DSC heating rate

Fig. 3.9 (a) DSC trace of as-received, undoped LiAlH (97% purity) and (b) the same hydride after milling in the magneto mill Uni-BaU-Mill 5 under HES57 mode (two magnets at 5 and 7 o clock positions) for 20 h in argon. DSC heating rate 10°C/min at argon flow 50 ml/min... 

This instrument was designed to yield information intermediate between the ARC and the DSC. A sample of 0.2-0.5 g is loaded into a tube-like container and placed into the device (larger sample sizes may be used at slower scan rates). A thermocouple is connected to the outside of the tube and the cell is fitted with a pressure transducer. A similar, empty cell in the same oven with thermocouple serves as a thermal reference. The oven is heated at a slow, linear rate (0.5 to 1 °C/min), and the pressure and differential thermal data are collected. The data are presented in a fashion similar to DSC - Heat Rate (mW) vs. Temperature (°C). The thermal data are enthalpically calibrated by means of a series of standards (cahbration at high heat rates may be non-linear). Detection of thermal events approaches the sensitivity of the ARC. 

The variation of apparent T with DSC heating rate has generally been attributed to the thermal lag of the sample, which increases in step with the heating rate (20-221. This thermal lag is composed of a machine path error and a sample error which are dependent on the characteristics of the instrument and the sample, respectively (211. However, T itself is a rate dependent parameter, and a dependence on scan rate involving a relaxation activation energy is to be anticipated over and above any thermal lag errors. 

Figure 1. DSC (heating rate, 20°C/min) of PH BA, 60%, JC-labcllcd at the carboxyl position, showing the large endotherm between 340-350°C.

Fig. 5.59 Glass transition temperature of a savoury flavour powder and of ingredients used for formulating savoury flavours (measured by differential scanning calorimetry DSC heating rate 5 °C/min, second scan)...

DSC ts widely used to predict the potential explosive hazard of materials in an ASTM method. The basis of the method, developed by Committee E 27, is the determination of the reaction kinetics using Ozawa s procedure (206). Ozawa employs a ploi of the logarithm of the DSC heating rate versus the peak maxima temperatures E. Z, k. and t can be calculated from this plot. The ASTM method has been used to evaluate the thermal stability of irinitrotoluene (207). nitrocellulose (208). and many other substances. 

Figure 12.3 Effect of DSC heating rate on the value of Tg of NIST 711 samples...

Glass transition temperature K DSC, heating rate at 20°Cmin 503-563... 

Figure 4.45. Apparent heat capaeity in the melting range of 0.936 mg of -pentaeontane by standard DSC (heating rate 10 K min ) and quasi-isothermal MTDSC A = 0.05 K, / = 60 s...

Shimadzu TA-50WS DSC heating rate 20 "C min sample mass 5.00 0.003 mg. 

Perkin-Elmer IB DSC heating rate 8°C min sample mass 5 mg sealed-type aluminum sample vessel. 

Perkin-Elmer 2C DSC heating rate 10°Cmin" sample mass 4-5 mg. 

Figure 9.5 Measured heat flow rate function of a PE sample the given heat is the melting peak area (power-compensated DSC heating rate lOKmin " ).

Figure 9.6 Measured heat flow rate function for a PET sample (solid) and an empty crucible (dotted) with a power-compensated DSC (heating rate lOKmin ).

Figure 9.7 The measured functions from Figure 9.6 shifted and tilted for zero heat flow rate in isothermal equilibrium (power-compensated DSC heating rate lOKmin ).

Determined by Rheovibron, temperature of E" maximum. Determined by DSC, heat rate at 20 C/min. 

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