Kinetic study of epoxy-amine microwave cure reactions. Part I: design and operation of a single-mode resonant microwave cavity

The design and operation of a single mode. tunable, cylindrical microwave c avity is described. The cavity has been used to monitor the cure reactions of two epoxy-amine resin systems. The cavity operates at a microwave freque ncy of 2.45 GHz and a typical power in the range 0-8 W. It is fitted with a n adjustable shorting plate which allows six different electromagnetic mode s to be tuned. The isothermal cure of the resins MY721/DDS and MY721/DDM wa s monitored using fibre optics coupled with a Perkin Elmer 1600 FT-IR spect rometer operating in the NIR region. This allowed simultaneous, real time m onitoring of the intensities of the primary and secondary amine overtone ba nds, as well as that of the epoxide groups. The temperature of the resins d uring cure was monitored by a fibre optic thermometer and was kept constant either by adjustment of the incident microwave power or by on-off switchin g of the microwave field.