Melting temperature determination

Cell A—a thin-wall capillary of the sort used in melting temperature determinations ... 

The studies discussed above gives an idea of conformational stability of proteins in ILs as inferred from the t measurement and melting temperature determination followed by various spectroscopic methods. However, stability of a protein/enzyme has contributions from both thermodynamic and kinetic parameters [55]. While thermal unfolding studies help to extract important thermodynamic parameters, stability of the proteins could also arise from the kinetic barrier to the conformational changes in the protein scaffold [55]. However, except for monellin [48], the thermodynamic stability in other cases has not been examined. Thus, in context of stability of proteins/enzymes in ILs, it is important and imperative to study and probe thermal unfolding as well as the thermodynamics and kinetics of the conformational change of the proteins in ILs. 

In the present work we address ourselves to two problems directly concerned with determining the physical quantities required for the different extrapolations. The first of these is concerned with the relation of the melting temperature determined by differential calorimetry to the true melting temperature. The other involves an analysis of melting-recrystallization during a DSC scan and its influence on the observed melting temperature. 

The morphology of the phases and the glass transition or melt temperatures determine the final properties of the blend (Table 35-3). 

Fig. 9. Temperature-concentration phase diagram of PVC-diethyl ma -onate gels aged for 24 h at 20 °C (O) temperatures determined from the first heating by DSC (scan speed 20°C/min bars indicate the width of the melting endotherm) and ( ) melting temperatures determined visually by the ball-drop method (heating rate 2°C/min). Eeproduced from Macromolecules [Ref. 106] by the courtesy of the authors and The American Chemical Society...

Molar ratio of Ti and polymer chain calculated from yield and Syndiotactic triad determined by C NMR Melting temperature determined by DSC Not detected... 

T maximum degradation temperatures determined from the derivatives TGA (DTGA) curves. T melting temperature determined by differential scanning calorimetry (DSC). 

The determination of the crystallization temperature of a sample is subject to many of the same considerations that apply to melting temperature determination. The crystallization temperature is normally reported as the temperature at which the exothermic peak maximum occurs but may also be reported as the temperature at which crystallization begins (the crystallization onset temperature). The observed crystallization peak temperature is always considerably lower (20°C or more) than the melting temperature observed subsequently for the same sample. The difference between the observed crystallization and melting peak temperatures increases as the rate of temperature ramp increases. 

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