A molten polymer may crystallize by a process of chain folding to form crystalline regions in which the the molecular chains are parallel and periodically arranged. Because of the different molecular structures at the crystal-melt interfaces, the interfacial free energy per unit area of interface is anisotropic. Assume that the polymer crystallizes as a circular cylinder, (having a radius of R and a height L). The interfacial energies are E for the flat bases and S for the cylindrical sides. Assuming that the polymer nucleates homogeneously at 373o K calculate the dimensions of the critical nucleus, and the critical free energy change G.

Data:

E = 124 mJ/m2

S = 18 mJ/m2

GV = -5.2 (107) J/m3

k = 1.38 (1023) J/K