Effect of montmorillonite modified by poly (oxypropylene) amines on curing process of epoxy nanocomposites

Five kinds of Montmorillonite (MMT) modified by poly (oxypropylene) (POP) amines were prepared. Each of these modified MMT (O-MMT) was added into epoxy (EP) E51 and hardener POP amine D400 to yield an EP/MMT mixture. Differential scanning calorimetry (DSC) was used to investigate effect of these five MMTs modified by POP amines on epoxy curing process at a heating rate of 10°C/min. Then isothermal curing kinetics of neat epoxy and an EP/D400-T5000-MMT mixture was studied by DSC at different temperatures (130, 140, 150 and 160°C). Kamal model was used to calculate the kinetics parameters of the isothermal curing of these two EP systems. The results show that the cure process of EP was found to be influenced by the presence of MMT modified with POP amines. Compared with that of neat EP, exothermic peak of DSC curve of EP/O-MMT shifted to higher temperature, while co-intercalation of POP amine D400 weakened the effect of POP amine D2000 and T5000 on EP curing. At the same isothermal curing temperature, two curing rate constants, k₁ and k₂, and curing reaction order m of the EP/D400-T5000-MMT mixture were smaller than that of neat EP system, but curing reaction order n and the overall reaction order m+n of the EP/D400-T5000-MMT mixture were larger than that of neat EP system. Thus means that D400-T5000-MMT decreases the rate of epoxy curing reaction. In addition, compared with that of neat EP system, the curing reaction activation energy of EP/D400-T5000-MMT mixture increased slightly.