REACTION ORDERS OF DECOMPOSITION OF ANHYDROUS AMORPHATES

Solids can occur either as crystalline or as (particulate) amorphates. The chemical stability of the solid in crystalline form will differ from the same entity in amorphous form. The amorphous form, furthermore, may be above or below a glass transition temperature, T(g) (glassy below and rubbery above T(g)), and it is shown in the following that a simple rubbery amorphate should decompose by first order and the rate constants should adhere to an Arrhenius relationship with an activation energy which is the difference between ground state and excited state energies. Indomethacin has been used as a model compound.