CHEMO-RHEOLOGICAL CHARACTERIZATION OF EPOXY- AMINE THERMOSETS WITH EMBEDDED REACTIVE MATERIALS

摘要

Epoxy matrix materials are well utilized and studied in composites. We think it is desirable to produce epoxy-amine matrix materials that contain embedded latent reactive materials for use after cure and during utilization. A concern developed during our blending experiments was related to potential competing mechanisms between the additive material and the parent matrix epoxy and amine functional groups. For the paper presented here, blocked isocyanates synthesized by reacting isophorone diisocyanate individually with JV-methyl aniline, e-caprolactam and 4-hydroxy TEMPO were incorporated into epoxy-amine thermosetting systems as embedded agents. Near infrared (NIR) spectroscopy and dynamic rheology were used in combination to quantify the effects of conversion at 30 ℃ in the presence and absence of reactive additives. Compared to the control (no additive), variations in gel points and ultimate epoxy conversion were observed in systems containing blocked isocyanates based on JV-methyl aniline and e-caprolactam, however, no significant variation was detected with the 4-hydroxy TEMPO blocked isocyanate. The kinetic rate of the epoxy-amine reaction, measured by NIR, decreased by approximately 0.0015 mol~*kg~(-1)min~(-1) for every 5 wt% of additive within the matrix. The consistent loss of reaction rates with increasing additive concentration suggests that the effect on kinetic rate is due to decreasing concentration of reacting functional groups and was not attributed to the presence of a competing mechanism.