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The electrocaloric heat production in BaTiO 3 -based multilayer ceramic capacitors with Y5V specification was measured in a direct way by means of an adiabatic calorimeter setup. Applying an electric field of 30 MV m - 1 is found to result in a heat release of 0.94 J g - 1 and an electrocaloric temperature change of 0.46 K, in good agreement with direct results in previous studies. [ABSTRACT FROM AUTHOR]

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and nitrocellulose/nitroglycerine (NC/NG) possess good energy properties, which were widely used in propellants, explosives and pyrotechnics. They are easy to contact with each other during their application and storage. However, their thermal characteristics under continuous heat flow have not been reported yet. Therefore, it is of great practical significance to study the thermal properties of TKX-50/NC/NG (mixture of TKX-50 and NC/NG). In this paper, the thermal characteristics and pressure behaviors of TKX-50/NC/NG, TKX-50 and NC/NG were characterized by high pressure differential scanning calorimetry (HPDSC) and adiabatic scanning calorimetry (ASC). The results showed that TKX-50 and NC/NG can promote each other to decompose under continuous heat flow, especially the thermal decomposition which affected by gases generation and heat feedback was more violent in the confined space. The decomposition peak temperature of TKX-50/NC/NG shifted to low temperature when the heat loss was ignored and the removal of decomposition gas was suppressed. The possible decomposition mechanism of TKX-50/NC/NG was speculated. It was considered that the intermediate products of TKX-50 and NC/NG decomposition under thermal stimulation would react with each other, which promoted TKX-50/NC/NG decomposition in one step at lower temperature. Thus, TKX-50 has high reactivity and high potential risk after contact with NC/NG under continuous heat flow. TKX-50 is not suitable for application with NC/NG. This study provides a reference for the structural design of nitrogen rich explosives and further broadens the researchers’ understanding of the application of TKX-50.

[Display omitted] • Determination of the specific enthalpy, the specific heat capacity and the heat of transition of six n-alkanes (n = 15 to n = 20), providing very high precision and absolute accuracy and temperature resolution. • Adiabatic scanning calorimetry with very low scanning rates of a few mK/min. • Simultaneous results for the specific heat capacity and the specific enthalpy. • Accurate determination of the heats of transition and enthalpy steps at order–disorder transitions. • Detailed comparison between adiabatic scanning calorimetry and literature results from adiabatic step calorimetry and differential scanning calorimetry. In this work, a Peltier-element-based adiabatic scanning calorimeter was used to investigate, with high-resolution and accuracy, the temperature dependence of the specific heat capacity and specific enthalpy difference of a series of linear alkanes. More specifically, results are reported for the even n-alkanes; namely n-eicosane, n-octadecane, n-hexadecane and for the odd n-alkanes, namely n-nonadecane, n-heptadecane and n-pentadecane. The measurements cover a temperature range from well in the crystalline solid phase across the solid–solid transitions (when present) in to the liquid phase across the melting transition. Accurate transition temperatures and heat of transitions were derived from the direct experimental data in view of the potential use of n-alkanes as phase change materials. [ABSTRACT FROM AUTHOR]

Peltier-element-based adiabatic scanning calorimetry was used to obtain equilibrium enthalpy and heat capacity curves for pure water and water-NaCl mixtures, up to the eutectic mass concentration of 23.2%, in the temperature range from -30 to $$5\,^\circ {\hbox {C}}$$ , including both the eutectic and the ordinary ice melting. From these equilibrium data, information about the transition temperatures and the heats of fusion was extracted. The transition temperatures are consistent with literature data for the phase diagram. The heats of fusion were rescaled with respect to the fraction of the sample that changes phase at each transition. These rescaled values for the eutectic transition are independent of the overall salt concentration, whereas for the ice melting there is an indication of slight decrease with increasing salt concentration. [ABSTRACT FROM AUTHOR]

