THERMODYNAMIC CONSIDERATIONS OF THE INSTABILITY OF ROD MORPHOLOGIES

Several unreasonable treatments in the previous derivations of the 2pi R0 criterion are indicated and discussed. A chemical potential distrib ution model involving the variational results of rod morphologies is t hus developed to reconsider the instability of an infinitely long cyli ndrical second phase via interface diffusion. It is proved that for a sinusoidal perturbation (deltaomega much-less-than 1), when lambda > 2 pi (R + delta), nonlinear distribution of the mean curvature of the cy lindrical surface against delta must be considered, while linear analy sis is only acceptable when lambda < 2pi (R + delta). Three critical w avelengths are thus derived from linear and nonlinear analyses, althou gh they could also be united into the 2piR0 criterion which works eith er for delta/R0 much-less-than 1 or not. When lambda > 2piR0, the rod certainly breaks up with the intervals lambda. The developed model app lies to arbitrary perturbations in analysing the instability of rod mo rphologies.