DSC法研究不同邻对位比值酚醛树脂的固化行为

利用差示扫描量热(DSC)分析技术研究了不同邻对位比值(O/P值)的酚醛树脂的固化活化能及固化进程。采用Ozawa模型求解了不同O/P值酚醛树脂的固化活化能及固化动力学参数,结果表明,酚醛树脂的固化活化能随其O/P值的增加而降低,固化进程变得更加容易。固化反应过程中的Ozawa反应指数n0随着固化反应温度的升高而下降,并且随着树脂O/P值的增加,n0出现在更低的温度区间内。Ozawa反应速度常数k0在固化反应初期随温度的升高而增加,在反应后期则随着温度的升高而下降,并且随着树脂O/P值的增加,k0出现峰值对应的温度降低,表明固化先后经历了微凝胶增长与扩散反应控制两个阶段,树脂O/P值的增加加快了微凝胶的增长进程。

Curing Properties of Novolac-Type Phenolic Resin with Vary O/P Ratios by Differential Scanning Calorimetry

The activation energy of curing reaction and the curing process of phenolic resins with varying O/P ratios were studied by a nonisothermal differential scanning calorimetry(DSC).The activation energy decreased with increasing the O/P ratio.It was also found that the Ozawa exponent values decreased with increasing reaction temperature,and the Ozawa exponent values presented in the lower temperature range with increasing the O/P ratio.The reaction rate constant was found to increase in initial curing stage while decrease in subsequent curing stage with increasing reaction temperature,suggesting a change in the reaction mechanism from microgel growth to diffusion controlled reaction,and the microgel growth rate increased with increasing the O/P ratio.