pH值对酚醛树脂性能的影响

摘要

为了探究pH值对酚醛树脂(PF)理化性能及其压制的胶合板性能的影响,实验分别合成了pH值为10、11、12和13的四种PF树脂,并重点分析了树脂的游离甲醛、游离苯酚、凝胶时间、胶合强度和甲醛释放量的变化规律.通过FT-IR和13C-NMR对不同pH值的PF树脂进行了结构表征,利用旋转流变仪研究了树脂的固化速度.实验结果表明随着树脂的pH值升高,PF树脂的游离苯酚和游离甲醛的含量均呈下降趋势,凝胶时间先缩短后变长,固化速度先加快再变慢.当pH值为12时,PF树脂和胶合板的性能达到最佳.%The phenol-formaldehyde resin (PF) was synthesized at different pH (10,11,12 and 13) in order to explore the effects of pH on the physical and chemical property of PF and on the property of PF pressed plywood.The change rule of free phenol,free formaldehyde,gel time,bonding strength and formaldehyde emission of PF resins was studied in detail.The structure and curing behavior of PF synthesized at different pH were characterized by using FT-IR and 13C-NMR and rotational rheometer.It is found that the content of free phenol and free formaldehyde of PF decline with increasing of pH,and the gel time of resins initially decreases and then increases.PF prepared at the pH value of 12 shows the best performance of plywood.