Cooling rate differential scanning calorimetry

DSC (differential scanning calorimetry) was performed using a Netzsch Phoenix El apparatus. Typically, samples of about 20 mg were applied in aluminium cold-sealed crucibles with heating/cooling rates of 5 °C/min. 

Another important technique is the thermal analysis technique of differential scanning calorimetry (DSC). Current high-speed DSC equipment (sometimes also referred to as hyper-DSC) allows for rapid heating (up to 500°C/min) and cooling of (small) samples and therefore an increased rate of analysis per sample... 

The preparation of immiscible polymer blends is another way to disperse a bulk polymer into fine droplets. It has been reported for several polymers that when they are dispersed in immiscible matrices into droplets with average sizes of around 1 pm, they usually exhibit multiple crystallization exotherms in a differential scanning calorimetry (DSC) cooling scan from the melt (at a specific rate, e.g., 10 Cmin ). Frensch et al. [67] coined the term fractionated crystallization to indicate the difference exhibited by the bulk polymer, which crystallizes into a single exotherm, in comparison with one dispersed in a large number of droplets, whose crystallization is fractionated temperature-wise during cooling from the melt. 

Figure 11.5 Differential scanning calorimetry scans of (a) a slowly cooled, and (b) a rapidly quenched PTT sample (heating rate, 10 °C/min)...

More advanced techniques are now available and section 4.2.1.2 described differential scanning calorimetry (DSC) and differential thermal analysis (DTA). DTA, in particular, is widely used for determination of liquidus and solidus points and an excellent case of its application is in the In-Pb system studied by Evans and Prince (1978) who used a DTA technique after Smith (1940). In this method the rate of heat transfer between specimen and furnace is maintained at a constant value and cooling curves determined during solidification. During the solidification process itself cooling rates of the order of 1.25°C min" were used. This particular paper is of great interest in that it shows a very precise determination of the liquidus, but clearly demonstrates the problems associated widi determining solidus temperatures. 

A glass transition (-75°C) and two broad bands close to 0°C are obtained b y differential scanning calorimetry performed at the cooling rate of 10°C/min from 20°C to -150°C followed by an isothermal at this temperature for 10 min and then heated to 30°C at the same rate. If the heating rate is lowered to 2 or 1 °C/min, a crystallization peak is obtained at 10°C. 

Differential scanning calorimetry (DSC). The DSC analyses were carried out using a Perkin-Elmer DSC-7 and a DuPont 910DSC. Tg was defined as the midpoint of the change in heat capacity occurring over the transition. The samples were first scanned to 95°C, thereafter cooled and recorded a second time. The Tg was determined from the second run. The measurements were carried out under an atmosphere of dry nitrogen at a heating rate of 10°C/min. 

Crystallinity was determined using differential scanning calorimetry. About 5-10 mg of an experimental agent was heated from 25 to 200°C at a heating rate of 20°C/ minute. The sample was isothermed at 200°C for 1 minute and then cooled at a cooling rate of 20°C/minute to ambient temperature. Crystallization data represents peak temperatures of exotherms in the cooling cycle and are summarized in Table 1. 

Figure 2 Differential scanning calorimetry results (cooling) for a sample of runny cream and thick cream. Run conditions sample mass 13.0 mg, cooling rate 10°C/min, sealed aluminum pans.

Differential Thermal Analysis (DTA) — A procedure for recording the difference in temp between a substance and a reference material, against either time or temp as the two specimens are subjected to identical temp regimes in an environment heated or cooled at a controlled rate. The record is the differential thermal or DTA curve the temp difference (A T) is usually plotted on the ordinate with endothermic reactions downward and time or temp on the abscissa increasing from left to right Differential Scanning Calorimetry (DSC) —... 

Glass transition temperatures were measured by differential scanning calorimetry (DSC) using a DuPont 900 Differential Thermal Analyzer. The samples were cooled to -100°C in a closed pan and then scanned to 150°C at a rate of 15°/minute. 

All reactions were carried out under an argon atmosphere. The solvents used were of commercial p.a. quality. H and 13C NMR data were obtained on a Bruker ARX 400 spectrometer. Phase transitions were studied by differential scanning calorimetry (DSC) with a Bruker Reflex II thermosystem at a scanning rate of 10 °C min-1 for both heating and cooling cycles. UV-Vis and fluorescence spectra were recorded on a Jasco V-550 spectrophotometer and a Varian-Cary Eclipse spectrometer, respectively. Low-resolution mass spectra were obtained on a Varian... 

Differential scanning calorimetry experiments were performed on a TA DSC 2920 instrument from room temperature to -150°C with a cooling rate of 1.5°C/min under N2 atmosphere. 

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