This paper studies the phenomenon of spontaneous boiling-up of polymeric li
quids on heating at rates ((T) over dot) up to 10(7) K . s(-1). A model of
the thermal equation of state for (polymer + monomer) systems and a procedu
re for determination of the spontaneous boiling-up temperature T* for polym
eric liquids. taking decomposition into account, are proposed, The experime
ntal data on T*((T) over dot) for a number of polymer melts are compared wi
th results calculated from the model.