PEI, Glass Transition by ADSC

Sample

Polyetherimide, PEI, Ultem 1000, injection-molded part

Conditions 

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

Evaluation 

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 c_p temperature function and cp is shown in tabular form: 

Conclusions

As the example demonstrates, ADSC separates so-called "reversing" and "non-reversing" effects. This can be very useful with reactions that overlap. In general, c_p 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}