Competitive polycondensation of model compound melamine-urea-formaldehyed(MUF)resin system by^(13)C NMR  

作　　者：Jiankun Liang Quan Li Zhigang Wu Guanben Du Taohong Li Hong Lei Lifen Li 

机构地区：[1]Kaili University,Qiandongnan 556011,China [2]College of Forestry,Guizhou University,Guiyang 550025,China [3]Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products,Southwest Forestry University,Kunming 650224,China

出　　处：《Journal of Bioresources and Bioproducts》2020年第1期60-66,共7页生物质资源与工程（英文）

基　　金：This work was supported by National Natural Science Foundation of China(Nos.31800481 and 31870546);Education Depart-ment Foundation of Guizhou Province of China(No.[2019]184);Science-technology Support Foundation of Guizhou Province of China(Nos.[2019]2308 and[2019]2325);Forestry Department Foundation of Guizhou Province of China(Nos.[2017]14 and[2018]13).

摘　　要：Melamine-urea-formaldehyde(MUF)resin is an excellent adhesive in the field of wood adhe-sives,however the competition mechanism is questionable which affects the structure control and performance optimization of the resin.In this study,the competitive resin synthesis poly-condensation reaction of MUF system under alkaline condition was studied based on the model compound 1,3-dihydroxymethyl urea(UF_(2))and melamine(M)system,and the competitive reac-tion mechanism in the system was deduced by^(13)C NMR quantitative analysis.The results show that the energy barrier of hydroxymethylation of melamine is lower than that of urea,and the priority of hydroxymethylation is lower;the addition of melamine results in a large amount of hy-drolysis of UF_(2),and the formed free formaldehyde,resulting in hydroxymethylation of melamine;there is obvious polycondensation reaction in UF_(2)+M system,mainly from the relationship be-tween hydroxymethylurea and melamine or hydroxymethylmelamine.The type I bridge bond structure of polycondensation mainly comes from the reaction of UF_(2) and M,which is difficult to form the type II bridge bond.At low molar ratio,the formation of bridge bond is superior to that of ether bond.With the increase of molar ratio,the formation of ether bond shows advantages,but there is obvious competition between them.There may be competitive presence of the UF self-condensation products,melamine-formaldehyde(MF)self-condensation products and MUF co-condensed products after the polycondensation reaction.

关 键 词：Model compound Melamine-urea-formaldehyde(MUF) COPOLYCONDENSATION COMPETITIVENESS 

分 类 号：TQ432[化学工程]