The Attainable Superheat: From Simple to Polymeric Liquids

The phenomenon of the attainable superheat of a substance and the kinetics of nucleation of a vapor phase have been studied experimentally for liquids with molecular weight from 102 to 104. The values of the temperature of spontaneous boiling-up T* have been measured over a wide range of parameters (pressure, heating rate, CO2 coIntent, molecular weight, and thermal stability of a substance) by the method of controlled pulse heating of a thin wire probe using pulse lengths from 0.01 to 4 ms. The investigation is based on a gradual increase in the molecular weight of a sample. The peculiarities of spontaneous nucleation in polymeric liquids that do not boil without decomposition are discussed. It is shown that this phenomenon is a reproducible relaxation process in a polymeric system, which accompanies the initial stage of its thermal decomposition