Processing and characterization of fire-retardant modified polystyrene/functional graphite composites

In the current endeavor, polystyrene (PS) was first functionalized to get nitro-substituted polystyrene (PS-NO2) and then the matrix was further modified into an amino-functional polystyrene (PS-NH2). Later the effect of addition of acid functional graphite (F-G) on the mechanical, thermal, morphological, and non-flammability properties of composite series (PS/F-G 0.01–0.5, PS-NO2/F-G 0.01–0.5, and PS-NH2/F-G 0.01–0.5) was scrutinized. The composites were prepared using solution processing and melt blending. According to FESEM, the solution mixing of graphite prevented the nano-filler aggregation in the matrix relative to melt-processed hybrids. There was considerable augment in the tensile strength and tensile modulus of solution-processed amino-functional material (32.8–39.6 MPa and 3.8–5.7 GPa, respectively) with functional graphite loading relative to PS/F-G 0.01–0.5 and PS-NO2/F-G 0.01–0.5 prepared. Adding up of F-G also improved the thermal stability of solution-processed composites, and the enhancement was maximum in the case of PS-NH2/F-G 0.01–0.5 with 10% weight loss in the range 446–477 °C. In solution system, cone calorimetry results show a decrease in the PHHR values of the composites relative to pure PS and nitro-functional matrix. PS-NH2/F-G 0.5 had PHHR value of 462 kW/m2, and the reduction of HRR values was also escorted by decrease in ignition time. Thermal, mechanical, and non-flammability results of solution-processed systems were found to be enhanced compared with melt-blended system depicting the advantage of the technique used.