木质素和聚糖的酶催化交联产物在纤维板中的应用

Enzyme-catalyzed Crosslinking of Lignin and Polysaccharides in Fiberboard

利用木质素前驱物协同果胶在漆酶体系作用下处理麦草纤维,以湿法工艺制造高强度中密度纤维板。实验结果表明:经处理后,纤维板的24 h吸水厚度膨胀率(TS),纤维板的内结合强度(IB),静曲强度(MOR),弹性模量(MOE)分别达到16.7%,0.6 MPa,25.1 MPa,2 500 MPa。各项物理性能指标均达到或超过国家中密度纤维板(GB/T 11718-2009)标准。通过SEM和CP/MAS13C NMR分析可知,在木质素和聚糖(果胶等)之间发生了交联反应,形成了类似胞间层的沉积物,通过苯甲醚、酯键等木质素-聚糖复合体形式的交联以及木质素之间的β-芳基醚键等共价键的连接,从而使纤维之间形成牢固的化学键交联。同时研究还发现,果胶与松柏醇葡萄糖苷很容易生成果胶-DHP复合体,从而进一步提高了纤维板的物理性能,同时降低TS。

In the present research, coniferin- [ a-13C ] is co-polymerized with fibers of Bio-CMP of wheat straw and pectin catalyzed by laecase. A wet method was used for the formation of high-strength fiberboards. The results indicated that the thickness expansion rate of water absorbing （ TS）, the internal bond （ IB ）, the modulus of rupture （ MOR）, and the modulus of elasticity （MOE） reached 16.7 % , 0. 6 MPa, 25.1 MPa and 2 500 MPa,respectively. As a result, all mechanical properties of the medium-density fiberboard （MDF） can meet or exceed the standards of GB/T 11718 -2009. According to CP/MAS 13C NMR, lignin-earbohydrate complexes（LCC） were formed between lignin and polysaccharide. Pectin and xylan in fibers were erosslinked with high through benzyl ether linkages and ester bonds, and β-aryl ether linkages were formed between lignin. Furthermore, pectin and coniferin were easy to form pectin-DHP in the presence of laccase. These complexes and linkages result in a further improvement of mechanical properties of MDF and reduction of TS.