Specific heat capacity scanning method

ASTM E1269, 2004. Standard test method for determining specific heat capacity by differential scanning calorimetry. 

The temperature dependence of the specific heat capacity was discussed in Chapter 4 and illustrated schematically in Figure 4.1. This dependence enables the measurement of Tg by differential scanning calorimetry (by far the most commonly used method to measure it). 

It is seen that the calibration constant disappears, which assumes that it is constant over the experimental conditions. The calculation is carried out using dedicated software. In some circumstances the crucible used for the sample may have to be different from that used for the calibrant. This means that a correction will be required to take into account the difference between the heat capacity of the two crucibles - readily calculated with sufficient accuracy. Measurements can be made at a series of temperatures but are meaningful only within the quasi-steady-state region of the experiment. The specific heat capacity of sapphire has been listed by ASTM in connection with the standard test method E 1269 (1999) for determining specific heat capacity by differential scanning calorimetry. 

E 1269 (1999) Test method for determining specific heat capacity by differential scanning calorimetry E 1354 (1994) Test method for heat and visible smoke release rates for materials and products using an oxygen consumption calorimeter... 

The thermal conductivity was measured by a laser flash method. Disk-type samples (12.7 mm in diameter and 1mm in thickness) were set in an electric furnace. Specific heat capacities were measured with a differential scanning calorimeter. Thermal diffusivity (X, Wm K ) was calculated from thermal diffusivity (a, m s ), density (p, g/cm ) and specific heat capacity (C, J g K ) at each temperature using the following ... 

The glass transition point is typically not sharp and may take place over a range of more than 10 C. You should think of the glass transition more as a change in physical properties (specific heat capacity, volume) than a thermodynamic phase transition. 7 can be determined by two main methods Differential scanning calorimetry (see Chapter 2 for more... 

Temperature-modulated differential scanning calorimetry (T-MDSC) applies a thermal modulation in temperature to a conventional DSC mn and determines a dynamic heat capacity from the relationship between the modulation components of temperature and of heat flow. Primary application of this technique has been the measurement of specific heat capacity and the examination of the anomaly in a relaxation process such as alpha process related to the glass transition. An application to the first-order phase transitions of crystallisation and melting of polymer crystals has recently been suggested. The method and typical results are described. 13 refs. 

Any polymer property that changes with temperature and has different values above and below Tg can be used, in principle, to determine Tg. For example, the change in specific volume, heat capacity, or elastic modulus may be used to measure Tg. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) are two common methods for such determinations. An example of the results of DSC analysis Is presented In Fig. 3.46. It is common for different methods to yield slightly different values for Tg. 

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