Radical initiated oxidative degradation of oat-spelts xylan

The oxidative degradation of oat-spelts xylan (OSX) initiated by peroxydisulfate in contact with atmospheric air was investigated. The polymer degradation was assessed through the estimation of the molecular mass of the reaction mixture by size exclusion chromatography. The influence of initial OSX concentration, initiator concentration and reaction time were investigated. The results show a significant molecular mass decrease at high initiator concentration or low xylan concentration. The molecular mass decrease and the sugar analysis results indicate that the radical attack is at the glycosidic linkage. These results can be explained by a depolymerization reaction associated to the oxidative degradation. After an initiation step, the degradation is dominated by the depolymerization reaction, followed by a competition between depolymerization and recombination reactions. The recombination reaction can lead to a small increase of the molecular mass.