基于MD模拟的DGEBA平均分子量对环氧树脂热机械性能的影响

Effect of Average Molecular Weight of DGEBA Based on MD Simulation on Properties of Crosslinked Epoxy Resin

平均分子量的大小对双酚A型环氧树脂性能有着显著影响,为此采用分子动力学模拟(MD)方法,将2种不同聚合度的双酚A型缩水甘油醚(DGEBA)按照不同比例混合,以甲基四氢苯酐(MTHPA)为固化剂,研究了不同平均分子量对环氧树脂体系热力学性能的影响,并与聚合度为0的DGEBA/MTHPA体系进行了对比。结果表明:随着平均分子量的增加,体系的玻璃化转变温度(Tg)先升高后降低,但均高于聚合度为0的DGEBA/MTHPA体系;平均分子量对橡胶态体系的热膨胀系数(CTE)影响较为明显;体系的弹性模量呈现先上升后下降的趋势,在平均分子量为700~750时,各个弹性模量的提升幅度最大。

The average molecular weight of bisphenol A-type epoxy resin has a significant effect on its performance.Consequently,two different degrees of polymerization of bisphenol A-type glycidyl ether(DGEBA)were mixed in different proportions by molecular dynamics simulation(MD).The effects of different average molecular weights on the thermodynamic properties of epoxy resin system were studied using methyltetrahydrophthalic anhydride(MTHPA)as a curing agent,and compared with those of DGEBA/MTHPA system with polymerization degree of 0.The results show that,with the increase of average molecular weight,the glass transition temperature(Tg)of the system increases first and then decreases,but both are higher than those of the DGEBA/MTHPA system with a degree of polymerization of 0.The average molecular weight more remarkably affects the thermal expansion coefficient(CTE)of the rubber system.The elastic modulus of the system first rises and then decreases.When the average molecular weight is 700~750,the elastic modulus increases to the most extent.