New nitrogen-rich flame retardant based on conductive poly(aniline-co-melamine)

摘要

In the present work, a new copolymer was synthesized using aniline and melamine as a comonomer in order to increase the content of nitrogen in the final copolymer. The copolymer was synthesized via chemical oxidative polymerization of aniline and melamine, at different ratios, in the presence of ammonium peroxydisulfate (APS) as an oxidant. The obtained copolymers were characterized by Fourier-Transform Infrared spectroscopy (FTIR), Ultraviolet-visible (UV-Vis) spectroscopy, and Energy-dispersive X-ray (EDX). The solubility of the prepared copolymers was tested in various common organic solvents and the results showed that their solubility was better than polyaniline (PANI) in polar aprotic solvents. The elemental analysis revealed high content of nitrogen, around 72 wt% in one copolymer, against 34.6 wt% in the case of polyaniline homopolymer. The average conductivity of the PANI was 1.02 x 10(-1) S/cm while it was between 6.1 x 10(-4) S/cm and 2.9 x 10(-2) S/cm for copolymers. Thermal degradation and flammability were investigated using Thermogravimetric analysis (TGA) and Pyrolysis Combustion Flow Calorimeter (PCFC), respectively. TGA results showed that the onset temperature of decomposition was significantly increased for all copolymers in respect to polyaniline. Moreover, PCFC tests revealed very low flammability character of the synthesized copolymers demonstrated by the Total Heat Release (THR) between 3 and 5 kJ/g. The elemental analysis of the remained char residue at the end of TGA showed that even at 900 degrees C, the high amount of nitrogen remained in the condensed phase for two copolymers.