The glass transition temperature of partially cured polymers as a non-equilibrium parameter and its effect on observed dynamic mechanical behavior

Observations of time dependent behaviors of polymeric systems are often made with the assumption that the glass transition temperature will remain constant during the course of the experiment. This assumption may not be valid for partially cured thermosetting system, where additional cure can increase the glass transition temperature. The observed behavior can be expressed as a time derivative function of two independent variables, the experimental temperature and the state of the system. With proper assumptions, these two variables can be reduced to a single parameter (T ? T_g), whose time derivative will give terms representing the temperature and curing effect separately. Dynamic mechanical measurements have been made on partially cured systems, and the effects of the additional cure on the observed properties are observed. The seemingly complex experimental observations can be qualitatively interpreted with the change of the parameter (T ? T_g).