Graft copolymerization of acrylic acid onto sawdust using KMnO4 as initiator

The oxidation of sawdust (Picea abies) with potassium permanganate in diluted aqueous solution creates active sites for its copolymerization with acrylic acid in hexane. Acrylic acid copolymerized and non copolymerized sawdusts were examined in a scanning electron microscope and presented strong morphological differences. Separation and analysis by FTIR and (CP)-C-13/MAS NMR of lignin and holocellulose by respective delignification with sodium chlorite and hydrolysis of holocellulose with concentrated sulfuric acid, of modified and unmodified sawdusts, showed that lignin was more reactive to grafting than holocellulose. (CP)-C-13/MAS NMR investigations allowed to propose a suitable grafting mechanism.