properties measurement technique for heavy liquid metal coolants, ENEA Brasimone, in collaboration with DICI-UNIPI, has installed a DSC instrument setup. The experiments performed at the installed DSC setup are focused on measuring some essential thermal properties of LBE using DSC. The experience gained from this work will facilitate the measurement of other fluids based on lead alloy, especially lead–lithium eutectic, a potential candidate for breeder, coolant, and neutron multiplier in demonstration power plant fusion reactors. This study represents the first effort to advance the DSC approach for accurately measuring the thermal characteristics of heavy liquid metals that are highly reactive, such as lead–lithium, which has significant potential in advanced nuclear systems.

Heat–Cool: A Simpler Differential Scanning Calorimetry Approach for Measuring the Specific Heat Capacity of Liquid Materials

Specific heat capacity at constant pressure cp (J K−1 g−1) is an important thermodynamic property that helps material scientists better understand molecular structure and physical properties. Engineers control temperature (through heat transfer) in physical systems. Differential Scanning Calorimetry (DSC) is an analytical technique that has been used for over fifty years to measure heat capacities with milligram size samples. For existing procedures, such as ASTM E1269−11 (2018), the accuracy of molar heat capacity measurements is typically ±2–5% relative to the literature values, even after calibration for both heat flow and heat capacity. A comparison of different DSC technologies is beyond the scope of this paper, but the causes of these deviations are common to all DSC instruments, although the magnitude of the deviation (observed and accepted) varies with instrument design. This paper presents a new approach (Heat–Cool) for measuring more accurate and reproducible specific heat capacities of materials. In addition to better performance, the proposed method is faster and typically requires no additional calibration beyond the routine calibration of temperature and heat flow, with melting point standards common to all applications of DSC. Accuracy, as used throughout this paper, means deviation from the literature. The estimated standard deviation of repeated measurements of the cp values obtained with the Heat–Cool technique typically falls in the ±1–2% range.

Sub-nL thin-film differential scanning calorimetry chip for rapid thermal analysis of liquid samples.

Differential scanning calorimetry (DSC) is a popular thermal analysis technique. The miniaturization of DSC on chip as thin-film DSC (tfDSC) has been pioneered for the analysis of ultrathin polymer films at temperature scan rates and sensitivities far superior to those attainable with DSC instruments. The adoption of tfDSC chips for the analysis of liquid samples is, however, confronted with various issues including sample evaporation due to the lack of sealed enclosures. Although the subsequent integration of enclosures has been demonstrated in various designs, rarely did those designs exceed the scan rates of DSC instruments mainly because of their bulky features and requirement for exterior heating. Here, we present a tfDSC chip featuring sub-nL thin-film enclosures integrated with resistance temperature detectors (RTDs) and heaters. The chip attains an unprecedented sensitivity of 11 V W-1 and a rapid time constant of 600 ms owing to its low-addenda design and residual heat conduction (∼6 μW K-1). We present results on the phase transition of common liquid crystals which we leverage to calibrate the RTDs and characterize the thermal lag with scan rates up to 900 °C min-1. We then present results on the heat denaturation of lysozyme at various pH values, concentrations, and scan rates. The chip can provide excess heat capacity peaks and enthalpy change steps without much alteration induced by the thermal lag at elevated scan rates up to 100 °C min-1, which is an order of magnitude faster than those of many chip counterparts.

Electrospun Fibrous Membrane with Confined Chain Configuration: Dynamic Relaxation and Glass Transition.

Thermodynamic glass transition processes of electrospun membranes were first introduced to study their dynamic relaxation nature, which is not constantly in equilibrium. The relaxation modes of electrospun membranes are slow but measurable near and above the Tg, given the stretched chain over long distances. Based on differential scanning calorimetry (DSC) experiments and the general principle of mode-coupling theory (MCT), endothermic peak temperature and relaxation enthalpy were used to analyze the relaxation process by capturing these instantaneous “arrested” structures. The short- and long-wavelength relaxation modes could be identified with different annealing times and temperatures relative to DSC-measured Tg for electrospun membranes with different molecular weights. Results clearly showed the dynamic nature of a glass transition in polymeric materials. Tp and enthalpy loss initially increased and then directly decreased with the increase in annealing time. When Ta > Tg, regardless of the size of the molecular weight, the Tp and enthalpy loss of the PLGA fibers would directly decrease, and the curves would shift toward the melted one. Combination of electrospinningand normal DSC instrument can be used to investigating the dynamic relax process through an adequately designed kinetic scanning procedure. This result can be explained by the general principle of MCT-type dynamic theory.