Vegetable oils can undergo changes in their physical and chemical properties when they are subjected to processes such as extraction, purification, cooking, frying, or chemical modifications that are required depending on their application in the food industry. In the present research, different methods were used to determine physical, chemical, and thermal properties of avocado, sesame, extra virgin flaxseed, extra virgin olive, and grape seed oils, in order to evaluate and compare the compositional effects of each vegetable oil. By using an adiabatic scanning calorimeter, an alternative calorimetric method, the specific heat of five vegetable oils was obtained as a function of the temperature, in the range of 25-90 °C. The fatty acid profile was determined via gas chromatography. Monounsaturated acids present in avocado and extra virgin olive oil cause higher specific heat values in these oils, and the presence of polyunsaturated acids, contained mainly in extra virgin flaxseed oil, reduces the specific heat values. We found an almost linear behavior of vegetable oil specific heats, as a function of the temperature, and the slopes of these linear fits depend on the contained percentage of polyunsaturated fatty acids in the vegetable oil. The unsaturated acids are an important factor to analyze the behavior of specific heat of vegetable oils. The obtained specific heat values were compared with the estimation from the Rowlinson-Bondi equation, for specific heat of vegetable oils, giving a very good adjustment, mainly in a temperature range near to the room temperature. [ABSTRACT FROM AUTHOR]

The thermal and structural properties of starch granules of four maize genotypes (Palomero Toluqueño native maize, HS-2 commercial hybrid, L3-Q2 M09 experimental hybrid and Cacahuacintle native maize) were studied. By using adiabatic scanning calorimetry (ASC), the specific heat capacity ( c( T)) of these samples was obtained. Also, by integration of the area under the c( T) curves, the enthalpy for the starch gelatinization was determined, from which the percentage of gelatinized starch granules was obtained as a function of the temperature. From the X-ray diffraction patterns of the starch granules, the degree of crystallinity of the samples was derived. The average size of the starch granules, for the different maize genotypes, was calculated from the images obtained by Scanning Electron Microscopy (SEM). We found a correlation between the enthalpy of gelatinization and the average size of starch granules, and also between the degree of crystallinity and the average size of the starch granules. [ABSTRACT FROM AUTHOR]

A novel type of adiabatic scanning calorimeter (ASC) based on Peltier elements (PEs) is used to obtain high-resolution enthalpy and heat capacity data on the melting transition of gallium. The accuracy of the specific heat capacity and specific enthalpy is about 2 %, for a sub-mK temperature resolution. The simultaneously determined equilibrium specific heat capacity and specific enthalpy are used to determine the heat of fusion and the purity. In addition, the use of the PE-based ASC as a classical heat step calorimeter and as a constant rate (DSC-type) calorimeter is discussed. A comparison of the ASC results with literature data and DSC data shows the advantages of ASC for the study of phase transitions. [ABSTRACT FROM AUTHOR]

We report on the use of the heat transfer method, a novel surface-sensitive technique based on heat transfer through solid-liquid interfaces, to detect phase transitions of model lipid membranes. We selected the lipid DPPC because of its rich phase behavior in an experimentally accessible temperature range. The vesicles were adsorbed on nanocrystalline diamond films, known as a versatile platform material for biosensing with outstanding heat-conduction properties. Complementary Peltier-element-based adiabatic scanning calorimetry (pASC) and quartz crystal microbalance with dissipation monitoring (QCM-D) measurements were carried out to monitor the phase transitions in multilamellar and small unilamellar vesicles, respectively. The heat-transfer measurements revealed reversible jumps upon heating and cooling in the thermal resistance in the vicinity of the expected transition temperature and they agree qualitatively with molecular simulations of the thermal conductivity across a lipid bilayer. The results show the capability of the heat transfer method to detect the main phase transition in DPPC, opening new perspectives for the study of more complex lipid systems and different solid platforms. This work confirms QCM-D as a useful tool for the assessment of the structural changes upon the phase conversion and shows the capability of pASC to provide high-resolution thermodynamic information on biophysical systems. Temperature profile of the heat transfer resistance Rth during the main phase transition of a DPPC supported vesicle layer adsorbed on a hydrogen-terminated nanocrystalline diamond substrate. The arrows indicate the sense of the run: heating (red solid line) and cooling (blue solid line). [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel type of Peltier-element-based adiabatic scanning calorimeter (pASC). [•] Simultaneous high-resolution enthalpy and heat capacity data. [•] Melting transition of the reference materials biphenyl and phenyl salicylate. [•] Reliable purity analysis procedure. [ABSTRACT FROM AUTHOR]

