Differential scanning calorimetric thermograms

Fig. 12. Differential scanning calorimetric thermogram of cimetidine hydrochloride. 

Fig. 24.3 Differential scanning calorimetric thermograms of poly ( 3 - (2 - (2 - methoxyethoxy) ethoxy) - 4 - methylthio-phene). (From Ref. 33.)...

The change of the specific heat of the transition from amorphous solid to supereooled liquid as well as the temperature dependence of the specific heat in the amorphous solid and supercooled liquid has been examined for the La-Al-Ni amorphous alloys through detailed differential scanning calorimetric measurements (Inoue et al. 1989f). As an example, fig. 115 shows the thermograms of the amorphous La5sAl25Ni2o alloy with the widest supercooled liquid region. The Cp value of the as-quenched phase is 24 J/mol K... 

Differential scanning calorimetric (DSC) thermograms, which revealed transition temperatures and heats of fusion, provided results complementary to the pNMR... 

Figure 6 Differential scanning calorimetric melting thermograms of NIE and CIE but-terfat-canola oil blends, (a) Butterfat (b) 90 10 (c) 50 50. The shaded area represents the CIE blends.

A further positive reaction to this dramatic incident took place in the central research department of the company. A physico-chemist had the idea of using his differential scanning calorimeter (DSC) to look at the energy involved in this reaction. He performed an experiment with the initial concentration and a second with a higher concentration. The thermograms he obtained were different and he realized that he could have predicted the incident (see Exercise 11.1). As a consequence, it was decided to create a laboratory dedicated to this type of experiment. This was the beginning of the scientific approach of safety assessments using thermo-analytic and calorimetric methods. From this time on, many different methods were developed in different chemical companies and became commercially distributed, often by scientific instrument companies. 

The variation of the mechanical properties near the glass transition is discussed in Chapter 12, and techniques developed to this end such as dynamic mechanical analysis (DMA) are usually employed. Figure 11.3 illustrates the shape taken by the curve that reflects the variation of the volume of a polymer sample as a function of the temperature this technique is sometimes used but in spite of the simplicity of its principle, it is delicate to handle. The calorimetric technique is preferred, especially differential scanning calorimetry (DSC). The typical shape taken by a thermogram for a noncrystallizable polymer is shown in Figure 11.6. 

---