Application of Liquefaction to Wood-Based Materials Hard to be Abandoned

以聚乙二醇/甘油混合物为溶剂，硫酸为催化剂，对日本柳杉的液化进行了研究。结果表明，液化木中的木材含量可提高近50%。液化后的木材与各种环氧化合物反应，形成一种新的树脂体系。通过改变液化木材与环氧树脂的比例来评价固化树脂的粘弹性能。固化后的树脂在40-70℃范围内一般呈现一个宽广的玻璃化转变，表明形成了互穿聚合物网络。作为一种难废弃的木质材料，我们用同样的方法研究了几种含聚苯乙烯和聚甲基丙烯酸甲酯的木质聚合物复合材料的液化行为。然而，由于浸渍到木材中的聚合物会阻碍溶剂与木材之间的亲和力，这些液化过程并不顺利。以米粉、稻草、一枝黄花的茎和不同树种(兴安落叶松、锯齿叶和银杏)的叶片为原料，在相同的溶剂和催化剂下进行了液化研究。结果表明，稻草和树叶具有较好的抗液化能力。另一方面，米粉和一枝黄花的茎很容易液化。碱处理改善了稻草的液化性能。从一枝黄花的米粉和茎中获得的产品也被证明通过与各种环氧化合物反应来提供树脂。这些固化树脂在测量粘弹性能的温度依赖性方面表现出与木材树脂几乎相同的行为。

The Liquefaction of Sugi (Cryptomeria Japonica) was investigated by using polyethylene glycol/glycerol mixture as solvent and sulfuric acid as catalyst. As the results, the wood content in liquefied wood was increased up to appioximately 50%. The liquefied wood was reacted with various epoxy compounds to develop a new resin system. The viscoelastic properties of cured resins were evaluated by the changing the ration of liquefied wood to epoxv compound. The cured resins generally displayed one broad glass transition at 40-70℃, that suggested to form interpenetrating polymer networks. Further, their normal adhesive shear strength was recognized to be the same as commercial epoxy resins.As the wood-based materials hard to be abandoned, the liquefaction of several wood polymer composites (WPC), which contains polystyrene and poly(methyl methacrylate), were investigated by the same method. However, these liquefaction did not proceed well, because the polymer impregnated into wood would hinder the affinity between solvent and wood.As the waste plant materials, the liquefaction of rice flour, rice straw, stem of Solidago altissima and leaves of various trees (Larix leptolepis, Zelkova serrata and Ginkgo biloba) were investigated by using same solvent and catalyst. As the results, rice straw and tree leaves were found generally to resist to the liquefaction. On the other hand, rice flour and stem of Solidago were found to be easy to liquefy. The liquefaction of rice straw was improved by alkaline pre-treatment. The products obtained from rice flour and stem of Solidago also were shown to afford the resins by reacting with various epoxy compounds. These cured resins display almost the same behavior as those from wood in the measurement of temperature dependence of viscoelastic properties.