Polyphenoles for compounded materials

The cell walls of woody plants are compounded materials made by an in-situ polymerisation of a polyphenolic matrix (lignin) into a web of fibres (cellulose) catalysed by polyphenoloxidases (laccases) or peroxidases. The transfer of this construction strategy to the actual production of compounded materials required the adaptation of a process that takes weeks in nature to technical conditions in which reaction times of only a few minutes are allowed. Several strategies have been developed to find conditions under which lignin becomes so active that the reaction may be feasible for technical purposes. Thus, the following industrial processes for the production of compounded materials are now available: (1) wood composites either by the addition of adhesives composed of lignin and phenoloxidases or activation of the wood fibres by these enzymes; (2) compound materials made from lignin and carbohydrates; (3) duroplasts from lignin and other monomers. The main advantage of all these substances is that they are totally compatible with the terrestrial carbon cycle. (C) 1998 Elsevier Science Limited. All rights reserved.