Understanding the curing kinetics and rheological behaviour of a new benzoxazine resin for carbon fibre composites

The curing kinetics and viscoelastic properties of a benzoxazine resin intended for liquid resin infusion and resin transfer moulding processes was investigated by differential scanning calorimetry (DSC) and rheological experiments. An autocatalytic kinetic model was proposed and all kinetic parameters including reactions orders and activation energy were determined. The curing kinetic equation obtained by linear model-fitting of non-isothermal experiments matched reasonably well with the experimental results from both non-isothermal and isothermal tests. The evolution of viscoelastic properties, such as storage modulus (G′), loss modulus (G″) and complex viscosity (IŋI*) was recorded during the curing reaction. Gelation times at several isothermal temperatures between 170 and 210 °C were obtained and the activation energies for curing and gelation were calculated. Finally, quasi-isothermal DSC experiments were carried out in order to obtain the vitrification times, using the inflexion point of the reversing heat capacity (Cp-rev).