Polymorphic Transformation of PbO by Isothermal Wet Ball-Milling

Mechanochemical polymorphic transformation of massicot to litharge was achieved by isothermal wet ball-milling. A first-order relation was observed between the fractional conversion and the milling time; the apparent activation energies for various milling conditions were obtained by kinetic treatments. The fact that the Arrhenius equation can be applied to the mechanochemical transformation suggests that the reaction cannot be explained by a simple local heating mechanism and that a mechanical effect has a fundamental role. The effects of the number, volume, and density of the milling balls on the rate constant agreed fairly well with those predicted by Matsui's equations for impact comminution in ball-milling, indicating that the action of the milling balls may be similar to that in impact comminution of granular materials.