Thermal degradation kinetics of phenol—crotonaldehyde resins

A series of base catalysed phenol-crotonaldehyde and phenol-formaldehyde resins of different mole ratios were synthesized and their thermal behaviour was studied. The non-isothermal procedures of Coats-Redfern and Horowitz-Mitzger were applied to study the thermal degradation kinetics of these resins in air. The softening temperature of phenol-crotonaldehyde resins after curing was found to be in the range of 143–158 °C and phenol-formaldehyde resins of similar type exhibited infusible thermoset behaviour. Phenol-crotonaldehyde resins in the presence of a cross-linking agent, after curing at elevated temperatures, yielded infusible thermosets. The initial, final, 10% and 20% degradation temperatures (DT) of cured phenol-crotonaldehyde resins were higher than those observed for uncured as well as cured phenol-formaldehyde resins. The estimated activation energy for the cured phenol-crotonaldehyde resins is higher (102.5 kJ mole −1) compared to cured phenol-formaldehyde resins (57.3 kJ mole −1).