Optimization of radiolytic degradation of poly(vinyl alcohol)

Ionizing radiation-induced degradation of poly(vinyl alcohol) (PVA) in aqueous solutions was investigated. Experimental results demonstrate that PVA degradation was initiated by attack of (OH)-O-center dot and H-center dot, followed by random chain scission and formation of ketones, enols, aldehydes, acids, etc. Complete mineralization of PVA could be achieved providing that a sufficient radiation dose was supplied. The collaborative effects of initial PVA concentration, pH of the solution, and H2O2 dosage with irradiation dose rate on PVA degradation efficiency were evaluated by using a response surface methodology. Lower initial PVA concentrations, higher dose rates, and acidic or alkaline conditions were found to be favorable for PVA degradation. At a certain dose rate, there was an optimal H2O2 dosage to facilitate the PVA degradation. In addition, the presence Of 02 was beneficial for PVA degradation. Tentative interpretation and theoretical analysis on these effects are presented.