Surface activation of wood for graft polymerisation

An investigation of graft polymerisation of wood surfaces chemically modifi ed with propionic, crotonic, or methacrylic anhydride has been undertaken. All samples exhibited weight gains when reacted with styrene in the presenc e of a free-radical initiator. However, solid-state NMR and FTIR evidence s howed that there was only grafting of monomer in the case of methacrylic an hydride modified wood. With the other two modifications, it is clear that t he styrene is in intimate contact with the wood, but that there is no chemi cal bond. Wood flour modified with crotonic anhydride followed by styrene g rafting was heated with aqueous NaOH. Following such treatment, it was obse rved that the ester bond was readily hydrolysed. However, with methacrylic modified and styrene grafted samples, the ester bond was resistant to hydro lysis. Lap joints were formed by hot pressing veneers of modified wood with monomer (styrene or methyl methacrylate) plus initiator at the interface. Extremely strong bonds were found in the case of methacrylic anhydride modi fied samples. (C) 2000 Elsevier Science Ltd. All rights reserved.