Modification of lignin for the production of new compounded materials.

摘要: The cell walls of woody plants are compounded materials made by in situ polymerization a polyphenolic matrix (lignin) into web fibers (cellulose), process that is catalysed polyphenoloxidases (laccases) or peroxidases. first attempt to transform the basic strategy this natural for use human craftsmanship was ancient lacquer method. sap tree (Rhus verniciflua) contains large amounts phenol (urushiol), polysaccharide and enzyme laccase. This oil-in-water emulsion solidifies presence oxygen. Chinese began using phenomenon production highly creative artwork more than 6,000 years ago. It example an isolated being used as catalyst create artificial plastic compound. In order apply products on industrial scale, inexpensive must be used, which transferred active radicals react with different components form material. At present, following approaches have been studied: (1) lignin particle boards. Adhesive cure based oxidative phenoloxidases (laccase) radical donors. lignin-based bio-adhesive can applied under conventional pressing conditions. resulting boards meet German performance standards. By process, 80% petrochemical binders wood-composite industry replaced from renewable resources. (2) Enzymatic copolymerization alkenes. organic hydroperoxides, laccase catalyses reaction between olefins. Detailed studies acrylate monomers showed chemo-enzymatic offers possibility produce defined lignin-acrylate copolymers. system allows control molecular weights way has not possible chemical catalysts. novel enzymatically induce grafting polymeric side chains onto backbone, it enables utilization part new engineering materials. (3) activation middle-lamella wood composites. incubation oxidizing results crust fiber surface. When such pressed together, obtained standards medium-density (MDF). bound together comes close naturally grown wood. will, time, yield composites produced solely without any addition resins.