The influence of the molecular weight of oligoamine, oligoether, and the type of diisocyanate on the physical and mechanical properties of elastomers with urethane hydroxyl hard segments was studied. For this purpose, oligoetherdiamines with molecular weights ~1008 and ~1400 g mol−1 were synthesized by a three-stage method. Epoxyurethane oligomers were synthesized according to a two-step route with an oligodiisocyanate as an intermediate product. A series of 12 elastomers with controlled crystallinity were synthesized from these elastomers and amines. The deformation and strength properties of the elastomers were studied.
A modified synthetic method for amino-terminated oligo tetramethylene oxides is presented. Diamines were synthesized via a three-step route from oligo tetramethylene oxide diol with an average molecular weight of 2000. The final step – oligoether-diphthalimide hydrazinolysis – has been improved. The yield of the target product has been shown to be more than 1.5 times higher when the molar ratio of the reacting components was changed. The oligoether-diamine and the reaction intermediates have been identified by 1H and 13C NMR spectroscopy. It has been demonstrated that the synthesized amine can be used as a curing agent for epoxy urethane oligomers. It is shown that the glass transition temperature of the cured elastomers is lower than −70 °C. These elastomers can be recommended for the use in the conditions of the Arctic and the Far North or Far South of the globe.
A new bifunctional epoxy resin was synthesized by the reaction of replacing the hydrogen atom of amino groups from 4,4-diaminodiphenylmethane and epichlorohydrin taken in a double excess in dichloroethane. In order to remove HCl formed during the synthesis, which can interact with the initial diamine, as well as with the oxirane rings of both epichlohydrin and the synthesized product, an excess of potassium carbonate was introduced into the reaction mixture. The structure of the synthesized epoxy resin - 4,4′-methylenebis (N- (oxiran-2-ylmethyl) aniline) was characterized and proved by the methods of FTIR spectroscopy, nuclear magnetic resonance and elemental analysis. The kinetic parameters of the synthesized resin were characterized by differential scanning calorimetry. Using the Kissinger method, the activation energy of the self-curing reaction was calculated, the value of which was 1.139 kJ / mol. Such a low activation energy of epoxy resin allows to cure at low temperatures, but shortens the storage time. Two curing modes were studied: 1 mode - 10 hours at 150 ° C, 2 step mode - 10 hours at 150 ° C + 3 hours of postcuring at 180 ° C.
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