Curing Kinetics of Hydrazide‐Substituted Phthalonitrile Resin (HYZ‐PN) via Model‐Based and Model‐Free Kinetic (MFK) Methods

ABSTRACT The curing kinetics of (3,4‐dicyano‐ N '‐(3,4‐dicyanobenzoyl) benzo‐hydrazide) (HYZ‐PN) with meta‐aminophenoxydiphenylsulfone (m‐BAPS) were investigated using nonisothermal differential‐scanning‐calorimetry (DSC) at heating rates of 5–20 K/min. Kinetic parameters were determined via model‐based and model‐free kinetics (MFK) methods. The average activation energy ( E α ), calculated using Ozawa and Kissinger methods, was ∼140.16 kJ/mol. A reaction order “ n ” of ∼0.967, determined from Crane's equation, indicates an autocatalytic curing mechanism. The frequency factor ( A = ∼ 6.5 × 10 11 sec −1 ) is consistent with chemically controlled solid‐state‐polymerization using model‐fitting methods. E α and A were also further evaluated as a function of the degree of cure ( α ) using MFK methods. To achieve maximum conversion, an optimized curing profile was established; a hold at 540 K, followed by successive heating to 558 and 590 K. Experimental cure rates showed good agreement with theoretical estimates for heating rates upto 15 K/min.