The curing reaction of a thermosetting system is investigated by DSC and temperature modulated DSC (TMDSC). When the material
vitrifies during curing, the reaction becomes diffusion controlled. The phase shift signal measured by TMDSC includes direct
information on the reaction kinetics. For long periods the phase shift is approximately proportional to the partial temperature
derivative of the reaction rate. This signal is very sensitive for changes in the reaction kinetics. In the present paper
an approach to determine the diffusion control influence on the reaction kinetics from the measured phase shift is developed.
The results are compared with experimental data. Further applications of this method for other reactions are proposed.