Overview - ISO 19935-2:2020 (Plastics, temperature modulated DSC)
ISO 19935-2:2020 specifies a standardized method for measuring specific heat capacity (cp) of plastics using temperature modulated differential scanning calorimetry (TM-DSC). The document describes measurement principles, apparatus requirements, calibration steps and calculation procedures so that cp data are suitable for data sheets, databases, research, quality assurance and routine material checks.
Key topics and technical requirements
- Measurement principle: cp is determined from the amplitude of the modulated heat flow signal; measurement can be done during scanning or in quasi‑isothermal (step scan) modes.
- Calculation: the standard gives a formula for cp in terms of the amplitude of the periodic heat flow (ΦA), modulation amplitude of sample temperature (TA), specimen mass (m), angular frequency (ω) and a calibration constant K(ω). Units and conditions are specified to produce cp in J·g⁻¹·K⁻¹.
- Step scan option: a step integration method is provided to obtain cp by integrating heat flow over one modulation cycle when appropriate.
- Apparatus & temperature control: TM‑DSC must be capable of periodic, stepwise or pulse temperature modulation with amplitude typically in the range ±0.1 to 2.0 K and frequencies down to about 10 mHz, superimposed on an underlying scanning rate typically