Crystal nucleation and the crystalmelt interfacial tension in linear hydrocarbons

Abstract

Recent results on the homogeneous nucleation of crystals in n‐alkane (CnH2n+2) melts are used in conjunction with simple nucleation theory to calculate scaled crystal‐melt interfacial tensions, α (n), per CH2 group. α(n) falls off smoothly and, at first, sharply with n increasing to 12–15, where it levels and remains roughly constant at ca. 0.15 to n = 32, at least. We show that these results are accounted for satisfactorily by the Spaepen‐Meyer negentropic model for the crystal‐melt tension, if it is assumed that there is high probability for the occurrence, within the melt, of planar conformations persisting for 14–15 C atoms.

Crystallization from the Amorphous State: Nucleation–Growth Decoupling, Polymorphism Interplay, and the Role of Interfaces

“…The result is a weak value of the scaled interfacial tension. It is the situation considered in the negentropic model of Spaepen 30,34 (see Fig. 12).…”

Isotactic poly(butene‐1) trigonal crystal growth in the melt

“…Liquid atoms at the crystal–liquid interface cannot adopt as many configurations as in the bulk because of the special boundary conditions of the crystal plane. This concept was introduced into the systems of n ‐alkanes as the negentropic model by Turnbull and Spaepen 38. They found that scaled crystal‐melt interfacial tensions fall off asymptotically to a constant value with increasing chain length; they explained this by the segmental nature of n ‐alkane chains.…”

Carbon dioxide-induced melting point depression of biodegradable semicrystalline polymers

“…The CO 2 molar density at the experimentally observed kink point for octacosane is 5910 mol/m 3 ; for C28 with ethane it is 6620 mol/m 3 , and for C28 with ethylene it is 4030 mol/m 3 . These values are comparable to the molar density of a Kuhn monomer unit of a pure octacosane melt, 8500 mol/m 3 [30]. Hence, we adopt the Kuhn monomer unit as the molar volume unit, u, for describing the behavior of polymers.…”