脲醛树脂固化过程的热机械性能分析

为了进一步了解脲醛树脂的固化过程，用热机械性能分析（TMA），同时辅以差式扫描量热法（DSC）分析和胶合性能测试，分析了TMA图谱信息构成，评估了固化剂种类和固化剂用量对脲醛树脂固化的影响。结果表明:①TMA图谱可以提供脲醛树脂固化反应起始温度、固化反应速率、固化后树脂机械性能以及固化后树脂热稳定性能等信息，这些信息与DSC和胶合性能测试的结果互相印证。②不同固化剂种类对脲醛树脂固化起始温度和固化速率影响各不相同。在该研究范围内，增加固化剂用量对脲醛树脂固化起始温度、固化速率等没有显著影响，但过量使用固化剂将导致树脂热解，从而降低树脂机械性能。③较高甲醛/尿素摩尔比的脲醛树脂对固化剂用量改变的反应更为敏感。 

Curing reaction of urea-formaldehyde resin by thermal mechanical analysis.

Thermal mechanical analysis (TMA) is used in this paper to study the curing reaction of urea-formaldehyde (UF) resins. The relative information from TMA was examined by differential scanning carlorimetry (DSC) and laboratory-made particleboard. The effects of types and amount of hardener added on the curing of resin were discussed too. The results showed that TMA could be used to evaluate the beginning curing temperature, curing speed, mechanical performance and thermal resistance of resin system. These data from TMA were confirmed by the results of DSCand particleboard. It indicated that different hardener had different beginning temperature and curing speed; however, there were no obvious effects on both of them for UF resin when using more hardener. When too much hardener was used, pyrolysis of resin could happen and then the decreased mechanical performance was observed. UF resin with higher molar ratio F/U seems to be more sensitive to the amount of hardener added.