Making use of available data from the literature, a master correlation
based upon a two-domain-Tait representation is developed which descri
bes the asymptotic high-temperature and low-temperature PVT behavior o
f isotactic polypropylene. The transition between these two asymptotes
in the cooling mode is then handled based upon the quiescent-crystall
ization-kinetics equation of Nakamura, employing model constants for t
he temperature- and pressure-dependent crystallization rate based upon
earlier work by the present investigator. As a further step, it is sh
own that a rule-of-mixtures approach can describe the low-temperature
and high-temperature asymptotic PVT behavior equally as well as the 2-
domain-Tait model while requiring two less free parameters. In turn, s
ince the rule-of-mixtures representation contains the absolute crystal
linity as an explicit parameter, it is proposed that this model might
also be used under flow-induced conditions once the corresponding crys
tallization kinetics become established.