Synergistic Effect Between a Triazine-Based Macromolecule and Melamine Pyrophosphate in Flame Retardant Polypropylene

A novel charring agent, namely triazine-based macromolecule (TBM), was synthesized via solution polycondensation of cyanuric chloride, ethanolamine, and diethylenetriamine. The prepared charring agent possessed little water solubility and superior char-forming ability, and it showed good synergistic effects with melamine pyrophosphate (MPP) in flame retardant polypropylene (PP). When the content of MPP was 16.7 wt% and TBM was 8.3 wt%, the limiting oxygen index (LOI) of the PP/MPP/TBM composite could reach 31.0%, and a UL-94 V-0 rating was achieved based on the vertical burning test. Furthermore, the composite exhibited an outstanding water resistance that it could still obtain a V-0 rating after soaking in hot water for 168 h. The cone calorimetry test (CCT) results demonstrated that the peak heat release rate (PHRR), the total heat release (THR) and mass lose rate (MLR) of the composite were decreased significantly in comparison with those of pure PP. The thermogravimetric analysis (TGA), thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR), and scanning electron microscopy-energy dispersive spectra (SEM-EDS) results revealed that the efficient flame retardancy of MPP/TBM was mainly attributed to the formation of a compact and thermostable intumescent char on underlying materials during a fire. POLYM. COMPOS., 33: 35-43, 2012. (C) 2011 Society of Plastics Engineers