Volume–temperature relations of amorphous polymers over on extended temperature range

Glass Transitions of the Poly-(n-Alkyl Methacrylates)

“…For example, though poly-(styrene) and poly-(methyl methacrylate) have almost identical values of Tg their specific volumes in the liquid state are quite different. 23 In this instance, therefore, Tg does not vary with the liquid density, (30) F. Bueohe, J. Chem. Phy a., 24, 418 (1956).…”

Free Volume in a PVME Polymer–Water Solution

“…Next, the slope of the excess free volume in the region above T g given as α L – α G would correspond to the coefficient of thermal expansion of the excess free volume α L f determined from the free volume, calculated with the probe radii between 0.5 and 0.6 Å (Figure b). The assumption that the excess free volume in glassy region would follow the slope of the thermal expansion, α G , for any probe other than that with zero radius is hard to justify and would ignore experimental curvatures, as already pointed out by Simha and Boyer. , Similarly, in the case of pure PVME the free volume fraction at T g computed by the predictive relation derived by the Simha–Boyer theory would be (α L – α G ) T g MD = (6.78 × 10 –4 K –1 – 3.00 × 10 –4 K –1 ) × 275 K = 10.4%. This is again close to the universal value 11.3%, and it corresponds to the value obtained by the probe with radius R p = 0.5 Å …”

Transition vitreuse dans les polymères amorphes. Etude phénoménologique

“…MANDELKERN, 1956). Toutefois, ces trois estimations conduisent h des valeurs de ]s/b et de Too tr~s voisines, mais l'inter-pr6tation physique du volume libre de relaxation est diff6rente dans chaque cas.…”