Study of gamma-ray radiation effects on series of bisphthalonitrile resins: Thermomechanical, mechanical, and thermal properties

The bisphthalonitrile (PN) thermosets series (poly(Baph), poly(Bafph), and poly(Bzph)) were prepared and subjected to 100 and 500 kGy gamma-ray irradiation dose from cobalt-60 (Co-60) as a source. The main objective of this present study was to investigate the effects of gamma irradiation on the chemical structure, thermomechanical, mechanical, and thermal stabilities, which were studied by using a Fourier transform infrared (FTIR), dynamic mechanical analysis, bending test, and thermogravimetric analysis, respectively. The PN resins characteristics bands, namely, nitrile, triazine ring, and phthalocyanine, were not affected on gamma-ray irradiation. However, remarkable changes were observed in the chemical structures of benzene, alkyl and-CF3, which indeed slightly declined the thermal stabilities, thermomechanical and flexural properties. The decrease in properties could be ascribed to the scission of molecular chains and rupture of chemical bonds of PN resin as confirmed by the FTIR. The poly(Bafph) showed a maximum decline in the thermal stabilities and mechanical properties due to the existence of-CF3 in the polymer skeleton, which could not be crosslinked again once scission occurs under radiation. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48313.