Lateral growth of extended-chain single crystals of vinylidene fluoride and trifluoroethylene copolymers

Lateral growth of extended chain single crystals (ECS Cs) of vinylidene fluoride and trifluoroethylene copolymers, P(VDF/TrFE), within the mobile hexagonal phase at high temperature and at atmospheric and high pressures was investigated directly by polarized optical microscopy. The VDF molar contents (x) studied were 0.75 and 0.78, which were less than x at the triple point (x = 0.82) at atmospheric pressure. The lateral growth was steady growth. The plot of logarithmic lateral growth rate (log V) against the inverse of the degree of supercooling (ΔT-1) gave a straight line, i.e., V = V0exp(-C/ΔT), where V0 and C are constants, and does not show any breaking. These results confirmed that the lateral growth is mainly controlled by a two-dimensional nucleation process and shows only one `regime'. The number of ECS Cs increased linearly with time, which indicates homogeneous nucleation.