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首页> 外文期刊>Journal of Applied Polymer Science >Effect of Different Catalysts on Urea–Formaldehyde Resin Synthesis
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Effect of Different Catalysts on Urea–Formaldehyde Resin Synthesis

机译：不同催化剂对脲醛树脂合成的影响

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摘要

Four catalysts (H_2SO_4, HCl, H_3PO_4, and NaOH/NH_4OH) were studied in the preparation of melamine modified urea– formaldehyde (UFM) resins. ~(13)C-nuclear magnetic resonance spectroscopic analysis of the UFM resins at different synthesis stages revealed the polymer structure and detailed reaction mechanism. Three acidic catalysts (H_2SO_4, HCl, and H_3PO_4) enhanced the resin polymerization through the formation of various contents of methylene, ether linkages, and urons. H_3PO_4 yielded the most terminal ether linkages at the first stage and enhanced polycondensation by depleting all free urea and glycols to form the most linear methylene linkages NHCH_2NH in the end. However, at the initial synthesis stage, NaOH/NH_4OH catalyzed the formation of UFM prepolymer to a limited extent with a large amount of free urea left, and therefore produced the final polymer with relatively more substituted methylolureas and linear ether linkages.
机译：研究了四种催化剂（H_2SO_4，HCl，H_3PO_4和NaOH / NH_4OH）在三聚氰胺改性的脲醛树脂（UFM）的制备中的作用。对UFM树脂在不同合成阶段的〜（13）C核磁共振光谱分析揭示了聚合物的结构和详细的反应机理。三种酸性催化剂（H_2SO_4，HCl和H_3PO_4）通过形成各种含量的亚甲基，醚键和脲酮来增强树脂聚合。 H_3PO_4在第一阶段产生最多的末端醚键，并通过消耗所有游离尿素和二醇以最终形成最线性的亚甲基键NHCH_2NH来增强缩聚反应。然而，在初始合成阶段，NaOH / NH_4OH在有限的程度上催化了UFM预聚物的形成，并留下了大量的游离尿素，因此产生了具有相对更多取代的羟甲基脲和线性醚键的最终聚合物。

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