HEAT PULSE MONITORING OF CURING AND POLYMER GAS SYSTEMS

An implantable thermal probe is used to study the reaction of molten p olymers and curing systems to pulse heat release. At the heating rates T greater than or equal to 5 . 10(5) K/s, a polymer system shows the response to pulse heating that is confined in time and reproducible wi th respect to temperature. This response is related to the abrupt chan ge in the conditions of the contact between the probe and a substance. The temperature of the response T is determined by the polymer prope rties and depends on the pressure and T. The pulse thermal probe metho d, which includes two measuring procedures, complementing each other, has been used to monitor a number of processes in polymeric systems. T he variation of the values of T and the thermal activity of a polymer is compared with the variation of its molecular weight (($) over bar M(n) similar to 10(2)-10(6)), the molecular weight distribution, and t he concentration of a low molecular weight component. The method allow s one to trace the kinetics of polymerization and curing and the kinet ics of dissolution of volatile impurity and polymer devolatilization, and to determine the limit of supersaturation of gas solutions in molt en polymers. The pulse repetition frequency is changed from 0.1 to 1 H z. The heated volume of a substance is 10(-4) mm(3). (C) 1994 John Wil ey and Sons, Inc.