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 fi bres (cellulose) catalysed by polyphenoloxidases (laccases) or peroxid ases. The transfer of this construction strategy to the actual product ion 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 develo ped to find conditions under which lignin becomes so active that the r eaction may be feasible for technical purposes. Thus, the following in dustrial processes for the production of compounded materials are now available: (1) wood composites either by the addition of adhesives com posed of lignin and phenoloxidases or activation of the wood fibres by these enzymes; (2) compound materials made from lignin and carbohydra tes; (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 right s reserved.