A machine learning based method for automatic differential scanning calorimetry signal analysis

Differential scanning calorimetry (DSC) is a powerful technique to study temperature induced phase transitions by monitoring the heat capacity changes. Traditional ways of DSC data analysis require manual baseline subtraction and peak analysis, which inevitably leads to errors caused by human bias. To tackle this long-standing challenge, we propose an automated method for DSC signal extraction and baseline estimation based on semi-supervised machine learning. We implement an exponential modified Gaussian mixture (EMGM) model to identify the signal of interest, and use the expectation–maximization algorithm to optimize the log-likelihood of the model. This method is then combined with the iterative polynomial fitting method for baseline allocation. One advantage of the method is not requiring the knowledge of the signal, as it is learned through matrix factorization. We demonstrate the method’s efficacy using three types of protein data measured by distinctive DSC instruments. It can effectively identify the signals of interest from the raw signal and perform proper baseline subtraction. Furthermore, the program can accurately obtain the thermodynamic parameters from the peak signals for thermal characterization. In summary, this work’s automated signal processing method improves the speed and accuracy of the DSC data interpretation. The code and data for this work can be found at: https://github.com/shuyu-wang/DSC_data_analysis/.

Effects of graphite oxide on thermal and electrical behaviors of coumarin‐based methacrylate copolymers: Its single chain polymer molecule via intramolecular cyclobutane formation

AbstractThe random copolymers of methyl methacrylate (MMA) and 4‐methyl‐2‐oxo‐2H‐chromen‐7‐yl methacrylate (COUMA) [poly (COUMA0.49‐co‐MMA)] (COMCOP1) and [poly(COUMA0.36‐co‐MMA)] (COMCOP2) were prepared via the conventional radical polymerization method. The copolymers were characterized by 1H‐NMR, Fourier‐transform infrared spectroscopy (FT‐IR), UV–visible (UV–vis), thermogravimetric analysis, and differential scanning calorimetry instruments. A kinetic study of the thermal decomposition of COMCOP1 and COMCOP1/GO 16 wt% was investigated using thermogravimetric analyzer with non‐isothermal methods selected for analyzing solid‐state kinetics data. The average activation energy values were calculated via Flynn Wall and Ozawa (FWO) and Kissinger‐Akahira‐Sunose models in a period of α = 0.10–0.70. The average values of activation energy obtained from Kissinger method for COMCOP1 and COMCOP1/GO 16 wt% were 94.5 and 78.4 kJ/mol, respectively, whereas, those of estimated by FWO method were 103.5 and 87.0 kJ/mol. We indicate that well‐defined single chain polymer molecule (SCPM) via intramolecular cyclobutane formation could be obtained by the intrachain photodimerization of coumarin groups during UV irradiation at 365 nm diluted solution of COMCOP1. The photodimerization of coumarin groups in the copolymer was confirmed by UV–vis, FT‐IR, and 1H‐NMR instruments. Dielectric and electrical behaviors of the composites having a semiconductor behavior filled GO were investigated. The activation energy values based on dc conductivity for COMCOP1 loaded GO 10 and 12 wt% were decreased from 0.206 to 0.069 eV. Also, the Ea values estimated for COMCOP2‐loaded GO 12 and 13.6 wt% were 0.0580 and 0.0859 eV, respectively.

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

Evolution of Fe-based intermetallic phases during homogenization of Al–Fe hypoeutectic alloy

Homogenization heat treatment is the first step in the processing of aluminium alloys, which for most alloys is carried out before any deformation process. Homogenization is performed to counteract microsegregation, which is the result of non-equilibrium solidification caused by diffusion rate differences between solid and liquid states during solidification. Special attention must also be paid to the impact of homogenization on changes in the morphology of iron-based constituents which are known to adversely affect formability. For the purpose of this work, a hypoeutectic Al–Fe alloy containing 1.1 mass/% Fe was homogenized at 600 °C for up to 12 h in an electric furnace. After the homogenization heat treatment, differential scanning calorimetry (DSC) was performed, comparing the homogenized samples with the sample in the as-cast state. The results were compared with thermodynamic calculations using Thermo-Calc software in order to determine the differences between the microstructure in the equilibrium and non-equilibrium state. All samples were analysed by optical and electron microscopy, and the intermetallic phases were qualitatively evaluated by both methods. In addition, energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) were required to determine the type of phases present in all experimental samples and a difference between the as-cast and homogenized state was found. The presence of metastable phases in the as-cast state and the transformation of such phases during the homogenization process was confirmed. A homogenization process, which lasted 12 h at 600 °C, was also performed with a DSC instrument. The experiment confirmed a greater heat transfer at the beginning of the homogenization process, which is consistent with all previous analyses. All results showed that after 10 h of homogenization the effects of non-equilibrium solidification in this alloy were sufficiently counteracted.

