摘要
为提升尿素-乙二醛树脂(UG)的耐水性能,本研究在UG树脂中添加高活性的异氰酸酯(MDI)共混制备了异氰酸酯/尿素-乙二醛(MDI-UG)木材胶黏剂。采用傅里叶变换红外光谱(FT-IR)、核磁共振波谱仪(NMR)和X射线光电子能谱(XPS)对其固化结构进行表征,通过差式扫描量热分析(DSC)、动态热机械分析(DMA)和扫描电镜(SEM)对其固化性能进行分析,以MDI-UG混合体系制备胶合板并测定其力学性能。结果表明UG树脂中含有的活泼氢基团与异氰酸酯反应形成新的氨基甲酸酯;与UG树脂相比,MDI-UG树脂的固化温度降低且热稳定性提高;采用扫描电镜下可观测到MDI-UG树脂的固化颗粒更加密集且交联支化程度明显提高;当MDI的添加量为3%且乙二醛与尿素的摩尔比为1.3:1时,所制得胶合板的热水湿状剪切强度达到0.72 MPa,表明MDI的引入显著改善了UG树脂的耐水性,而且充分发挥了UG树脂优异的环保性能和异氰酸酯的高强度特点。
In order to enhance the water resistance of urea-glyoxal resin(UG),isocyanate/urea-glyoxal(MDI-UG) wood adhesive was prepared in this study by blending with highly active isocyanate(MDI) in UG resin.The cured structures were characterized by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance spectroscopy(NMR) and X-ray photoelectron spectroscopy(XPS),and the curing properties were analyzed by differential scanning calorimetry(DSC),dynamic thermo-mechanical analysis(DMA),and scanning electron microscopy(SEM),and the plywood were prepared with the MDI-UG blended system and their mechanical properties were determined.The results showed that the active hydrogen groups contained in the UG resin reacted with the isocyanate to form a new urethane;the curing temperature of the MDI-UG resin was reduced and the thermal stability was improved compared with that of the UG resin;the cured particles of the MDI-UG resin were more densely packed and the degree of cross-linking and branching was significantly improved by using the scanning electron microscopy(SEM);the curing properties of the MDI-UG resin were improved by using the MDI-UR system with the addition of 3% of the MDI and the molar ratio of glyoxal to urea of 1.3:1.When the addition amount of MDI is 3% and the molar ratio of glyoxal to urea is 1.3:1,the hot water wet shear strength of the produced plywood reaches 0.72 MPa,which indicates that the introduction of MDI significantly improves the water resistance of the UG resin,and gives full play to the excellent environmental protection performance of the UG resin and the highstrength characteristics of the isocyanate.
作者
杜旭韬
李奇恒
汪进文
杜官本
邓书端
DU Xu-tao;LI Qi-heng;Wang Jin-wen;DU Guan-ben;DENG Shu-duan(Key Laboratory of wood adhesive and glued products of Yunnan province,Southwest Forestry University,Kunming 650224,Yunnan,China)
出处
《化学研究与应用》
CAS
北大核心
2024年第1期92-102,共11页
Chemical Research and Application
基金
云南省基础研究重点项目(202201AS070152)
杜官本院士工作站(YSZJGZZ-2020052)
高等学校学科创新引智计划资助项目(D21027)
大学生创新创业训练项目。
