Differential scanning calorimetry

About: Differential scanning calorimetry is a research topic. Over the lifetime, 50315 publications have been published within this topic receiving 1152335 citations. The topic is also known as: DSC.

Microwave-Solvothermal Synthesis of Nanostructured Li2MSiO4/C (M = Mn and Fe) Cathodes for Lithium-Ion Batteries

Abstract: Nanostructured Li2FeSiO4 and Li2MnSiO4 cathodes have been synthesized by a facile microwave-solvothermal synthesis. To improve crystallinity and enhance electronic conductivity, the resulting samples have been mixed with sucrose and heated at 650 °C for 6 h in argon atmosphere. The Li2MSiO4/C nanocomposites, thus, obtained have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, electrochemical measurements, and differential scanning calorimetry. The Li2FeSiO4/C sample exhibits good rate capability and stable cycle life, with discharge capacities of 148 mAh/g at room temperature and 204 mAh/g at 55 °C. Although Li2MnSiO4/C shows higher discharge capacities of 210 mAh/g at room temperature and 250 mAh/g at 55 °C, it suffers from poor rate capability and drastic capacity fade. The disparity in the electrochemical performance and redox behavior between Li2FeSiO4/C and Li2MnSiO4/C can be attributed to the differences in the structural st...

Relaxation behaviour of the amorphous components of wood

Abstract: The viscoelastic properties of mod were investigated using dynamic mechanical thermal analysis and differential scanning calorimetry. Under a limited set of conditions, two separate glass transitions (T g) could be identified with both techniques. These two transitions were identified as arising from the amorphous lignin and hernicellulose matrix in the wood cell wall. Moisture dramatically affected the temperature at which the two dispersions occurred and, consequently, the ability to resolve their independent responses. The relationship betweenT g and moisture for both components could be modelled with the Kwei equation, which accounts for the presence of secondary interactions. Annealing and specific interactions of a series of organic diluents were wed in an attempt to enhance the resolution of the two components values ofT g. Time-temperature superposition was shown to be applicable to wood plasticized with ethyl formamide, following Williams-Landel-Ferry behaviour over the temperature rangeT g toT g + 85° C. These observations allow certain conclusions to be drawn concerning the applicability of existing models of the wood cell wall's supermolecular morphology. Most notably, models of thein situ morphology of the three wood components can be limited to those which consider the amorphous matrix of lignin and hemicellulose to be immiscible.

A Comprehensive Evaluation of the Melting Points of Fatty Acids and Esters Determined by Differential Scanning Calorimetry

Abstract: The melting point is one of the most important physical properties of a chemical compound and it plays a significant role in determining possible applications. For fatty acid esters the melting point is essential for a variety of food and non-food applications, the latter including biodiesel and its cold-flow properties. In this work, the melting points of fatty acids and esters (methyl, ethyl, propyl, butyl) in the C8–C24 range were determined by differential scanning calorimetry (DSC), many of which for the first time. Data for triacylglycerols as well as ricinoleic acid and its methyl and ethyl esters were also acquired. For some compounds whose melting points have been previously reported, data discrepancies exist and a comprehensive determination by DSC has not been available. Variations in the present data up to several °C compared to data in prior literature were observed. The melting points of some methyl-branched iso- and anteiso-acids and esters were also determined. Previously unreported systematic effects of compound structure on melting point are presented, including those for ω-9 monounsaturated fatty acids and esters as well as for methyl-branched iso and anteiso fatty acids and esters. The melting point of a pure fatty acid or ester as determined by DSC can vary up to approximately 1 °C. Other thermal data, including heat flow and melting onset temperatures are briefly discussed.

Glass transition and relaxation behavior of epoxy nanocomposites

Abstract: With advances in nanoscience and nanotechnology, there is increasing interest in polymer nanocomposites, both in scientific research and for engineering applications. Because of the small size of nanoparticles, the polymer–filler interface property becomes a dominant factor in determining the macroscopic material properties of the nanocomposites. The glass-transition behaviors of several epoxy nanocomposites have been investigated with modulated differential scanning calorimetry. The effect of the filler size, filler loading, and dispersion conditions of the nanofillers on the glass-transition temperature (Tg) have been studied. In comparison with their counterparts with micrometer-sized fillers, the nanocomposites show a Tg depression. For the determination of the reason for the Tg depression, the thermomechanical and dielectric relaxation processes of the silica nanocomposites have been investigated with dynamic mechanical analysis and dielectric analysis. The Tg depression is related to the enhanced polymer dynamics due to the extra free volume at the resin–filler interface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3849–3858, 2004