Investigation on the morphology, thermal properties, and in vitro cytotoxicity of the fish scale particulates filled high-density polyethylene composite

The high-density polyethylene (HDPE) and fish scale particulates are in the ratio of 10:3 (matrix 100 g:filler 30 g) which is filled and blended with thermoplastic composites and are then fabricated by the injection molding machine. In this work, the thermal energy absorption is obtained as 103.9 J g−1 that melts onset temperature at 121.75°C and melts peak temperature at 129.98°C of the specimen using differential scanning calorimetry instrument. A gradual mass degradation and decomposition of the prepared samples were analyzed from the thermogravimetric analysis. Evaluation of microstructure, surface morphology, and elemental analysis was carried out using field emission scanning electron microscope. The presence of functional groups in the polymeric materials was identified using Fourier transform infrared spectroscopy. The cytotoxicity testing of composites has been carried out using MG 63 cell line. In these studies, five different volumes of liquid extract of the prepared specimen having different concentrations (10, 20, 30, 40, and 50 μL) were allowed to interact with fresh cell culture medium for 24 h. The cell viability, cell morphology, and the levels of cytotoxicity of the composite specimen were studied as per ISO 10993:12 and ISO 10993:5 test standards. It was found that the natural fiber filled composite showed none to slight cytotoxic reactivity to MG-63 cells after 24 h contact. The cytotoxicity level of fish scale particulate filled HDPE composite material was compared with standard reactivity level and it was confirmed to have low toxic level (none to slight).

Effect of allotypic variation of human IgG1 on the thermal stability of disulfide-linked knobs-into-holes mutants of the Fc for stable bispecific antibody design.

BackgroundDisulfide-linked knobs-into-holes (dKiH) mutation is a well-validated antibody engineering technique to force heterodimer formation of different Fcs for efficient production of bispecific antibodies. An artificial disulfide bond is created between mutated cysteine residues in CH3 domain of human IgG1 Fc whose positions are 354 of the “knob” and 349 of the “hole” heavy chains. The disulfide bond is located adjacent to the exposed loop with allotypic variations at positions 356 and 358. Effects of the variation on the biophysical property of the Fc protein with dKiH mutations have not been reported.MethodsWe produced dKiH Fc proteins of high purity by affinity-tag fusion to the hole chain and IdeS treatment, which enabled removal of mispaired side products. Thermal stability was analyzed in a differential scanning calorimetry instrument.ResultsWe firstly analyzed the effect of the difference in allotypes of the Fcs on the thermal stability of the heterodimeric Fc. We observed different melting profiles of the two allotypes (G1m1 and nG1m1) showing slightly higher melting temperature of G1m1 than nG1m1. Additionally, we showed different characteristics among heterodimers with different combinations of the allotypes in knob and hole chains.ConclusionAllotypic variations affected melting profiles of dKiH Fc proteins possibly with larger contribution of variations adjacent to the disulfide linkage.

Fiber Orientation and Fillers Effects on Specific Heat of Fabric Reinforced Hybrid Epoxy Composites

In this investigation, the specific heat of four fabric reinforced hybrid composite materials with filled stratified epoxy matrix was analysed. All hybrid composite materials were made of 17 layers, for which were used carbon, aramid, glass and hybrid fabrics. The stratified filled epoxy matrix of fabric reinforced hybrid composites represents a matrix, in whose structure it was used three types of fillers mixtures between certain plies. The investigation of specific heat of hybrid composite materials was performed by using of Differential Scanning Calorimetry instrument. It was analysed the effects of fiber orientation at various angles on specific heat of fabric reinforced hybrid composites with filled stratified epoxy matrix and the influence of fillers mixtures on these thermal properties of epoxy matrix. Also, it was studied the specific heat of hybrid epoxy composites in dependence of carbon and aramid plies number in studied materials structure.

