Equilibrium milting temperature: Some experimental data with isotactic polypropylene, polybutene‐1, and polypentene‐1

Abstract

Abstract Extrapolation of „kinetic”︁ melting temperatures of polymer samples crystallized at different temperatures should localize the „equilibrium”︁ melting temperature; however, before approaching this value, crystallization times become extremely long, and a valid criterion of extrapolation must be sought. At the moment, a linear extrapolation seems to be reasonable, at least for the attainment of first approximation results. Polypentene‐1, modification 1, appears to have an equilibrium melting temperature around 130°C.; polybutene‐1 modification 1 around 138°C., and modification 2 around 130°C. The determination for polypropylene is particularly uncertain, because of a remarkable influence of the thermal history of the crystallized samples. For this polymer the equilibrium value is surely above 182–183°C., but it is difficult to say whether it is immediately above this value or rather over 200°C.