酸酐分子结构对金属箔电阻器环氧粘接剂材料热力学性能影响的研究

Study on effect of molecular structure of anhydride on thermodynamic properties of epoxy adhesive material for metal foil resistor

为获得金属箔电阻器用高热稳定性环氧粘接剂材料,采用分子模拟计算结合实验的方法研究了甲基六氢苯酐(MeHHPA)、甲基四氢苯酐(MeTHPA)和六氢苯酐(HHPA)的分子结构对金属箔电阻器环氧粘接剂材料热力学性能的影响。首先分别建立了3种酸酐分子与芴基环氧树脂(DGEBF)的交联模型,并通过分子模拟计算分析了交联模型的宏观热力学参数,其次从微观参数方面解释了酸酐分子结构对交联体系热力学性能影响的机理,最后通过实验对仿真结果进行了验证。结果表明:六氢邻苯二甲酸酐体系具有最小的自由体积和均方位移,自由体积占比仅为15.15%。实验中,3种酸酐固化体系的热力学性能变化趋势与模拟计算结果相吻合,六氢苯酐体系的热力学性能最好,其玻璃化转变温度达435 K,弯曲强度达84.46 MPa,体积热膨胀系数仅为1.65×10^(-4)K^(-1)。

In order to obtain epoxy adhesive materials with high thermal stability for metal foil resistors,combining with molecular simulation and experiment,we studied the effects of molecular structures of methyl hexahydrophthalic anhydride(MeHHPA),methyl tetrahydrophthalic anhydride(MeTHPA),and hexahydrophthalic anhydride(HHPA)on the thermodynamic properties of epoxy adhesive materials for metal foil resistors.Firstly,the cross-linking models of three kinds of acid anhydride molecules and fluoren-based epoxy resin(DGEBF)were established,respectively,and the macroscopic thermodynamic parameters of the cross-linking models were analyzed through molecular simulation calculation.Secondly,the influence mechanism of the molecular structure of acid anhydride on the thermodynamic properties of the cross-linking system was explained according to microscopic parameters.Finally,the simulation results were verified by experiments.The results show that hexahydrophthalic anhydride system has the smallest free volume(FFV)and mean square displacement(MSD),and the free volume proportion is only 15.15%.In the experiment,the change trend of thermodynamic properties of the three kinds of curing anhydride system is consistent with the simulation results.The hexahydrophthalic anhydride system has the best thermodynamic performance,and its glass transition temperature reaches 435 K,bending strength reaches 84.46 MPa,and volumetric thermal expansion coefficient is only 1.65×10^(-4) K^(-1).