Thermal characterization of NaNO3/KNO3 with different concentrations of Al2O3 and TiO2 nanoparticles

The thermo-physical properties of NaNO3/KNO3 (solar salt) added with Al2O3 and TiO2 nanoparticles as phase change material in thermal energy storage system were investigated. Initially the Al2O3 and TiO2 nanoparticles were added to NaNO3/KNO3 (60:40) with a concentration of 1%, 3% and 5 mass% using low-energy ball mill. The differential scanning calorimetry instrument is used to measure the thermal properties of the prepared PCM composites. It is found that the phase change temperature and latent heat capacity vary with Al2O3 and TiO2 nanoparticles loading levels. When the loading is not over 3 mass% of Al2O3, the phase change temperature drops, and the latent heat capacity increases up to 23.3%. When the loading is over 3 mass% of Al2O3, the phase change temperature increases, and the latent heat capacity drops to 14.23%. A significant increase in latent heat capacity is found around 3 mass% of Al2O3 loading. When the TiO2 nanoparticle concentration increases, the phase change temperature decreases, and the latent heat capacity increases up to 32.2%. When the TiO2 nanoparticle’s concentration decreases, the phase change temperature increases, and the latent heat capacity decreases. The thermal conductivity of the composites was found to increase with the increase in the loading of nanoparticles. After adding 3% by mass of Al2O3 and TiO2 nanoparticles, the thermal conductivity was found to increase by 8.30 and 8.10%, respectively. From the characterization studies, we found that TiO2 helps to achieve the improved thermo-physical properties and heat storage characteristics for NaNO3/KNO3 which suggests their potential candidate of usage in the thermal energy storage system.

Determination of the heat of pyrolysis of HDPE via isothermal differential scanning calorimetry

Due to the complexity of solid state reactions such as cracking of polymers, it is very difficult to find the required heat of the involved reactions. In this study, using a differential scanning calorimetry (DSC) instrument, a new method is proposed to determine the heat of decomposition of polymers at constant temperatures. The integration of an isothermal DSC curve with respect to time gives the overall consumed heat by the process, which consists of two components: net heat of reaction and heat loss. Finding an effective solution to measure heat loss from DSC instrument is an important part of this new approach. The heat loss is determined as function of sample mass and operating temperature. The heat loss is employed to correct the DSC results and produce the net heat of decomposition reactions. This approach is new since, firstly, it uses high-certainty isothermal DSC measurements, and secondly, the heat loss values are calculated in the decomposition range. The procedure is employed to determine the required heat for pyrolysis of high-density polyethylene at constant temperatures of 400, 410, 420 and 430 °C, and the average value was calculated to be 1375 ± 233 kJ kg−1.

Inorganic Anions Regulate the Phase Transition in Two Organic Cation Salts Containing [(4-Nitroanilinium)(18-crown-6)]+ Supramolecules

Inorganic Anions Regulate the Phase Transition in Two Organic Cation Salts Containing [(4-Nitroanilinium)(18-crown-6)]+ Supramolecules

Simultaneous Differential Scanning Calorimetry-Synchrotron X-ray Powder Diffraction: A Powerful Technique for Physical Form Characterization in Pharmaceutical Materials.

We report a powerful new technique: hyphenating synchrotron X-ray powder diffraction (XRD) with differential scanning calorimetry (DSC). This is achieved with a simple modification to a standard laboratory DSC instrument, in contrast to previous reports which have involved extensive and complex modifications to a DSC to mount it in the synchrotron beam. The high-energy X-rays of the synchrotron permit the recording of powder diffraction patterns in as little as 2 s, meaning that thermally induced phase changes can be accurately quantified and additional insight on the nature of phase transitions obtained. Such detailed knowledge cannot be gained from existing laboratory XRD instruments, since much longer collection times are required. We demonstrate the power of our approach with two model systems, glutaric acid and sulfathiazole, both of which show enantiotropic polymorphism. The phase transformations between the low and high temperature polymorphs are revealed to be direct solid-solid processes, and sequential refinement against the diffraction patterns obtained permits phase fractions at each temperature to be calculated and unit cell parameters to be accurately quantified as a function of temperature. The combination of XRD and DSC has further allowed us to identify mixtures of phases which appeared phase-pure by DSC.

A simple method of obtaining the soil freezing point depression, the unfrozen water content and the pore size distribution curves from the DSC peak maximum temperature

A method based on measuring the maximum temperature of the peak obtained during the warming of frozen soil samples by the use of Differential Scanning Calorimetry (DSC) is proposed. The freezing point can be calculated from the peak maximum temperature by taking into account a correction due to the mass of water. The correction function can be one-time determined for a given DSC instrument and the scanning rate. The unfrozen water content curve can be determined by the transposition of variables, with the freezing point depression as the independent variable of temperature and the water content as the unfrozen water content. The method has been validated with the use of foreign results, including data from the NMR measurements. With regard to both the freezing point depression and the unfrozen water content, a very well agreement was obtained. The compatibility with the data on the freezing point depression in the Wyoming bentonite presented by Low et al. (1968) can be termed as excellent. The obtained approximation of the unfrozen water content below −5°C can be used to generate the differential pore size distribution curve (DPSD). The curves obtained in this manner are highly compatible with curves determined by the nitrogen desorption data measured at 77K with the use of the BJH method in the range of radii from 2 to 100nm.

