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Modification of lignin for the production of new compounded materials

机译：木质素改性以生产新的复合材料

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摘要

The cell walls of woody plants are compounded materials made by in situ polymerization of a polyphenolic matrix (lignin) into a web of fibers (cellulose), a process that is catalysed by polyphenoloxidases (laccases) or peroxidases. The first attempt to transform the basic strategy of this natural process for use in human craftsmanship was the ancient lacquer method. The sap of the lacquer tree (Rhus verniciflua) contains large amounts of a phenol (urushiol), a polysaccharide and the enzyme laccase. This oil-in-water emulsion solidifies in the presence of oxygen. The Chinese began using this phenomenon for the production of highly creative artwork more than 6,000 years ago. It was the first example of an isolated enzyme being used as a catalyst to create an artificial plastic compound. In order to apply this process to the production of products on an industrial scale, an inexpensive phenol must be used, which is transferred by an enzyme to active radicals that react with different components to form a compounded material. At present, the following approaches have been studied: (1) In situ polymerization of lignin for the production of particle boards. Adhesive cure is based on the oxidative polymerization of lignin using phenoloxidases (laccase) as radical donors. This lignin-based bio-adhesive can be applied under conventional pressing conditions. The resulting particle boards meet German performance standards. By this process, 80% of the petrochemical binders in the wood-composite industry can be replaced by materials from renewable resources. (2) Enzymatic copolymerization of lignin and alkenes. In the presence of organic hydroperoxides, laccase catalyses the reaction between lignin and olefins. Detailed studies on the reaction between lignin and acrylate monomers showed that chemo-enzymatic copolymerization offers the possibility to produce defined lignin-acrylate copolymers. The system allows control of the molecular weights of the products in a way that has not been possible with chemical catalysts. This is a novel attempt to enzymatically induce grafting of polymeric side chains onto the lignin backbone, and it enables the utilization of lignin as part of new engineering materials. (3) Enzymatic activation of the middle-lamella lignin of wood fibers for the production of wood composites. The incubation of wood fibers with a phenol oxidizing enzyme results in oxidative activation of the lignin crust on the fiber surface. When such fibers are pressed together, boards are obtained which meet the German standards for medium-density fiber boards (MDF). The fibers are bound together in a way that comes close to that by which wood fibers are bound together in naturally grown wood. This process will, for the first time, yield wood composites that are produced solely from naturally grown products without any addition of resins.
机译：木本植物的细胞壁是通过将多酚基质（木质素）原位聚合成纤维网（纤维素）制成的复合材料，该过程由多酚氧化酶（漆酶）或过氧化物酶催化。改变这种自然过程用于人类工艺的基本策略的第一个尝试是古老的上漆方法。漆树（Rhus verniciflua）的汁液含有大量的苯酚（urushiol），多糖和酶漆酶。该水包油乳液在氧气存在下固化。六千多年前，中国人开始将这种现象用于生产极富创意的艺术品。这是将分离的酶用作制备人造塑料化合物的催化剂的第一个例子。为了将该方法应用于工业规模的产品生产，必须使用廉价的苯酚，苯酚通过酶转移到与不同组分反应形成复合材料的活性自由基上。目前，已经研究了以下方法：（1）木质素的原位聚合用于生产刨花板。胶粘剂固化基于木质素的氧化聚合，使用酚氧化酶（漆酶）作为自由基供体。这种基于木质素的生物粘合剂可以在常规压制条件下使用。所得刨花板符合德国性能标准。通过此过程，木材复合工业中80％的石化粘合剂可以用可再生资源中的材料代替。 （2）木质素和烯烃的酶促共聚。在有机氢过氧化物的存在下，漆酶催化木质素和烯烃之间的反应。对木质素和丙烯酸酯单体之间反应的详细研究表明，化学-酶促共聚提供了生产确定的木质素-丙烯酸酯共聚物的可能性。该系统允许以化学催化剂无法控制的方式控制产物的分子量。这是一种新的尝试，以酶促方式将聚合物侧链接枝到木质素主链上，并且使木质素能够用作新的工程材料的一部分。 （3）木纤维中间层木质素的酶促活化，用于生产木质复合材料。木纤维与苯酚氧化酶的孵育导致木质素外壳在纤维表面的氧化活化。当将这些纤维压在一起时，获得的板符合德国中密度纤维板（MDF）的标准。纤维的粘合方式与自然生长的木材中将木质纤维粘合在一起的方式相近。该工艺将首次获得仅由天然生长产品生产而无需添加任何树脂的木材复合材料。

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  • 来源
    《Applied Microbiology and Biotechnology》 |2001年第4期|387-394|共8页
  • 作者

    A. Hüttermann; C. Mai; A. Kharazipour;

  • 作者单位

    Abteilung für Technische Mykologie Institut für Forstbotanik der Universität Göttingen Büsgenweg 2 37077 Göttingen Germany;

    Abteilung für Technische Mykologie Institut für Forstbotanik der Universität Göttingen Büsgenweg 2 37077 Göttingen Germany;

    Pfleiderer AG 59759 Arnsberg Germany;

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