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In a recent paper we have shown that the ceiling temperature observed in the formation of polysulphones from liquid mixtures of sulphur dioxide and olefines, is due to the reversal of the propagation reaction. The ceiling temperature Tx obtained by extrapolation of the rate-temperature or molecular-weight temperature curves, is the temperature at which the free energy of formation of the polymer from reactants, under the given conditions specified by the subscript x, is zero. Hence

Tx = ΔHx/ΔSx

where ΔHx and ΔSx are the increments at Tx of the heat content and entropy per mole of monomer polymerized. It can easily be demonstrated that, provided the chains are long, these increments also apply to the changes in heat content and entropy associated with the propagation reaction.

Dainton, F.; Ivin, J. (1950): . In: Faraday Trans.. 331 ,