Quantifying the Relationship between Rice Starch Gelatinization and Moisture‐Electrical Conductivity of Paddy during Soaking

AbstractThis study formulates a mathematical relationship correlating the degree of starch gelatinization (DSG) of rice to the paddy moisture‐electrical conductivity (EC) of paddy water during the soaking portion of the parboiling process. DSG values of rice were measured using differential scanning calorimetry (DSC). Paddy was parboiled by soaking at 60, 65, 70 and 75C. At each temperature paddy samples were selected at five different soaking times. Optimum soaking times for 60, 65, 70 and 75C were determined to be 240, 180, 120 and 80 min, respectively. Paddy moisture (22.43–34.93%, wet basis), EC of paddy water (1.63–2.71 mS/cm) and DSG of rice (5.38–36.90%) increased with increasing temperature and soaking time. It was found that a linear relationship exists between DSG and EC, as well as between DSG and moisture content during soaking. EC of paddy water correlates well with DSG of rice during soaking. An online measurement system of paddy water EC was manufactured and evaluated. The relationship between DSG and EC can be utilized for quick and simple determination of DSG during soaking and eliminating the need for conventional chemical analysis.Practical ApplicationsParboiled rice enjoys high popularity because of its high nutritional content. The soaking stage is the most important stage of the parboiling process. Soaking conditions (temperature and time of soaking) largely determine the characteristics of the parboiled product and can be evaluated by DSG. Therefore, from an industrial point of view, it is important to apply the best processing conditions for parboiling rough rice. Hot soaking requires precise control because starch granules are gelatinized during soaking. Determination of DSG is commonly done by DSC instrument. This method is associated with high costs and cannot provide online data. Online measurement of EC values of paddy water during soaking can be used to easily and accurately predict the final time of the soaking stage. This study was developed as a quick and easy method for online determination of DSG values during soaking. The method presented here can be used for monitoring and controlling the soaking stage by measuring paddy water EC via an online system based on DSG values during soaking.

Temperature calibration procedure for thin film substrates for thermo-ellipsometric analysis using melting point standards

Precise and accurate temperature control is pertinent to studying thermally activated processes in thin films. Here, we present a calibration method for the substrate–film interface temperature using spectroscopic ellipsometry. The method is adapted from temperature calibration methods that are well developed for thermogravimetric analysis and differential scanning calorimetry instruments, and is based on probing a transition temperature. Indium, lead, and zinc could be spread on a substrate, and the phase transition of these metals could be detected by a change in the Ψ signal of the ellipsometer. For water, the phase transition could be detected by a loss of signal intensity as a result of light scattering by the ice crystals. The combined approach allowed for construction of a linear calibration curve with an accuracy of 1.3°C or lower over the full temperature range.

Experimental Study on the Preparation Process of Binary Carbonate Salts

Ten kinds of binary carbonate salts with different ratio were respectively prepared by two kinds of preparation processes and the research on thermo-physical properties, thermal stability and component analysis was worked respectively by Differential Scanning Calorimetry instrument and XRD analytical instrument. The results showed: There was little difference on melting point and decomposition point between the samples prepared by two kinds of methods and well matched with that of reference phase diagram; For the preparation of mixed carbonate, static melting method was superior to the simple mechanical grinding method through TG and DSC curves of multiple cycles; There was no new material produced in both two kinds of preparation processes from the XRD composition analysis.

Ferroelectric Transition Vanishes in (NH4)2SO4 Precipitated in Small-Sized Aqueous Droplets

The ferroelectric transition of (NH4)2SO4 precipitated during the freezing of aqueous ammonium sulfate droplets is investigated by means of differential scanning calorimetry (DSC). Below 223 K ammonium sulfate precipitates into ferroelectric crystals from (single) millimeter-sized and (emulsified) large micrometer-sized droplets. Upon subsequent warming, the ferro- to paraelectric (F → P) transition is observed at ∼223 K. In the case of (emulsified) small micrometer-sized droplets, (NH4)2SO4 precipitates into the paraelectric phase, and the F → P transition is absent. Since the mass sensitivity of the DSC instrument is demonstrated to be high enough to resolve the possible F → P transition of (NH4)2SO4 precipitated in small-sized droplets, this suggests that (NH4)2SO4 crystals precipitated from small micrometer-sized droplets are smaller than the critical size, below which ferroelectric ammonium sulfate does not exist. We do not know the exact critical size, but from independent measurements on (NH4)2SO4 ...