Abstract
Photo-oxidation of poly vinyl alcohol was studied under ultraviolet rays, and the amounts of carbonyl formation (aldehydic, acidic, ketonic and esteric type) were measured by IR method. Furthermore, the mechanism of photo-oxidation was estimated and the kinetics were investigated by the steady-state method.
The results revealed that the rate of each carbonyl formation can be expressed by the equation, vc=o=B{1-exp(-At)} (A, B: const.). It can be seen from relationships between the changes of carbonyl formation ratio and the radiation time that the mechanism is content with the above equation, and thus the estimated mechanism of photo-oxidation is appropriate.
Furthermore, the behavior of carbonyl formation was discussed on the basis of kinetic parameter (A), activation energy (Ea) and entropy of activation (ΔS≠). It is considered that the formations of aldehydic and acidic types contribute to the photo-oxidation of poly vinyl alcohol, while that of ketonic type depends on the decomposition of aldehydic type.
