Thermograms, DSC

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... 

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). 

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.

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)...

Fig. 1. DSC thermogram of polymers (a) polyethylene with homogeneous catalyst (b) polyethylene with embedded catalyst (c) catalyst embedded polystyrene.

Differential Scanning Calorimeter (DSC) thermograms were obtained on a Perkin Elmer DSC-2 run at 10°C per minutes. Dynamic Mechanical Thermal Analysis (DMTA) spectra were obtained on a Polymer Labs DMTA at a frequency of 1Hz with a temperature range from -150°C to +150°C at a scan rate of 5°C per minute. 

Figure 2. DSC thermogram of network H-4-40 before and after desilylation.

Fig. 6 DSC thermograms showing representative thermal transitions in frozen solutions. The top thermogram is for a mannitol solution and is characteristic of a metastable glass-forming system.

The glass transition of solutes that remain amorphous during and after the freezing process can often be seen in the DSC thermogram as a shift in the baseline toward higher heat capacity. This is illustrated in the DSC thermogram of sucrose solution in Fig. 6, in which the glass transition is observed at — 34°C. 

Figure 9. DSC thermogram of Ht-BlB-34, before and after tensile elongation to break.

The DSC thermograms of several triblock copolymers and homopolymer HB are coiq>ared to that of a low density polyethylene in Figure 2. The thermograms are those of the first run on quenched samples. Their behavior is similar except that the temperature of the maximum in the DSC melting peak, Tm, for LDPE (110 C) is higher than that of HB (102°C). The depression of the melting point brought about by the presence of 5 to 8 mole percent... 

Figure 2. Comparison of the Differential Scanning Calorimetry (DSC) thermograms of the homopolymer HB and various block copolymers to that of the LDPE. Weight of each polymer sample is indicated in the parentheses. The instrument range is 2 mcal/s for all the runs.

An X-ray diffraction study of PHA-10UND= showed that this PHA was amorphous however, the DSC thermogram of the polymer showed a small but clear endotherm at approximately 38 °C. The glass transition temperature of PHA-10UND= is approximately - 46 °C which is significantly lower than those of the poly(nHAMCL)s. Both the melting temperature and the glass transition tempe-... 

The differential scanning calorimetry (DSC) thermogram of miconazole was obtained using a DuPont 2100 thermal analyzer system. The thermogram shown in Fig. 2 was obtained at a heating rate of 10°C/min and was run over the range 50—300 °C. Miconazole was found to melt at 186.55 °C. 

The differential scanning calorimetry (DSC) thermogram of niclosamide was obtained using a General V4 IC DuPont 2100. The data points represented by the curve shown in Fig. 2 were collected from 200 to 400°C using a heating rate of 5°C/ min. It was found that the compound melted at 231.66°C with an enthalpy of fusion equal to 69.31 J/g. 

Differential scanning calorimetry can be extremely useful in the study of compound polymorphism. Suitably prepared films of 2,4-dinitrophenyl-2,4-dinitrobenzoate will exhibit phase transformations among all four polymorphs [46], as has been shown in Fig. 6. The complicated DSC thermogram contains... 

Some compounds are capable of forming solvates with a variety of solvents, and DSC can be effectively used to screen the various species that may be isolated from the different systems. Piretanide [34] provides a typical example of this behavior, for which representative DSC thermograms have been illustrated in Fig. 12. After recrystallization of this compound from 27 different solvents, six... 

Fig. 6. DSC thermogram of methyl-branched polyethylene generated by ADMET...

The DSC thermogram of bromocriptine mesilate, obtained with a Perkin Elmer DSC-2 instrument at a heating rate of 20 °C/min. and in a nitrogen atmosphere, is shown in fig. 9. 

Figure 8 shows the DSC thermogram of griseofulvin obtained with a DuPont Model 900 Thermal Analyzer. A single sharp melting endotherm occurs for this substance with onset temperature at 216 C. 

Figure 10. DSC thermogram(a) and X-ray diHracUon(b) of CgAzoQoN+Br cast film.

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