Thermograms

Thermogravimetry The products of a thermal decomposition can be deduced by monitoring the sample s mass as a function of applied temperature. (Figure 8.9). The loss of a volatile gas on thermal decomposition is indicated by a step in the thermogram. As shown in Example 8.4, the change in mass at each step in a thermogram can be used to identify both the volatilized species and the solid residue. 

Fig. 5. Differential scanning calorimetry thermogram. Amorphous PPS is heated from room temperature to 325°C at 20°C/min.

Fig. 10. Differential scanning calorimetry thermogram of a thermoset. The reaction order is 1.83, = 95 kJ/mol (22.7 kcal/mol), and the heat of...

In a testing context, it refers to the first detection of exothermic-activity on the thermogram. The differential scanning calorimeter (DSC) has a scan rate of I0°C/min, whereas the accelerating rate calorimeter (ARC) has a sensitivity of 0.02°C/min. Consequently, the temperature at which thermal activity is detected by the DSC can be as much as 50°C different from ARC data. 

Polyetherimides show no crystallinity as evidenced from calorimetry measurements. The heteroarylene like phenylquinoxaline [27], oxadiazole [30], and benzoxa-zole [56] activated polyethers show TgS from DSC thermograms, with no evidence of crystallization, indicating amorphous or glassy morphology. Furthermore, wide angle x-ray scattering measurements show no evidence of crystalline or liquid crystalline type morphologies, consistent with an amorphous structure. F polyether... 

The heat of fusion of the rotator phase in n-paraffms is 38-40 cal/g, while AHo- m for PE irradiated with 1000 Mrad is about 29 cal/g. The corresponding value of AHo->m for hexagonal PE at high pressure (500 MPa) is only around 15 cal/g. Thermograms of constrained PE fibers showed similarly low heats of fusion of the hexagonal phase. 

In the PP-PA system, the DSC thermograms showed two peaks corresponding to nylon and PP. For the compatibilized system the crystallization peak of nylon remains unaltered, while that of PP shifted toward a higher temperature in the case of PPacr, and for PPmal, the shift was to lower temperatures (Fig. 1). This may be due to the fact that PPacr was acting as the nucleating agent. The average crystallinity of the blend was also decreased by the incorporation of compatibilizer. The mechanical properties of these blends was improved by the addition of PPmal and PPacr as compatibilizers (Table 1). 

Homopolymerization of macroazoinimers and co-polymerization of macroinimers with a vinyl monomer yield crosslinked polyethyleneglycol or polyethyleneglycol-vinyl polymer-crosslinked block copolymer, respectively. The homopolymers and block copolymers having PEG units with molecular weights of 1000 and 1500 still showed crystallinity of the PEG units in the network structure [48] and the second heating thermograms of polymers having PEG-1000 and PEG-1500 units showed that the recrystallization rates were very fast (Fig. 3). 

Figure 3 DSC thermograms for (a) homopolymer of an ester type macroazoinimer, MAIM-1000, having PEG-1000 units and (b) styrene-PEG-1000 crosslinked polymer with MAIM-1000. Source Ref. 50.

Figure 16-27. DSC thermograms of Oocl-OPV5 (left) and Oocl-OPV5-CN (right), recorded on a Perkin Elmer 7 scries (hernial analysis system at healing and cooling rales of 10 C mill"1.

The coexistence of two types of structures in transparent polyethylene filaments obtained by Porter and co-workers47 by forcing the melt through a capillary was proved by the existence of two peaks in the thermogram a high-temperature peak for ECC and a low-temperature peak for FCC (cf. Fig. 8 c). 

Lead Methoxy Picrate. C7HsN309Pb, mw OFbOH 482.35, N 8.71%, dark yel polycryst solid mp, when heated it decomps with a. loud crack on slow decompn in a DSC app, the thermogram displayed a small endotherm at 207° and a prominent exotherm at 247° which marked its decompn impact sensitivity, 4" (10% value, PicArsn app,... 

Triethanolamine salts of alcohol sulfates form white crystals when obtained in pure form after recrystallization. At their melting point they are semisolid with gelatinous appearance and the transition is difficult to detect. Melting points, determined through thermograms obtained by differential scanning calorimetry, gave 72, 76, 80, and 86°C for dodecyl, tetradecyl, hexadecyl, and octadecyl sulfates, respectively [63]. 

The output of a differential scanning calorimeter is a measure of the power (the rate of energy supply) supplied to the sample cell. The thermogram in the third illustration shows a peak that signals a phase change. The thermogram does not look much like a heating curve, but it contains all the necessary information and is easily transformed into the familiar shape. 

A thermogram from a differential scanning calorimeter. The peak indicates a phase change in the sample, and the difference in base line before and after the phase transition is due to the difference in heat capacities of the two phases. 

Fig. 8. DSC thermograms of poly(tetrahydropyran-2,6-diyliminocarbonyl) prepared in DMSO at 19 °C fen 72 hr in 56% yield. Heating rate, 10 °C/min. A, original scanning B, rescanning after scanning up to 290 °cS8)...

Analysis of the Thermogram of Melamine Fiber in Nitrogen Atmosphere, at a Heating Rate of 10°C/min ... 

---