Preparation and properties of halogen-free flame-retarded phthalonitrile-epoxy blends

Halogen-free flame-retarded blends composed of 2,2-bis[4-(3,4-dicyanophenoxy) phenyl] propane (BAPh) and epoxy resin E-44 (EP) were successfully prepared with 4,4'-diaminodiphenyl sulfone as a curing additive. The structure of the copolymers was characterized by Fourier transform infrared spectroscopy, which showed that epoxy groups, a phthalocyanine ring, and a triazine ring existed. The limiting oxygen index values were over 30, and the UL-94 rating reached V-0 for the 20 : 80 (w/w) BAPh/EP copolymers. Differential scanning calorimetry and dynamic rheological analysis were employed to study the curing reaction behaviors of the phthalonitrile/epoxy blends. Also, the gelation time was shortened to 3 min when the prepolymerization temperature was 190 degrees C. Thermogravimetric analysis showed that the thermal decomposition of the phthalonitrile/epoxy copolymers significantly improved with increasing BAPh content. The flexible strength of the 20:80 copolymers reached 149.5 MPa, which enhanced by 40 MPa compared to pure EP. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 3580-3586, 2012