Adiabatic scanning calorimetry was used to study four ionic liquid crystals whose phase sequences include highly ordered crystal smectic phases (crystal smectic E or T phases). The ionic liquids were based on piperidinium or morpholinium cations with long alkyl chains; the anions were tetrafluoroborate or hexafluorophosphate. High-resolution heat capacity and enthalpy data were obtained, from which the total transition heat and latent heat for the observed phase transitions were determined. All transitions displayed a non-zero latent heat and were thus found to be first order. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) are substances exhibiting phase transitions with large latent heats that can be used as thermal storage materials with a large energy storage capacity in a relatively narrow temperature range. In many practical applications the solid-liquid phase change is used. For applications accurate knowledge of different thermal parameters has to be available. In particular, the temperature dependence of the enthalpy around the phase transition has to be known with good accuracy. Usually, the phase transitions of PCMs are investigated with differential scanning calorimetry (DSC) at fast dynamic scanning rates resulting in the effective heat capacity from which the (total) heat of transition can be determined. Here we present adiabatic scanning calorimetry (ASC) as an alternative approach to arrive simultaneously at the equilibrium enthalpy curve and at the heat capacity. The applicability of ASC is illustrated with measurements on paraffin-based PCMs and on a salt hydrate PCM. [ABSTRACT FROM AUTHOR]

The phase transition behaviour of the chiral liquid crystal CE6 doped with spherical surface-functionalised CdSe nanoparticles has been examined by means of high-resolution adiabatic scanning calorimetry and polarising microscopy. The addition of nanoparticles results in an essentially stabilised blue phase III. The phase diagram is displayed upon heating and cooling and the enthalpy changes involved in the conversion between the blue phases are determined. The dispersion of functionalised nanoparticles is prominent for the stabilisation of blue phase III, which is potentially useful for applications, especially if applied on liquid crystals that exhibit blue phases close to room temperature. [ABSTRACT FROM AUTHOR]

High-resolution adiabatic scanning calorimetry has been used to study the specific heat capacity anomaly of the nitrobenzene–tetradecane mixture near its upper critical point. The analysis, which is based on a method that uses heat capacity and enthalpy data, yields a value of the critical amplitude ratio A+/ A− which is consistent with the universal, accepted one. The critical amplitude of the correlation length was derived via two-scale factor universality. All this information is compared to that reported in previous studies for nitrobenzene–alkane mixtures. [ABSTRACT FROM AUTHOR]

We have employed high-resolution calorimetric techniques in order to investigate the unresolved issue of the existence of a nematic phase for the liquid crystal dodecylcyanobiphenyl. Various heating and cooling runs were performed on dodecylcyanobiphenyl samples of different origin and their analysis did not reveal any signature of a nematic phase. The calorimetric results are presented in detail and they are additionally supported by optical polarising microscopy observations. [ABSTRACT FROM AUTHOR]

A thermal study of the liquid crystals tridecylcyanobiphenyl and tetradecylcyanobiphenyl has been performed by means of adiabatic scanning calorimetry. Both compounds exhibit only the smectic-A mesophase between the normal liquid and the crystalline phase and their phase transitions are strongly first order. A summary of the enthalpies and transition temperatures for all the smectic homologues of the cyanobiphenyl family is given, based on high-resolution measurements of the present work and previous studies. [ABSTRACT FROM AUTHOR]

