<正>通过13C-NMR可以很好地解析采用传统工艺碱—酸—碱工艺合成三聚氰胺改性脲醛树脂反应过程中的结构变化，并可推测其发生的反应。结构分析表明：在保温反应开始阶段，尿素与甲醛之间的反应主要为加成反应，产物以一羟甲脲和二羟甲脲为主，并有少量三羟甲脲生成；三聚氰胺与甲醛的加成反应产物为一羟甲基三聚氰胺和二羟甲基三聚羟胺；缩聚反应已经发生，一羟甲脲，一羟甲基三聚氰胺，一羟甲脲与一羟甲基三聚氰胺间的缩聚反应已经开始，分子间以醚键和次甲基键连接为主。保温反应结束直到整个反应结束，缩聚反应为主要反应类型，三聚氰胺改性脲醛树脂中存在着3种反应体系：尿素甲醛的反应体系、三聚氰胺甲醛反应体系和三聚氰铵尿素甲醛共缩合反应体系。

Surface roughness is an important parameter of surface quality in the course of panel furniture manufacturing. In this study, the parameters of surface roughness of medium density fiberboard (MDF) such as average roughness (Ra), maximum individual peak-to-valley height (Ry) and mean peak-to-volley space (Sm) were measured with outline testing method during the different 15 stages after being sawed. The result indicated that the parameters of Ra、Ry and Sm were influenced by leaving time. Ra and Ry have a definite positive linearly correlation with leaving time. Sm has a negative linear correlation with leaving time. It was concluded that the surface roughness of board displays linearly relation with leaving time after being sawed. It was helpful in the determination of the processing time of following procedures in manufacturing.