ΩCpT_g and related quantities for high polymers

Abstract

Abstract The quantity ΩCpTg for 30 different polymers averages 27.5 cal g−1 but is given more accurately by ΩCpTg = 15 + 4 × 10−2 Tg. There is a good linear correlation between ΩCp and the difference, Ωβ, in thermal expansion, dV/dT, above and below Tg. This correlation can be explained empirically since both ΩCp and Ωβ are inversely proportional to Tg. It can also be explained by the fact that Tg is directly proportional to the energy of hole formation eh. We show that the coefficient of expansion in the liquid state a t varies inversely with eh. We finally note the similarity of hole volumes vh as calculated from hole theory and the free volume quantity ΩαTg from Simha and Boyer. The various intercomparisons given in this paper between specific heat and thermal expansion quantities allow one to assess conflicting literature data in either of these disciplines.