The Research Of Properties And Curing Behaviors Of Polyethenoxyamines And Isophoronediamine

In this article, as the main component of epoxy curing agent, poly -ethenoxyamines and isophoronediamine were studied from some aspects: appearance of hardener/epoxy systems, analysis of micro-structures of both curing agent, curing process of both hardener/epoxy systems.It is easy to consider that the reactivity of each amine is similar, because both of polyethenoxyamines and isophoronediamine are diamine and because amino groups and their vicinity groups are similar in molecure structures. Accidentally, it was found that appearances of them, which is one of the key factors for industry application, were quite different after 48 hours exposure to the air. The transparency of polyethenoxyamines system is better than isophoronediamine system and there is no smoke formation during curing procedure.First, reactivities of them are studied and demonstrated through weight observation, FTIR, ~1H-NMR and MS. The weight observation, which is increasing obviously, shows that two kinds of diamine have changed either in chemistry or physics in the air. Analytical results of FTIR and ~1H NMR characteristics indicate that: 1, the change of weight of polyethenoxyamines is only influenced by the absorption of water; 2, isophoronediamine reacts with water and carbon dioxide after exposure to the air, which results in the change of weight. In conclusion, the key factor for the different reactivity of polyethenoxyamines and isophoronediamine is explained by the hydrogen bond of ployethenoxy amine formed between amino groups and oxide atom of main chain, which lower the reactivity of amine groups in polyethenoxyamines.In addition, the hot plate was used to measure the gelling time of the two hardener/epoxy systems at different temperature. The result shows that the curing rate of polyethenoxyamines/epoxy is lower than isophoronediamine /epoxy. Curing behaviors of two hardener/epoxy system were investigated by DSC respectively. Moreover, activation energy are calculated from DSC datas, which also indicate that the reactivity of polyethenoxyamines is lower than isophoronediamine and also prove our hydrogen-bonding theory mentioned above.At last, we succeed in finding a curing agent which overcomes the shortcomings of isophoronediamine based hardener. Meanwhile, the new curing agent maintains the reasonable hardness and toughness and enhances the adhesive property with glass.