Synthesis, spectral and thermal degradation kinetics of novolac resins derived from cardanol

The cardanol formaldehyde resin (CFR) has been synthesized by the condensation of cardanol with formaldehyde (ratio of 1:0.7) in the presence of oxalic acid catalyst. Synthesized CFR was epoxidized using epichlorohydrin (ECH) with 1:10 molar ratio. Cardanol was also directly epoxidized using ECH with the above-mentioned ratio. Synthesized resins have been characterized by Fourier-transform infrared and nuclear magnetic resonance spectroscopic analyses. Thermal properties have been studied by thermogravimetric analysis. Decomposition kinetics have been studied by various kinetic models of the synthesized compounds. In the present study, Horowitz-Metzger, Broido and Coats-Redfern models have been used to calculate the activation energy (E-a), pre-exponential factor (A) and rate constant (K). E-a calculated from all the three models mentioned above was close to each other.