Pv. Skripov et Se. Puchinskis, SPONTANEOUS BOILING UP AS A SPECIFIC RELAXATION PROCESS IN POLYMER-SOLVENT SYSTEMS, Journal of applied polymer science, 59(11), 1996, pp. 1659-1665
The phenomenon of spontaneous bubble nucleation in extremely supersatu
rated (superheated) polymer-solvent systems has been studied experimen
tally. Spontaneous boiling-up temperatures T for polystyrene and poly
(ethylene glycol) solutions in a number of solvents have been measured
at different values of pressure p and weight fraction of polymer c by
the pulse heating method. The heating rate T varied from 10(5) to 10(
7) K/s. For all systems studied, the values of T have been found to i
ncrease with increasing p and c. The T(p, c) dependence is discussed
with the use of the data on the degree of compatibility of components.
The peculiarities of polymeric solutions manifest themselves in the r
egion c --> 1, as follows: (i) an abrupt increase (by 1-2 orders of ma
gnitude) in the slope of the T(c) dependence, and (ii) the appearance
of the dependence of T values on the heating rate. Our approach to t
he interpretation of this result assumes a change in the initial compo
sition of a solution in the course of heating due to polymer decomposi
tion. An example of the extended phase diagram of a polymer-solvent sy
stem including the kinetic surface of T(p, c) is given. (C) 1996 John
Wiley & Sons, Inc.