GROWTH-KINETICS OF THE (001) FACES OF HEXATRIACONTANE (C36H74) IN SOLUTION

The rate of advancement of the (001) faces of hexatriacontane crystals growing from solution in petroleum ether has been measured as a function of supersaturation at two temperatures, 13 and 22°C. A parabolic growth law is found at low supersaturation. A comparison of the activation energies calculated for the different mechanisms resulting from the BCF theory with the experimental value excludes all possibilities but one: the secondary law due to slow incorporation of growth units arrived at the steps of the growth spiral by surface diffusion. This mechanism is further supported by the value of the rate constant of the parabolic law. At high supersaturation there is a sharp increase in growth rate which is interpreted in terms of a contribution to growth from surface nucleation. The extra information thus obtained on edge energy and roughness is essential for the interpretation of the parabolic part of the growth curve. © 1979.