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以模型化合物为思维方式,采用电喷雾电离质谱仪(ESI-MS)来研究脲醛树脂(UF)在碱性环境下的相关反应进程和相关机理。研究结果表明,尿素羟甲基化过程是可逆的;碱性条件下羟甲基化可能会形成四羟甲基脲,其中有醚键(-NRCH_2 OCH_2NR-)和桥键(-NRCH_2NR-)。ESI-MS中215、245、275质荷比峰值对应的是醚键结构,227、257质荷比的峰对应的是桥键结构。桥醚键结构的形成具有竞争关系。增加温度对最终UF结构的分布影响不大,但起始反应物摩尔浓度的提高有利于缩聚反应。
Taking the model compound as the thinking mode, the related reaction process and related mechanism of urea formaldehyde resin (UF) in alkaline environment were studied by electrospray ionization mass spectrometry (ESI-MS). The results showed that the methylation of urea was reversible. Hydroxymethylation could form tetramethylol urea under alkaline conditions, including the ether bond (-NRCH 2 OCH 2 -NR-) and the bridge (-NRCH 2 NR-). ESI-MS 215,245,275 mass-to-charge peak corresponds to the ether bond structure, 227,257 mass-to-charge ratio peak corresponds to the bridge structure. The formation of bridge ether bond structure has a competitive relationship. Increasing the temperature has little effect on the distribution of the final UF structure, but increasing the molar concentration of the starting reactant favors the polycondensation reaction.