IN-SITU REAL-TIME STUDY OF CROSS-LINKING KINETICS IN THERMAL AND MICROWAVE FIELDS

A comparative investigation has been conducted of the mechanisms and r ate of chemical reactions in thermal and microwave fields. A number of nonpolymer-forming and polymer-forming mixtures of different function ality anti molecular architecture were prepared and investigated. The advancement of reactions in thermal and microwave fields was monitored in real time by in situ remote near-infrared spectroscopy. The princi pal finding was that the use of microwaves in lieu of thermal heating had no effect on the mechanism or kinetics during the isothermal cure of various epoxies, polyimides and bismaleimides. No ''microwave effec t'' was observed and it was concluded that the claims of ''accelerated kinetics'' in the microwave field are unfounded. However, a compariso n between thermal and microwave cure assumes a whole new dimension whe n the temperature distribution inside the sample is considered, and th at constitutes a scientifically challenging area that warrants further research. (C) 1998 John Wiley & Sons, Ltd.