| Abstract: | Photochemical and thermal geometrical isomerizations of monoazo compounds have been studied in polystyrene–n-butylbenzene compositions. Cis–trans isomer ratios established by light absorption were found to depend on matrix viscosity. Where the compositions were above their respective glass temperatures, all thermal isomerizations conformed to first-order kinetics. Where compositions were below their respective glass temperatures, the initial isomerization rates were abnormally fast, decaying to normal first-order processes after substantial amounts of reaction had taken place. These effects have been interpreted in terms of the vitreous properties of polystyrene. |
