Use Of Differential Scanning Calorimeter Research Articles

Synthesis and liquid crystal properties of a new class of calamitic mesogens based on twin 1,3,4-thiadiazole derivatives with imine linkage

The synthesis and characterization of two distinct novel series of compounds, [II]n and [V]n , containing 1,3,4-thiadiazole units, were studied in this work. The central core of the first series is phenyl, whereas the central core of the second series is OCH2CH2O. FTIR,1HNMR,13CNMR, and mass spectroscopy are used to characterize the materials used in this investigation. Liquid crystalline properties were confirmed by the use of differential scanning calorimeter (DSC) and hot-stage polarizing optical microscopy (POM). While other compounds showed no liquid crystalline behavior, the compounds [II]3 –[II]6 , [V]1 and [V]n showed enantiotropic nematic and smectic phases.

On the Study of Thermal Transitions in Selected n-Paraffins Using Differential Scanning Calorimetry

The results obtained from a study of the thermal transformations of polymorphic long-chain normal paraffins (n-C32H66 and n-C36H74) are presented here. The research was performed using a power-compensated Differential Scanning Calorimeter (DSC). Both heating and cooling experiments were performed in dynamic nitrogen atmosphere. Thermodynamic data for both polymorphic transitions, as well as the fusion endotherms, were determined from the DSC thermal curves. Using the heats of transition (∆H), in Joules/gram, obtained from the data in the DSC thermal curves, molar heats of transition (∆H), in kJ/mol, were calculated and compared to previously published values. The molar entropy of transition (∆S) was then calculated for each of the observed thermal events. Additional information is given by the author on obtaining the best results from the use of DSC for the thermal behavior of n-paraffins. This manuscript opens with a review of most of the early work and the results it provided dealing with polymorphism of n-paraffin solids. Some of this referenced work was performed prior to the advent of computerized analytical instrumentation.

Thermophysical Characteristics of VCO-Soybean Oil Mixture as Phase Change Material (PCM) using T-History Method

Phase change material (PCM) is widely used as thermal storage in various fields. Various successes of implementing PCM have been proven. The use of PCM in some systems can reduce electricity consumption. Energy storage utilizes latent heat of material that is larger than sensible heat. In order for a material to be used as thermal storage, it is necessary to know the thermophysical characteristics of the PCM material. A general method for knowing thermophysical characteristics by using Differential Scanning Calorimeter (DSC). The use of DSC has limitations such as the sample used is too little so that the characteristics of the material produced will be very different compared to using the bulk material. The T-history method has the advantage of using large samples and can be done easily. In this study, the T-history method was used to determine the thermophysical characteristics of the material. PCM used is a mixture of Virgin Coconut Oil (VCO) - soybean oil for the application of thermal storage in air conditioners. The mixture of VCO-soybean oil used is 5% and 20% soybean oil in VCO.

Measurement of thermal properties of white radish (R. raphanistrum) using easily constructed probes.

Thermal properties are necessary for the design and control of processes and storage facilities of food materials. This study proposes the measurement of thermal properties using easily constructed probes with specific heat capacity calculated, as opposed to the use of Differential Scanning Calorimeter (DSC) or other. These probes were constructed and used to measure thermal properties of white radish in the temperature range of 80–20°C and moisture content of 91–6.1% wb. Results showed thermal properties were within the range of 0.71–0.111 Wm-1 C-1 for thermal conductivity, 1.869×10−7–0.72×10−8 m2s-1 for thermal diffusivity and 4.316–1.977 kJ kg-1C-1for specific heat capacity. These results agree with reports for similar products studied using DSC and commercially available line heat source probes. Empirical models were developed for each property through linear multiple regressions. The data generated would be useful in modeling and control of its processing and equipment design.

