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Abstract A phosphorus‐containing resorcinol‐substituted phthalonitrile (PRcPN) resin and its laminate composite have been examined in this work along with their synthesis, rheological characteristics and viscoelastic behavior. With a natural tack at 40–50 °C, the resin has demonstrated an exceptional shelf‐life under ambient settings (>3 years). Additionally, the resin has shown broad processing and curing windows of around 237 and 80 °C, respectively, according to differential scanning calorimetry (DSC). In DSC examination, the fully cured resin showed no glass transition ( T g ) up to 400 °C. During rheological testing, the resin's gelation temperature was determined to be approximately 313 °C, which resulted in a large processing window of approximately 263 °C with low melt viscosity in the range of approximately 0.5–5 Pa s. The resin is a good option for laminate composites because of its low viscosity. According to thermogravimetric analysis measurements, the cured thermoset polymer's thermal and oxidative stability were around 479 and 380 °C (i.e. 5 wt% degradation), respectively. The cured polymer's fire‐retardant character was demonstrated by the limiting oxygen index value, which was around 49.5% and it was estimated by the empirical relationship of the van Krevelen equation. The crosslinking density has been found to be 2.3 × 10 −3 mol cm −3 . Using the vacuum‐assisted resin transfer molding process, the CFR‐PN laminate has been fabricated while keeping the reinforcement to matrix ratio at 58:42 (w/w). The T g value of laminate sheet after post‐curing was found to be around 510 °C (tan δ peak) via dynamic mechanical analysis. Additionally, the cast sheet displayed T g at about 350 °C. The activation energy was determined using Broido's integrated approach, and the cured thermoset exhibits two‐step deterioration. These high thermal parameter values suggest that the resin may find usage for high‐temperature aviation applications. © 2025 Society of Chemical Industry.
Banshiwal et al. (Fri,) studied this question.