Polyetherimide, PEI, Ultem 1000, injection-molded part
Measuring cell: DSC821e with sample changer and cryostat cooling
Pan: Aluminum standard 40 µl
Sample preparation: 17.546 mg cut with knife so that the bottom is flat
DSC measurement: Heating from 200 to 229 at a mean rate of 1 K/min. Amplitude of sinusoidal oscillation 1 K, period 1 min
Atmosphere: Nitrogen, 50 cm3/min
The evaluation of the ADSC curves is based on fast Fourier analysis (FFT). In addition to the curves displayed, curves of the real and imaginary components of the specific heat capacity could also be shown.
Each calculated curve can be numerically evaluated, e.g. the non-reversing peak integrated to get the enthalpy change of the relaxation peak. The glass transition is evaluated from the cp temperature function and cp is shown in tabular form:
As the example demonstrates, ADSC separates so-called "reversing" and "non-reversing" effects. This can be very useful with reactions that overlap. In general, cp changes are reversing effects, e.g. at the glass transition. Non-reversing effects are enthalpy relaxation, cold crystallization and all kinds of chemical reactions.
PEI, Glass Transition by ADSC | Thermal Analysis Handbook No.HB245 | Application published in METTLER TOLEDO TA Application Handbook Thermoplastics