Evaluation of curing kinetics of silicon‐substituted phthalonitrile resin by model‐based and iso‐conversional methods

Abstract The curing of 4,4′‐(4,4′‐(dimethylsilanediyl)bis(4,1‐phenylene)bis(oxy)) diphthalonitrile (SiPN) by meta ‐aminophenoxydiphenylsulfone as a curing catalyst is investigated using differential scanning calorimetry (DSC) at ramp rates of 5, 10, 15, and 20 K min −1 . The kinetic parameters of the curing reaction, i.e., activation energy ( E a ), reaction order ( n ), reaction rate constant ( k ), and Arrhenius factor ( A ), were calculated from non‐isothermal kinetic methods. E a for SiPN resin was found to be ca 74.89 and 66.78 kJ mol −1 via Ozawa and Kissinger methods, respectively. The reaction order was found to be 0.86, as calculated from Crane's equation. The Kissinger method was also used to estimate the frequency or A value of ca 2.26 × 10 8 and ultimately the rate constant at various peak heat release temperatures ( T p ) to enumerate the rate equation for the SiPN curing reaction. Isothermal DSC scanning at 170, 180, 190, and 200 °C was performed to evaluate the relationship between rate and degree of curing, which indicated that at 30–40% conversion, maximum rate of curing was observed. The study also revealed that E a and A are related to the degree of curing ( α ), which is in accordance with known literature. To obtain the exact curing profile, the extrapolation method was adopted which suggested that in order to achieve maximum curing, the sample should be gradually heated up to 467.5 K and held at that temperature followed by heating up to 485.5 K and subsequently up to 526.5 K. © 2025 Society of Chemical Industry.