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

The curing reactions of benzoxazine precursors based on bisphenol A an d 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 t he excellent heat resistance and fire and smoke properties of these re sins. This new type of phenolic material cures via a ring-opening mech anism that does not produce any condensation or other reaction by-prod ucts. Phenol is not used as raw material, which reduces considerably t he environmental and health risks. According to differential scanning calorimetry (d.s.c.), the curing of benzoxazine precursors is an autoc atalysed reaction until vitrification is reached, and diffusion begins to control the curing process afterwards. Isothermal and non-isotherm al d.s.c. tests are performed. Calculations of the activation energy a nd the overall reaction order are made by various procedures. The vitr ification times and the kinetic rate constants are also calculated.