Preparation and thermal properties of flame retardant phthalonitrile/epoxy blends

The blends were successfully prepared by the copolymerization of 2,2-bis [4-(3, 4-dicyanophenoxy) phenyl] propane (BAPh) and epoxy resins E-44 (EP) in the presence of 4,4′-diaminodiphenyl sulfone (DDS) as curing additive. With the loading of BAPh in blends increasing from 10% to 50%, the excellent flame retardancy properties of the copolymers with the weight ratio of 20:80 of BAPh/EP achieved over 30 according to the limiting oxygen index test (LOI) values and V-0 grade of UL-94 measurement compared with the pure EP. The temperatures at weight loss 5% (T5%) of the pure EP were improved 16.4°C in nitrogen and 64.6°C in air when the ratio was 20:80. In addition, the gelation time was shortened to 3 min when the prepolymerization temperature was 190°C