Synthesis of N-ethyl triazine–piperazine copolymer and flame retardancy and water resistance of intumescent flame retardant polypropylene

Abstract

The compounds containing triazine ring are considered as effective charring-foaming agents in intumescent flame retardant (IFR) systems. In this paper, a hydrophobic triazine-containing macromolecule, named as N-ethyl triazine–piperazine copolymer (ETPC), was synthesized through two step reactions, using cyanuric chloride, ethylamine and piperazine as raw materials. The chemical structure, thermal degradation and hydrophobicity of ETPC were characterized by Fourier transform infrared spectroscopy (FTIR), 13C solid-state NMR spectroscopy, elemental analysis, thermogravimetric analysis (TGA) and contact angle measurement. A detailed study of ETPC reveals that ETPC can act as an effective charring and foaming agent in the IFR, due to its high thermal stability, good char formation ability, and excellent hydrophobicity. Moreover, the novel intumescent flame retardant consisting of ETPC, ammonium polyphosphate (APP) and silica was applied to investigate the flame retardancy and water resistance of polypropylene (PP). Based upon Limiting Oxygen Index (LOI), Vertical Burning Test (UL-94), TGA, Cone Calorimeter test (CONE), contact angle, X-ray Photoelectron Spectroscopy (XPS) and the hot water treatment, a comprehensive study indicates the IFR shows very effective flame retardancy and water resistance in PP, and the hot water treatment has a little influence on LOI values, UL-94 ratings, the heat release rate (HRR) and the smoke production rate (SPR). These results prove the ETPC-containing IFR has the potential application value in industry.