The effect of urea addition numbers and interval on the curing behavior of urea-formaldehyde resin, which was synthesized under initial weak acidity condition, was investigated. The curing process of urea-formal- dehyde resin was studied by using differential scanning calorimetry （DSC）. The curing apparent activation en- ergy and reaction grade were calculated, and the curing reaction equation was founded under different urea ad- dition numbers and interval. The results showed that the addition numbers and interval notably affected curing reaction of urea-formaldehyde resin. With the addition numbers and interval increased, the apparent activation energy of curing system of resins was reduced. The curing reaction of UF resins was non-elementary reaction and the reaction grade was between 0.92 and 0.93 when it was synthesized under initial weak acidity condi- tions.%为了研究尿素对弱酸性起始合成的UF树脂固化性能影响,采用DSC研究了弱酸性起始合成UF树脂中碱性加成阶段尿素添加次数和间隔时间对树脂固化反应动力学影响.计算了碱性加成阶段尿素添加次数和间隔时间不同的UF树脂的固化表观活化能和反应级数,并建立相应的固化反应动力学方程.研究结果表明：弱酸性起始合成UF树脂,碱性阶段尿素添加次数和添加间隔时间影响树脂固化,尿素添加次数增加和尿素添加次数相同而添加尿素时间间隔延长能降低UF树脂固化体系的活化能.弱酸性起始合成UF树脂的固化反应是介于0.92～0.93级之间的非基元反应.
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