Solid state oxidation of polyvinyl alcohol by hydrogen peroxide-Cu (II)

A solid state oxidation of polyvinyl alcohol (PVA) was conducted with hydrogen peroxide (H2O2) and copper sulfate (CuSO4) redox system. For the reaction the PVA powder was swelled by spraying with the redox solution, and then oxidized at controlled temperature 70 °C and pH value 2-7 for 30-240 min. The structure and performance of the PVA before and after the oxidation were investigated by using FTIR-ATR, gel permeation chromatography (GPC), XRD, and 13C NMR, 1H NMR, together with chemical analysis, tensile property and surface tension measurements. The results showed that the solid state oxidation of PVA by peroxide-Cu (II) redox system was almost completed within 120 min. The reaction led to an increase in contents of carbonyl and carboxyl groups and a decrease in molecular weight for the oxidized PVA, and a good oxidation effect was observed as pH value of the reaction medium was 5. The solid state oxidation presented a new way to prepare granular oxidized PVA economically and effectively.