层层自组装聚电解质对胶合板力学及阻燃性能的影响  

Effects of layer by layer self-assembly of polyelectrolytes on mechanical and flame retardant properties of plywood

作　　者：黄燕萍 陆弘毅 张帅 潘明珠 HUANG Yanping;LU Hongyi;ZHANG Shuai;PAN Mingzhu(College of Materials Science and Engineering,Nanjing Forestry University,Nanjing 210037,China)

机构地区：[1]南京林业大学材料科学与工程学院,南京210037

出　　处：《林业工程学报》2022年第6期53-60,共8页Journal of Forestry Engineering

基　　金：国家自然科学基金(32171704)。

摘　　要：以聚磷酸铵(APP)为阴离子聚电解质、聚乙烯亚胺(PEI)为阳离子聚电解质,通过层层自组装技术在单板表面构建PEI/APP阻燃涂层,制备阻燃胶合板。研究了阴、阳离子聚电解质的自组装过程,并探讨其对胶合板胶合强度和阻燃性能的影响规律。结果表明:PEI和APP通过离子交换形成分子交联网络,并进一步与木材表面氢键相互作用,被成功构建到单板表面。与单独组装APP相比,PEI/APP的交替组装能够改善单板表面浸润性,促使脲醛树脂(UF)在单板表面进一步扩散和渗透,与此同时,PEI/APP交联网络能够增强UF树脂体系的交联程度及其在固化过程中的内聚强度,从而改善胶合板胶合强度。当PEI/APP组装层数≤10时,胶合强度均能满足Ⅱ类胶合板强度标准,并且其胶合剪切应变峰值为0.96%,剪切界面应变分布更加均匀,应变集中区域明显减少;同时其极限氧指数(LOI)高达37.4%,热释放速率峰值降为240.40 kW/m^(2),相较于未处理和APP处理胶合板分别降低了30.5%和13.2%。层层自组装PEI/APP能够获得同步阻燃和胶合强度改善的胶合板。Anionic polyelectrolyte of ammonium polyphosphate(APP) and cationic polyelectrolyte of polyethyleneimine(PEI) were used to construct PEI/APP flame retardant coating on the surface of veneer using layer by layer self-assembly(LBL) technology to prepare flame retardant plywood. The self-assembly process of anionic and cationic polyelectrolytes and its effects on the chemical structure of the urea formaldehyde(UF) resin were stu-died. The influence of PEI/APP flame retardant coating on the bonding strength and flame retardant properties of plywood were further discussed. PEI and APP formed a molecular crosslinking network through ion exchanges, and further interacted with the wood surface by the hydrogen bonding and covalent bonding, so that the PEI/APP assembly layer was successfully constructed on the veneer surface. Compared with the assembly of sole APP, the alternative assembly of PEI and APP can improve the surface wettability of the veneer and inhibit the adverse effect of APP on the wettability of veneer. Furthermore, the diffusion and penetration of UF resin on the surface of veneer were promoted. Meanwhile, the cross-linked network formed between PEI and APP can increase the degree of molecular crosslinking in the urea-formaldehyde resin system and enhance the cohesive strength during the UF curing process, thereby, improving the bonding strength of plywood. When the number of PEI/APP assembly layers ≤ 10 layers, the bonding strength can meet the strength requirements of the standard of Class Ⅱ plywood. The peak bonding shear strain was 0.96%, the shear interface strain distribution was more uniform, and the strain concentration area was significantly decreased. It was shown that the PEI/APP assembly layer can form a more stable molecular crosslinking network with the UF resin, so as to improve the stress transfer behavior of plywood and further improve the deformation resistance of internal bonding interface. At the same time, the flame retardancy of plywood was also significantly improved. The limiti

关 键 词：阻燃胶合板 聚磷酸铵 聚乙烯亚胺 层层自组装 应变传递 

分 类 号：TB332[一般工业技术—材料科学与工程] TS653.3[轻工技术与工程]