聚乙烯亚胺/聚磷酸铵复合聚电解质对脲醛树脂固化行为的影响及其阻燃木质刨花板  

Polyethyleneimine/ammonium polyphosphate polyelectrolyte complex effects on the curing behavior of urea-formaldehyde resin and its flame retardant wood particle board

作　　者：王帅旗 张宇婷 张帅 梅长彤 潘明珠 WANG Shuaiqi;ZHANG Yuting;ZHANG Shuai;MEI Changtong;PAN Mingzhu(School 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：《复合材料学报》2023年第12期6583-6595,共13页Acta Materiae Compositae Sinica

基　　金：十四五国家重点研发计划、课题(2021YFD2200602-4)。

摘　　要：木质复合材料的阻燃处理和力学增强一直受到广泛的关注。阻燃剂的加入不仅会增大胶黏剂的黏度,而且阻燃剂中的活性基团可以通过化学交联键合到树脂分子上,阻碍胶黏剂的聚合过程,从而对树脂的固化过程产生不利影响。通过对阻燃剂的改性,使其能够提高胶黏剂的固化反应性,增强胶黏剂的粘接强度,同时可以最大限度地减少阻燃剂的迁移,有效提升材料的阻燃性能和力学强度。鉴于此,本文以聚磷酸铵(Ammonium polyphosphate,APP)和聚乙烯亚胺(Polyethyleneimine,PEI)为阴、阳离子聚电解质,通过自组装制备复合聚电解质(PEI/APP),并进一步将其应用于木质刨花板中。PEI/APP提高了脲醛树脂(Ureaformaldehyde resins,UF)的固化反应性,同步赋予了刨花板优异的力学强度和阻燃性能。基于Kissinger和Ozawa动力学方程计算了不同添加量的PEI/APP与UF交联体系的活化能(E_(a)),重点研究了PEI/APP对UF固化动力学的影响。结果表明:PEI/APP能够通过酰胺键和氢键作用与UF形成分子交联网络,促进UF的缩聚固化过程,使E_(a)随着PEI/APP添加量的增加而逐渐减小,热固化的反应性逐渐提高,UF的固化放热峰值温度(TP)逐渐降低。与此同时,PEI/APP与UF形成的交联网络增强了木质刨花的内聚强度及界面结合,刨花板的各项物理力学性能均得到了明显提高。当PEI/APP添加量为10wt%时,刨花板拥有最高的弹性模量(MOE)和静曲强度(MOR),分别为3368.46 MPa和27.18 MPa。此时刨花板的极限氧指数(Limiting oxygen index,LOI)为46.3%,热释放速率峰值(PHRR)降为170.3 kW/m^(2),相较于未处理和APP阻燃刨花板分别降低了45.3%和22.3%。PEI/APP受热产生的聚磷酸能够促使有机物脱水炭化产生膨胀炭层,其致密连续的内、外炭层有效阻止了气相和凝聚相之间的传热和传质。PEI/APP能够促使UF在较低温下发生固化,同步赋予刨花板良好的工艺性能、阻燃性能和力The flame retardance treatment and mechanical enhancement of wood composites have been widely concerned.The addition of flame retardants not only increases the viscosity of the adhesive,but also the reactive groups in the flame retardant can be chemically cross-linked to the resin molecules,hindering the polymerization process of the adhesive,which affects the curing process of the resin.Through the modification of the flame retardant,it can improve the curing reactivity and enhance the bonding strength of the adhesive,while minimize the migration of the flame retardants,effectively improve the flame retardant properties and mechanical strength of the materials.Herein,we prepared polyelectrolyte complex polyethyleneimine(PEI)/ammonium polyphosphate(APP)by self-assembly using APP and PEI as anionic and cationic polyelectrolytes,and further applied it to wood particle board.PEI/APP enhances the curing reactivity of urea formaldehyde resin(UF)and simultaneously endow particle board with excellent mechanical strength and flame retardant properties.The activation energy(E_(a))of UF and different PEI/APP additions are calculated based on Kissinger and Ozawa kinetic equations,focusing on the effect of PEI/APP on UF curing kinetics.It is indicating that PEI/APP and UF formed a molecular crosslinking network through amide bonding and hydrogen bonding,facilitating the condensation and curing process of UF,resulting in E_(a) decreasing gradually with the increase of the content of PEI/APP,the curing reactivity increasing gradually and the curing exothermic peak temperature(TP)of UF decreasing gradually.Meanwhile,the cross-linked network formed between PEI/APP and UF enhanced the cohesive strength and interfacial bonding of wood particles,and the physical and mechanical properties of particle board were improved significantly.When the content of PEI/APP is 10wt%,the particle board has the highest modulus of elasticity(MOE)and modulus of rupture(MOR),which are 3368.46 MPa and 27.18 MPa respectively.Meanwhile,the limiting oxyg

关 键 词：刨花板 复合聚电解质 脲醛树脂固化动力学 力学增强 阻燃机制 聚磷酸铵 聚乙烯亚胺 

分 类 号：TB332[一般工业技术—材料科学与工程] TQ323.3[化学工程—合成树脂塑料工业]