Hello all,
I would like to get a curing kinetics of a resin at a certain temperature. I have seen many papers, but what I fail to understand is, if the measurement is a single shot (i.e. single measurement) or for each temporal (time) point, do I have to do one measurement (I know the 100% curing reaction that has to be done for reference).
If the answer is yes (i.e. a single shot measurmeent), what do i actually measure as a function of time (simply heat flow?).
Thanks for helping.
Best regards
Santhosh
Yes, the measured signal is heat flow (W). In an ideal case, isothermal DSC baseline is a completely flat line. Thus, its deviation/curvature is only caused by heat evolution during the curing process. If you integrate the isothermal heat flow signal and normalize it to the heat of 100% curing, you would obtain "curing degree vs. time" curve at certain temperature.
Care should be taken when choosing the temperature and initial heating ramp - at high temperatures the curing can occur during the initial heating ramp - quite fast heating rates are recommended. The curing peak can also partially overlap with signal transient (heating ramp -> isotherm).
If the temperature is too low, the curing is very slow and the heat flow signal can be lost in noise and long-term baseline drift.
To be as precise as possible, the integration of heat evolution during curing arises only from the molecular process of curing. As Tibor said, "curing peak can overlap with signal transient." This is in part because the uncertainty of this measurement always includes 1) when does curing begin, and 2) when does curing stop. Can get close, except without knowing 1) and 2) with a high degree of precision, progressively more difficult to get closer and closer to the "right" answer.
Thanks to Tibor, Eman and Walter all of your answers. Most useful.
Best regards
Santhosh
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