Martensitic transformation and shape memory effect in NiTi alloy covered by chitosan/silver layer

The NiTi shape memory alloy was covered with chitosan/silver layer. Coatings were deposited at room temperature using combination of processing parameters such as deposition voltage and amount of silver in colloidal suspension. Structure of layers was studied by means of X-ray diffraction. Quality of the coatings was evaluated basing on observations done in scanning electron microscopy. Transformation behaviour of coated samples was studied with use of differential scanning calorimeter. The covered sample revealed presence of the reversible martensitic transformation and ability to deformation (in bending mode) up to 8%. Forward martensitic transformation, in as-received NiTi alloy and in alloy after layer deposition occurred in two steps B2-R-B19’. After deformation quality of the chitosan/silver layer remained unchanged.

Oxidation kinetics and melting profiles of the structured lipids used in infant cookies

In this study, fats extracted from cookies for infant and structured lipids of milkfat (MF), rapeseed oil (RSO), and concentrate of fish (ROPUFA) oil used to bake these cookies were oxidized. The experiments were done at five different heating rates with the use of differential scanning calorimeter (DSC). The onset oxidation temperature (Ton, °C) was determined as the intersection of the extrapolated baseline and the tangent line (leading edge) of the recorded exotherm. The kinetic parameters of the oxidation process (activation energy, pre‐exponential factor, and reaction rate constants) were calculated using the Ozawa–Flynn–Wall method and the Arrhenius equation. The activation energy for analyzed lipids ranged from 91.97 to 199.71 kJ/mol and the pre‐exponential factors ranged from 1.82 × 1011 to 4.11 × 1022 min−1. Fat extracted from cookies was characterized by a better oxidative parameters than fat used to bake them. In the experiment, the melting characteristic of structured lipids in comparison to the starting mixture was also done. The melting curves were recorded by DSC. The results indicate that structured lipids are complex mixtures of various TAGs with wide‐ranging melting points.Practical applications: The kinetic parameters obtained in this paper are thermodynamically and kinetically consistent and can help to predict oxidative stability of interesterified fats‐based products. The use of DSC method seems to be suitable for predicting the shelf life of the cookies intended for infants and children. It also saves a lot of time, which is very precious in quality control.Lipase‐catalyzed interesterification of milk fat, rapeseed oil, and concentrate of fish oil at weight ratio 4:5:1 was performed for producing structured lipids intended as fat to bake cookies for infant and young children. The melting characteristics of TAGs fractions for starting mixture and structured lipids was done using DSC. The mixture of MF, RSO, and ROPUFA before interesterification exhibited a four peaks. Interesterification produced noteworthy changes in the melting profile, whereas blending alone resulted in a dilution effect. All exhibited a wide melting range, with four distinct peaks. The kinetic parameters of the oxidation process (activation energy, pre‐exponential factor, and reaction rate constants) were calculated using the Ozawa–Flynn–Wall method and the Arrhenius equation. Fat extracted from cookies was characterized by a better oxidative parameters than fat used to bake them.

現場重合型ポリアミド６をマトリックスとするＧＦＲＴＰの機械的特性に及ぼす成形条件の影響

The effect of molding conditions on the mechanical properties of glass fiber reinforced in situ polymerizable polyamide6 matrix (I-GFRTP) were investigated by the use of differential scanning calorimeter (DSC), three-point bending tests and Izod impact tests for various types of the composites which were molded at temperatures of 140, 160, 180 and 200°C respectively. The three-point bending test at 160°C revealed the highest strength within all the specimens tested. For Izod impact tests, no correlation between the molding temperatures and Izod impact strength was observed. Furthermore, it was shown that although I-GFRTP has a higher crystallinity than GFRTP of which matrix is PA6 that has already polymerized, impact strength of I-GFRTP is on a level with that of GFRTP.

