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 f rom the same entity in amorphous form. The amorphous form, furthermore , may be above or below a glass transition temperature, T(g) (glassy b elow 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 activatio n energy which is the difference between ground state and excited stat e energies. Indomethacin has been used as a model compound.