Differential scanning calorimetry basics

INTRODUCTION TO DIFFERENTIAL SCANNING CALORIMETRY. BASIC PRINCIPLES AND TYPES OF DSC EQUIPMENT... 

Several collaborating laboratories (usually five participating laboratories) test the proposed substance using a variety of techniques. The relative reactivity or relative absorbance of the impurities present in a substance must be checked when a nonspecific assay method is employed, e.g. by colorimetry or ultraviolet spectrophotometry. It is particularly important to quantify the impurities when a selective assay is employed. In such a case, it is best to examine the proposed substance by as many methods as practicable, including, where possible, absolute methods. For acidic and basic substances, titration with alkali or acid is simple but other reactions which are known to be stoichiometric may be used. Phase solubility analysis and differential scanning calorimetry may also be employed in certain cases. 

A rather different study of the kinetics of decomposition of solid complexes of [VO(dbm)2(L)] (dbm = dibenzoylmethanato, L = py and several methyl-, dimethyl- and amino-pyridines) used differential scanning calorimetry (DSC).531 Using the temperature that corresponds to the loss of the molecule L in equation (37), a linear relationship was found between it and the basicity of L, except for 4-amino- and 4-methyl-pyridine. 

Spectroscopy has become a powerful tool for the determination of polymer structures. The major part of the book is devoted to techniques that are the most frequently used for analysis of rubbery materials, i.e., various methods of nuclear magnetic resonance (NMR) and optical spectroscopy. One chapter is devoted to (multi) hyphenated thermograviometric analysis (TGA) techniques, i.e., TGA combined with Fourier transform infrared spectroscopy (FT-IR), mass spectroscopy, gas chromatography, differential scanning calorimetry and differential thermal analysis. There are already many excellent textbooks on the basic principles of these methods. Therefore, the main objective of the present book is to discuss a wide range of applications of the spectroscopic techniques for the analysis of rubbery materials. The contents of this book are of interest to chemists, physicists, material scientists and technologists who seek a better understanding of rubbery materials. 

Neutral resins formulated with various xylose contents were used to bond Douglas-fir veneers into two-ply panels at 170 °C as opposed to 140 °C used for the basic resins. This temperature was chosen for bonding since differential scanning calorimetry (DSC) showed that the unmodified and modified neutral resins produce a major exotherm at about this temperature, whereas, resol resins cured under basic conditions produce an exotherm at about 140 °C. 

It was outlined in chapter 2 in detail that screening tests primarily have the purpose, to provide a first characterization of the safety relevant substance properties as part of the basic assessment. It was further explained that the determination of the thermal stability of a substance is of the greatest importance. The most fi-equently used methods for this puipose are those that investigate thermal stability using very small amounts of sample material only. The most widely used test equipments to perform such investigations are the DTA ( difference thermal analysis ) and DSC ( differential scanning calorimetry). 

This concludes the discussion of thermometry and dilatometry. The tools to measure temperature, length, and volume have now been analyzed. The tools for measurement of heat, the central theme of this book, will take the next three sections and deal with calorimetry, differential scanning calorimetry, and temperature-modulated calorimetry. The mechanical properties which involve dilatometry of systems exposed to different and changing forces, ate summarized in Sect. 4.5. The measurement of the final basic variable of state, mass, is treated in Sect. 4.6 which deals with thermogravimetry. 

The Basics of Modulated Temperature Differential Scanning Calorimetry... 

PLCL (50 50) copolymers were basically random and amorphous. However, two values of were observed by differential mechanical analysis (DMA) and maybe also by differential scanning calorimetry (DSC) thermograms (Fig. 3.6 Jeong, 2004a). Furthermore, micro domains (about 17 nm size) were indicated on SAXS profile and finally confirmed by transmission electron microscopy (TEM) (Fig. 3.7). Therefore, the PLCL copolymer was probably composed of a soft matrix of mainly caprolactone moieties and... 

The basic characteristics of these segmented copolymers were studied using several techniques. These techniques included fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), intrinsic viscosity (IV), and differential scanning calorimetry (DSC). 

The basic methods for the determination of phase transition temperatures (7 ) are DSC (differential scanning calorimetry), DTA (differential thermal analysis), and polarization microscopy. Every method has its advantages and restrictions. DSC allows one to determine the enthalpies of phase transitions (A// ). Microscopy allows one both to determine the phase transition temperatures and to identify the t)fpe of mesophase. DTA gives reliable results for melting temperatures of LCs that show solid-state polymorphism, and of LC mixtures. The differences in that can be found in publications by different authors arise from different measurement techniques and the presence of impurities. We have selected the data with the higher 7 values in such cases. 

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