A New Technique for Using DSC Melting Endotherms to Study Isothermal Bulk Crystallization of Semicrystalline Polymers at Low Degrees of Undercooling: Syndiotactic Polypropylene1*

In this manuscript, we present a new technique for using a differential scanning calorimeter (DSC) to study isothermal bulk crystallization and the kinetics of the process at “high” crystallization temperatures or “low” degrees of undercooling. It is based on measurements of the enthalpy of fusion from the subsequent melting endotherms after isothermal crystallization for various time intervals. Syndiotactic polypropylene (s–PP) was used as the model system. The benefits of the new technique, based on the results we present here, are threefold: (1) it allows an accurate determination of the induction time; (2) it offers a means to extend the use of DSC to obtain kinetics parameters for isothermal crystallization at temperatures at which the traditional technique is not applicable; and (3) it gives an insight into certain mechanistic aspects of the isothermal crystallization process as it occurs at different crystallization time intervals. *This manuscript is dedicated to the memory of Professor Donald C. Bogue.

Physical Aging and Light Scattering of Low-Loss Poly(methyl methacrylate) Glass

Isothermal aging has been carried out on low-loss poly(methyl methacrylate) (PMMA) glass at 18°C below the glass transition temperature (Tg). The effect of enthalpy relaxation on light scattering loss of PMMA glass which had no excess scattering was investigated by the use of differential scanning calorimeter (DSC) and light scattering measurement. The light scattering intensity of PMMA glass did not increase with increasing aging time. It is seen that the light scattering loss of glassy PMMA is not affected inherently by physical aging as a result of its approach to thermodynamic equilibrium at a temperature 18°C below its Tg.

The Use of DSC to Study the Effects of Solutes on Heterogeneous Ice Nucleation Kinetics in Model Food Emulsions

Effects of sucrose, D-alanine (amino acid with hydrophobic residue) and potassium nitrate on heterogeneous ice nucleation kinetics were studied with a differential scanning calorimeter (DSC) in a model food emulsion by employing different solute concentrations and ice nucleants: silver iodide (AgI) and Pseudomonas syringae. Heterogeneous nucleation rates were described with a mathematical expression in the same form as suggested by the classical homogeneous nucleation theory. Temperature effects on these rates were an exponential function of a parameter defined in terms of the reduced temperatures. Our results have confirmed that the type of the nucleation template was important in determining the temperature effects of the solutes on the heterogeneous nucleation rates. In the experiments with AgI, values of the model parameters were generally larger then those of the corresponding experiments with P. syringae. Observations with AgI/30 g/100 g sucrose solutions indicated extremely high parameter values which might be caused by the change of the catalytic site of AgI molecules and variation of the emulsion properties by highly concentrated sucrose. With the P. syringae / D-alanine and AgI / D-alanine systems only modest changes were observed in the model parameters with changing D-alanine concentrations. Experimental data with the P. syringae / KNO3 system suggested that the heterogeneous ice nucleation rates might be affected by denaturation of catalytic site proteins of P. syringae at high salt concentrations.

Characterization of Tricresylphosphate Lubricating Films by Micro-Fourier Transform Infrared Spectroscopy

The characterization of tricresylphosphate (TCP) lubricating film by use of micro-Fourier Transform Infrared Spectroscopy (μ-FTIR) is reported. The study uses a combination of test methods to establish the qualitative sequence of chemical reactions that result in the formation of the observed anti-wear film. A four-ball wear tester, using a 6 μl test procedure, was used to generate the tribochemical films. A static pressurized Differential Scanning Calorimeter (DSC) was used at several temperatures to obtain TCP-iron reaction products similar to those formed under rubbing conditions. The wear contact temperatures can be estimated by comparison of the μ-FTIR spectra of the static reaction products to the spectra from the wear tests conducted at room temperature. The combination of the FTIR and DSC proved to be a powerful, rapid and reliable analytical tool. The use of DSC as a static reactor and the four-ball wear tester as a sequential test procedure provided the necessary materials for FTIR analyses. The...

Use of DSC as a quality control tool

AbstractA differential scanning calorimeter (DSC) has been found to be a very useful quality control tool for a manufacturer of rigid PVC products. It is particularly good at measuring the consistency of lubricants such as paraffin waxes, and ethylene bis‐stearamide. Test results are presented which clearly show the difference between two paraffin waxes, both of which were considered identical from normal wax specifications, but which performed differently in production equipment. Also presented are the statistics used to draft raw material specifications which include DSC measurements.