Allyl phenolic-phthalonitrile resins with tunable properties: Curing, processability and thermal stability

In order to modify the curing procedure and broaden the processing windows of phthalonitrile, allyl phenolic moieties were incorporated into phthalonitrile resins at different ratios through sequential nucleophilic substitution reaction. The curing behavior, along with the reaction between allyl and nitrile groups, were investigated in detail. The curing kinetic equations were derived by Sestak-Berggren (SB) model. The rheological tests showed that the minimum viscosity significantly decreased from 15 Pa.s to less than 1 Pas and the processing windows varied from 24 to 89 degrees C with the allylation degree increasing. The novel oligomers demonstrated a maximum T-5% of 494 degrees C, 74% char yield at 1000 degrees C and a high glass transition temperature exceeding 400 degrees C. The correlation between allylation degree and concerned parameters, including curing temperatures, processing windows and T-5% was established, which allows for tailoring polymer structure for various applications.