Reflection spectrum Thermal expansion

The dynamic mechanical spectrum of a PAN fiber obtained by Minami [205] is shown in Figure 12.20. The real modulus at room temperature is approximately 4 x 10 MPa. The modulus begins to decrease near 75°C and drops to 2 x 10 MPa, which is a decrease of slightly over one order of magnitude, and corresponds to the onset of the glass transition. The Tg based on the midpoint of the decrease in real modulus is approximately 115°C. This is higher than the values obtained using thermal expansion coefficient (85°C) or DSC (100°C), and simply reflects the temperature shift characteristic of dynamic techniques mentioned earlier. 

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