Organosolv lignin isolated from cornstalk was activated via alkalification with sodium hydroxide or by sodium hydroxide catalyzed methylolation to make aqueous lignin solution (AL) and methylolated lignin solution (ML). Sodium hydroxide solution well dissolved the organosolv lignin even though the viscosity of AL was comparatively higher than that of ML. Different from traditionally replacing phenol with lignin during phenolic formaldehyde (PF) resin synthesis, this study applied the activated lignin as reactive prepolymers that could polymerize directly with neat phenol formaldehyde resin (NPF) under curing for production of wood adhesives. It was found that the lignin/NPF adhesives with or without methylolation cured more easily than the NPF, although the Lignin/NPF adhesives were slightly less thermally stable than the NPF. When applied as a binder to 3-ply plywood, the NPF led to dry and wet bonding strength of 2.33 MPa and 2.09 MPa, respectively. The AL/NPF (25/75, w/w) adhesive resulted in reduced dry and wet bonding strengths of 1.88 MPa and 1.74 MPa, respectively, but AL/NPF adhesive with a higher AL/NPF weight ratio of 50/50 reduced the dry strength to 1.03 MPa, and caused delamination of the 3-ply plywood when heated in boiling water. Lignin methylolation however greatly enhanced the dry/wet bonding strengths of the 3-ply plywood. The ML/NPF (50:50) adhesive produced 3-ply plywood with dry and wet tension shear strengths of 1.45 M P and 1.43 MPa, respectively, both above the ASTM or JIS standard requirements for plywood. In particular, 3-ply plywood samples with ML/NPF (25/75) adhesive afforded superb dry and wet strengths of 2.34 MPa and 2.30 MPa, respectively, even higher than those of the NPF-bonded samples. In addition, the free formaldehyde emission from the bonded 3-ply plywood with the AL/NPF was lower than that with the NPF, although the use of ML/NPF slightly increased the free formaldehyde emission.

通过用氢氧化钠进行碱化或通过氢氧化钠催化的羟甲基化作用来活化从玉米杆分离的有机溶剂木质素，从而制备出木质素水溶液（AL）和羟甲基化木质素溶液（ML）。即使AL的粘度相对高于ML的粘度，氢氧化钠溶液也能很好地溶解有机溶剂木质素。不同于传统的在酚醛树脂（PF）合成过程中用木质素代替酚的方法，本研究应用了活化的木质素作为反应性预聚物，可以在固化后直接与纯酚醛树脂（NPF）聚合以生产木质胶粘剂。发现具有或不具有羟甲基化的木质素/ NPF粘合剂比NPF更容易固化，尽管木质素/ NPF粘合剂的热稳定性比NPF稍差。当用作三层胶合板的粘合剂时，NPF的干，湿粘合强度分别为2.33 MPa和2.09 MPa。AL / NPF（25/75，w / w）粘合剂导致干，湿粘合强度分别降低1.88 MPa和1.74 MPa，但AL / NPF重量比较高的50/50的AL / NPF粘合剂降低了粘合强度。干燥强度达到1.03 MPa，并在沸水中加热时导致3层胶合板分层。然而，木质素羟甲基化极大地增强了三层胶合板的干/湿粘合强度。ML / NPF（50:50）粘合剂生产的三层胶合板的干，湿拉伸剪切强度分别为1.45 M P和1.43 MPa，均高于ASTM或JIS标准的胶合板要求。特别是，使用ML / NPF（25/75）粘合剂的3层胶合板样品提供了2.34 MPa和2.30 MPa的卓越干，湿强度，甚至比NPF键合样品更高。此外，虽然使用ML / NPF会稍微增加游离甲醛的排放量，但使用AL / NPF的三层胶合板的游离甲醛释放量要低于NPF。