CURING KINETICS OF A NEW BENZOXAZINE-BASED PHENOLIC RESIN BY DIFFERENTIAL SCANNING CALORIMETRY

The curing reactions of benzoxazine precursors based on bisphenol A and aniline are studied to determine the feasibility of processing them into final phenolic parts. Benzoxazine precursors are able to overcome most of the shortcomings of traditional phenolic resins, and retain the excellent heat resistance and fire and smoke properties of these resins. This new type of phenolic material cures via a ring-opening mechanism that does not produce any condensation or other reaction by-products. Phenol is not used as raw material, which reduces considerably the environmental and health risks. According to differential scanning calorimetry (d.s.c.), the curing of benzoxazine precursors is an autocatalysed reaction until vitrification is reached, and diffusion begins to control the curing process afterwards. Isothermal and non-isothermal d.s.c. tests are performed. Calculations of the activation energy and the overall reaction order are made by various procedures. The vitrification times and the kinetic rate constants are also calculated.