Recording thermal transitions with

DSC thermograms were recorded on either a DuPont 900 or a Stanton Redcroft STA 785 + CPC 706 instrument with a heating rate of 20°C/min. TGA thermograms were determined with the Stanton Redcroft instrument. Thermal transitions were also studied using a Linkam... 

The conformation of the helical polypeptides changes from helical to nonhelical with an increase in temperature, and the glycopolypeptides and polypeptides show similar thermal transition behavior (not shown) (23). CD spectra for all other random coil and a-helical glycopolypeptides were recorded and found to be consistent with our previously reported data (23, 24) with some variations in absolute intensities, regardless of the identity of the saccharides used in the modification (Gal or Cap). These observations confirmed that the glycosylation of polypeptides with different saccharides does not significantly alter the secondary structure of the polypeptides. 

In a typical differential thermal analyzer, an inert material like alumina or metallic block and the sample holder are connected with thermocouples and kept in a furnace. Both of them are subjected to identical thermal cycles. With the help of thermocouples, the temperatures on the inert surface and the sample are recorded and the difference in temperatme between the sample and the inert material is plotted against temperature or the time. This helps to find the reactions such as endothermic or exothermic reaction. It also provides data like melting temperature, glass transition temperature, crystallization temperature, etc. The enthalpy change also can be noted by measuring the area under the DTA peak. 

Dilatometry and thermomechanical analysis (TMA) are also techniques used to monitor the thermal behavior of fibers. They both employ a sensitive probe in contact with the surface of the sample, and the thermal transitions are detected either by a change in volume or modulus of the sample, respectively. In the latter case, the probe necessarily penetrates the sample surface. A variable transformer records the voltage output that is directly proportional to the degree of displacement of the probe during a thermally induced transition. TMA is a more sensitive technique than either DTA or DSC for detecting thermal transitions. 

MHz H-NMR spectra were recorded on a Varian XL-200 spectrometer from CDCl or C D NO solutions and with TMS as internal standard. IR spectra were recorded on a Perkin-Elmer Model 1310 infrared spectrophotometer from KBr pellets. Perkin-Elmer DSC-2 and DSC-4 Differential Scanning Calorimeters were used to determine the thermal transitions. Glass transition (Tg), melting (T ), crystallization (T ), smectic-nematic >... 

Thermal transition data were recorded for blends crystallised at 40 "C pure block copolymers did not crystallise at 40° C and were crystallised at room temperature. Samples with 50 wt % or more PCL homopolymer showed single crystalline melting endotherms at 55-60 °C, depending on composition. The pure... 

In the Cp evaluation, the dispersion of the data is rather large because the thermal event is usually a very small one in terms of the energies involved (<0.5 mJ/s). It may happen that, although in the raw DSC recording the transition is detectable, the signal-to-noise ratio in the specific heat evaluation is indeed comparable with that of the transition itself ... 

Fe(ptz)6](BF4)2 (ptz = 1-propyl-tetrazole), is another model Fe coordination compound exhibiting thermal SCO with a transition temperature on warming t /2 of ca. 135 K. The Fe Mossbauer spectra of Fig. 2.16, recorded on warming from 98 K, clearly confirm the transition at this temperature between the LS phase (singlet shown in dark grey) and the HS phase (quadrupole doublet shown in grey). 

The thermal transitions were recorded with a different scanning calorimetry (DSC) Perkin-Elmer DSC-7 according to a conventional procedure. The wide-angle X-ray procedure was performed with filtered CuKa radiation using DRON-3M diffracto-... 

In differential thermal analysis with the instrument described in Figs. 4.6 and 4.7, in which the heat flow is regulated electronically, this difficulty caused by a changing base line does not arise. The DSC of Fig. 4.6 does, however, have problems if the temperature of the sample stays constant, as during a sharp melting transition. In this case the differential heater cannot correct fully for the temperature difference, and the average heater must supply part of the heat of transition in the early part of the transition, so the recorded transition peak rises more slowly. After the transition, the differential heater corrects this mistake, so that the total heat of transition is recorded, but the shape of the peak does not correspond to the actual melting process and correction procedures must be applied. ... 

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