Heat pulse monitoring of curing and polymer–gas systems

An implantable thermal probe is used to study the reaction of molten polymers and curing systems to pulse heat release. At the heating rates T˙≥5·10⁵K/s, a polymer system shows the response to pulse heating that is confined in time and reproducible with respect to temperature. This response is related to the abrupt change in the conditions of the contact between the probe and a substance. The temperature of the response T^* is determined by the polymer properties and depends on the pressure and T˙. The pulse thermal probe method, which includes two measuring procedures, complementing each other, has been used to monitor a number of processes in polymeric systems. The variation of the values of T^* and the thermal activity of a polymer is compared with the variation of its molecular weight (M?_n～ 10²–10⁶), the molecular weight distribution, and the concentration of a low molecular weight component. The method allows one to trace the kinetics of polymerization and curing and the kinetics of dissolution of volatile impurity and polymer devolatilization, and to determine the limit of supersaturation of gas solutions in molten polymers. The pulse repetition frequency is changed from 0.1 to 1 Hz. The heated volume of a substance is 10^?4 mm³. © 1994 John Wiley & Sons, Inc.