In this adiabatic scanning calorimetry (ASC) study we investigated the liquid crystal 4-butyloxyphenyl-4'-decyloxybenzoate ([image omitted]) with the emphasis on the nematic-to-smectic A (N-SmA) and the nematic-to-isotropic (N-I) phase transitions. Because of the high resolution ASC technique we were able to accurately determine the latent heat of the first order N-I transition. The N-SmA transition was found to be a continuous one within the experimental resolution and the value of the effective specific heat capacity critical exponent, α, was found to be 0.23±0.01, thus between the 3D XY and tricritical value. [ABSTRACT FROM AUTHOR]

We performed Adiabatic Scanning Calorimetry (ASC) measurements on two ferroelectric liquid crystals: S-(-)-4-(2' -methylbutyloxy)phenyl 4-n-octyloxybenzoate and S-(-)-2-methylbutyl 4-n-nonanoyloxybiphenyl-4'-carboxylate. Our experiments showed that no latent heat was present for the smectic-A – smectic-C* (AC*) transition to within the experimental resolution. Therefore the AC* transition in both samples can be classified as a continuous one. By fitting the specific heat data we showed that this phase transition can be described by an extended mean-field model. [ABSTRACT FROM AUTHOR]

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and nitrocellulose/nitroglycerine (NC/NG) possess good energy properties, which were widely used in propellants, explosives and pyrotechnics. They are easy to contact with each other during their application and storage. However, their thermal characteristics under continuous heat flow have not been reported yet. Therefore, it is of great practical significance to study the thermal properties of TKX-50/NC/NG (mixture of TKX-50 and NC/NG). In this paper, the thermal characteristics and pressure behaviors of TKX-50/NC/NG, TKX-50 and NC/NG were characterized by high pressure differential scanning calorimetry (HPDSC) and adiabatic scanning calorimetry (ASC). The results showed that TKX-50 and NC/NG can promote each other to decompose under continuous heat flow, especially the thermal decomposition which affected by gases generation and heat feedback was more violent in the confined space. The decomposition peak temperature of TKX-50/NC/NG shifted to low temperature when the heat loss was ignored and the removal of decomposition gas was suppressed. The possible decomposition mechanism of TKX-50/NC/NG was speculated. It was considered that the intermediate products of TKX-50 and NC/NG decomposition under thermal stimulation would react with each other, which promoted TKX-50/NC/NG decomposition in one step at lower temperature. Thus, TKX-50 has high reactivity and high potential risk after contact with NC/NG under continuous heat flow. TKX-50 is not suitable for application with NC/NG. This study provides a reference for the structural design of nitrogen rich explosives and further broadens the researchers' understanding of the application of TKX-50. [ABSTRACT FROM AUTHOR]

• Specific heat capacity, enthalpy and latent heats of heptadecane and nonadecane. • Adiabatic scanning calorimetry (ASC) with very low effective scanning rates. • Phase diagram of melting and order–disorder transitions in C17-C19 binary mixtures. • Comparison between ASC and results from adiabatic step calorimetry and DSC. A novel Peltier-element-based adiabatic scanning calorimeter has been used to investigate the temperature dependence of the specific heat capacity and the specific enthalpy for n-alkanes heptadecane and nonadecane and for a set of their binary mixtures. The measurements have covered a broad temperature range from well into the ordered solid phase to well into the liquid phase. The analysis of the experimental data has allowed us to obtain accurate results for the phase transition temperatures, the transition enthalpies and the specific heat capacity values in the different phases. [ABSTRACT FROM AUTHOR]

The results of calorimetric studies of 5SrRNA isolated from Lupinus luteus and of tRNAPhe both in the absence and in the presence of different concentrations of cations Ca2+, Mn2+ were reported. The temperature and the enthalpy of melting were determined. Using the deconvolution method the elementary transitions were distinguished and discussed. [ABSTRACT FROM AUTHOR]