基于松香酸酐的环氧树脂体系固化动力学及TTT图绘制

研制了基于松香酸酐固化剂的生物质环氧树脂体系,采用全动态DSC法研究了树脂体系的固化反应动力学,通过半经验的唯象模型拟合得到了固化反应参数,活化能Ea为59.68 kJ/g,指前因子A0为1.28×1015s-1,反应级数n为2.483,由此建立了体系固化温度/时间/固化度间的关系;采用恒温DSC及DMA方法测试玻璃化转变温度,应用DiBenedetto经验方程拟合得到了玻璃化转变温度与固化度间的关系.应用锥板旋转黏度计测试了树脂体系不同温度下的凝胶时间,通过线性回归分析得到了凝胶时间与温度之间的关系.由唯象模型和DiBenedetto方程分别计算得到凝胶时的固化度为0.386,玻璃化转变温度为26.22°C.由上述工作绘制了基于松香酸酐生物质树脂体系的TTT(time-temperature-transition diagram)固化图,可确定树脂体系在不同温度任意时间下的状态.

Curing Kinetics and Isothermal Transformation (TTT) Diagram of Epoxy Resin Using Rosin-based Acid Anhydride as Curing Agent

A novel bio-based epoxy resin system,which aimed to be used for hot melt prepreg curing at mid-temperature,was developed from epoxy resin (E51),using rosin-sourced acid anhydrides as curing agent and imidazole as latent catalyst.The temperature-time-transition property of the thermosetting resin wit bio-sourced material was studied.The cure kinetics of the rosin-based resin system was investigated by dynamical differential scanning calorimeter (DSC).The parameters of the cure reaction were obtained by a phenomenological model fitting,which gave 9.68 kJ/g for the activation energy,1,28 × 1015 s-1 for the constant factor and 2.483 as the reaction order,respectively.The relationship between the curing degree and the reaction time at varied temperature was established according to the model used.At temperature above 100 ℃,the curing degree increased quickly with time.On the contrary,at temperature below 1 00 ℃,the curing degree increased slowly with time.For example,the resin system was cured for 180 min at 130 ℃,the curing degree reached 90％ or higher.These results indicated that the resin can realized mid-temperature curing with good stability.Furthermore,the glass transition temperature of bio-based epoxy system was measured using DSC and dynamic mechanical analysis (DMA),and their dependence on the curing degree was obtained based on DiBenedetto equation by regression analysis and the glass temperature transition curves.Moreover,the gelation behavior of the bio-based resin system was studied using a cone plate viscometer.An equation between gel time and temperature was obtained by conducting linear regression analysis.The cure degree and glass transition temperature at gelation,calculated by phenomenological model and DiBenedetto equation,were 0.386 and 26.22 ℃,respectively.Finally,the equivalent curing degree,glass temperature transition and gelation were plotted versus time and the temperature-time-transition (TTT) diagram was formed for the bio-based resin system,which might serve as a powerful tool for manufacturing composite materials or semi-finished products.From this TTT diagram,the state of the resin system could be known at any temperature for any time,and the applicable laminate processing conditions by hot press method was therefore determined.