FTIR characterization of tropical wood-polymer composites

Abstract

Wood-polymer composites (WPC) of Geronggang (Cratoxylon arborescens), a light tropical hardwood, impregnated with methyl methacrylate (MMA), methyl methacrylate-co-acrylonitrile (1:1; MAN), and styrene-co-acrylonitrile (3:2; STAN), were prepared by in situ polymerization using gamma radiation or the catalyst-heat treatment. The FTIR spectra of the three types of WPC, with polymer loadings ranging from 10 to 70%, were compared with that of the wood itself and the respective polymers. Characteristic peaks du to C=O vibration of MMA, ≡N stretching of acrylonitrile, and ring stretching and bending of styrene monomers, were prominent in the samples that had higher polymer loadings. For the copolymeric systems, quantitation of the FTIR spectra of these characteristic peaks enabled calculations of incorporated acrylonitrile and styrene monomers in the composites to be made. The FTIR spectra of the residues remaining, after exhaustive extraction to remove homopolymer, showed that graft copolymerization of wood components with acrylonitrile and styrene monomers was possible, but not with MMA. Composites prepared by the two methods, gamma radiation and the catalyst-heat treatment, were shown to be chemically very similar.