聚乙烯亚胺与尿素合成高支化聚脲及其胶接性能

Synthesis and adhesive properties of highly branched polyurea with polyethyleneimine and urea

以支化聚乙烯亚胺(PEI)和尿素(U)经过脱氨缩聚反应,一步法合成高度支化的脲基聚合物;将其配制成50%的水溶液作为木材胶黏剂,制备胶合板;对所制备胶合板进行胶合强度以及耐水性能试验,并研究了PEI的分子质量以及U/PEI的摩尔比对胶合强度的影响。试验结果表明:PEI相对分子质量为1 800,U/PEI摩尔比为3∶1时,胶合板的综合性能最佳,其干强度达到了2.38 MPa, 63℃热水和沸水浸渍3 h后的湿强度分别为2.22和1.41 MPa。利用^(13)C NMR、FT-IR对所制备的脲基聚合物结构进行了表征,结果表明U与PEI发生脱氨缩聚反应,成功合成出U-PEI支化脲基聚合物;进而利用DSC和TGA研究了聚合物胶黏剂的固化性能及热稳定性能,分析结果显示聚脲胶黏剂具有较好的热稳定性。为了证明该脲基聚合物可以应用到更多领域,本研究采用综合性能最佳的脲基聚合物测试了其在不同基材表面的胶接性能。测试结果显示,其在不锈钢、铝和钢化玻璃表面的黏接强度超过了4 MPa,脲基的引入增强了内聚力,同时增强了表面黏附力。

In this study,a highly branched ureido polymer was synthesized with branched polyethyleneimine(PEI) and urea(U) through the deamination polycondensation reaction by a one-step method,which can be used as wood adhesives after being compounded by the deionized water to make an aqueous solution with a solid content of 50% for preparing plywood.These adhesives are alkaline and have moderate viscosity.The bonding strength and water resistance of the prepared plywood were tested.The influence of the molecular weight of PEI and the molar ratio of U/PEI on the bonding strength was studied.The results showed that,when the relative molecular weight of PEI is 1 800 and the molar ratio of U/PEI is 3∶1,the plywoods have the best comprehensive properties.As expected,the dry strength of the plywood reached 2.38 MPa,and the wet strength of the plywood impregnated with 63 ℃ hot water and boiling water for 3 h were 2.22 MPa and 1.41 MPa,respectively.The structure of the prepared ureido polymer was characterized by^(13)C NMR and FT-IR.The results showed that the deamination polycondensation reaction between U and PEI occurred,and the U-PEI branched ureido polymers were successfully synthesized.Then,the curing property and thermal stability of the polymer adhesive were studied by DSC and TGA.The analysis results showed that the polyurea adhesives had good thermal stability.In order to prove that the ureido polymers can be applied in more fields,a large number of experiments were carried out.The ureido polymers with the best comprehensive properties were used to test its cementing performance on different substrate surfaces.The test results showed that the bonding strength on the surface of stainless steel,aluminum and toughened glass were more than 4 MPa.The introduction of the urea groups made the system containing a large number of amino and carbonyl groups.The ureido polymers can form ionic coordination with the stainless steel and aluminum surfaces,and form strong hydrogen bond with the toughened glass surface,because the superimposed hydrogen bond occurred between its molecules.The previously mentioned characteristics made the polymers to have great bonding properties on the different substrate surfaces.