Using wood in extruding profiles is not new, but wood fibers developed from a filler to being the main material, opening new possibilities and allowing new properties of the finished product. Compounds with 70% to 90% wood fibers can be extruded. Wood fibers are now the primary constituent in the material, and plastics are only added to ensure adequate processability. This new technology have succeeded with using conical twin screw extruder/development of spacial screw type for wood extrusion/development of special tooling for wood extrusion. These wood fiber products offer decisive advantages for new materials and are capable of tapping segments which in the past were covered exclusively by conventional materials such as solid wood or MDF boards. Also, this technology is paid attention for recycling technologies in Japan. The market for such products might increase for social demmands. And extrusion with other natural fiber materials is possible.

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Lignin-based materials, ligno-p-cresol and ligno-2,4-dimethylphenol were synthesized directly from native lignins through the phase-separation system composed of phenols (p-cresol or 2,4-dimethylphenol) and 72% sulfuric acid. Under alkaline conditions, C1-p-cresol and 2,4- dimethylphenol units nucleophilically attacked adjacent C2, followed by the cleavage of aryl ether linkages to give similar fragments, indicating that both lignophenols had the same switching function. The ligno-p-cresol was highly hydroxymethylated (HM) on the cresolic nucleus to givenetwork-type growing pre-polymers. On the other hand, the ligno-2,4-dimethylphenol hadreactive sites in only terminal units to give linear-type growing pre-polymers. The degree of network-or linear-type polymerization could be controlled by themixing of these pre-polymers. The resulting polymer chains were cleaved at the switching points (1,1-bis(aryl)propane2-O-aryl ether units) under alkaline conditions, leading low molecular weight subunits (switching function). Recyclable lignocellulosic composites were prepared by the combination of cellulose and HM lignophenol. The water resistance of composites got greatly higher with increasing ratio of HM-ligno-p-cresol to HM-ligno-2,4-dimethylphenol. Under alkaline conditions, the composites were re-separated into low molecula rweight lignophenol and cellulosemoieties. The controlled mixing ratio of HM-ligno-p-cresol and HM-ligno-2,4-dimethylphenol leads to the accurate control of mechanical and recycling propertie sof the composites.

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Lignocellulose such as wood meal and cellulose is liquefied by using polyhydric alcohols such as an average molecular weight 400 of polyethyleneglycol (PEG400) in the presence of an acid catalyst. In the case of wood liquefaction using PEG400, a condensed residue is produced when the liquefaction is prolonged. This kind of condensed residue is also produced through cellulose liquefaction in the same reaction conditions as that of wood liquefaction. These results indicate that the liquefied cellulose itself can produce condensed residue even in the absence of condensable lignin during wood liquefaction. This condensation is avoided by using the mixed liquefying reagent of PEG/glycerin. The condensed residue of the cellulose liquefaction has quite a similar IR spectrum to that produced through the model liquefaction using 5-hydroxymethylfurfural (HMF). These findings suggest that the mechanism of cellulose degradation and its condensation have the following sequence. First, cellulose is degraded and produces glucosides. Then the glucosides are decomposed to HMF derivatives as intermediates. The HMF derivatives are further decomposed to produce levulinates with releasing formates. On the other hand, the HMF derivatives are decomposed to produce a polymer that composes the condensed residue.

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