Temperature-modulated DSC techniques (TMDSC) are widely used in thermal analysis in industrial and university research laboratories to separate overlapping temperature-dependent and time-dependent thermal effects.
Methods used up until now have overlaid the isothermal temperature or heating ramp with a (usually) sinusoidal temperature modulation of just one frequency (single frequency method). In contrast, TOPEM® , the new advanced multi-frequency temperature-modulation technique, uses a large number of different frequencies (multi-frequency approach).
The basic idea of TOPEM® is to overlay the isothermal or ramped temperature with a time series of stochastic (random) temperature pulses of different duration.
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The advantages of TOPEM® are:
- One measurement – simultaneous measurement of sample properties as a function of time and temperature over a large frequency range
- cp determination from the pulse response – very accurate determination of the quasi-static heat capacity
- Simultaneous high sensitivity and high resolution – allows the measurement of low energy transitions and/or close-lying temperature- dependent effects
- Separation of reversing and non-reversing processes – heat capacities can be determined with unrivaled quality even if the effects overlap
- Simplifies interpretation – frequency-dependent effects (e.g. glass transitions) can be easily distinguished from frequency-independent effects (e.g. loss of moisture)
- Extended PEM technique – eliminates instrumental influences and extends the measurable frequency range
Thanks to the frequency information, effects that shift with frequency can easily be distinguished from effects that show no frequency dependence. This greatly simplifies the interpretation of results from samples that exhibit overlapping effects.
At the same time, TOPEM® allows the quasi-static frequency-independent heat capacity to be measured.