Novel intumescent flame retardants: synthesis and application in polycarbonate

Novel phosphorus-containing and nitrogen-containing intumescent flame retardants, bis-aminobenzyl spirocylic pentaerythritol bisphosphonate (BASPB) and arylene-N,N-bis(2,2-dimethyl-1,3-propanediol phosphoramidate) (ABDPP), were synthesized, and their structures were characterized with Fourier transform infrared spectroscopy and H-1 and P-31 nuclear magnetic resonance. The phosphorus compounds were used to impart flame retardancy to polycarbonate (PC). Combustion behaviors and thermal degradation properties of the flame-retarded-PC composites were assayed by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimeter test, and thermogravimetric analysis. PC/5wt.% BASPB and PC/5wt.% ABDPP composites passed UL-94 V-0 rating; their LOI values were 35.5% and 34.7%, respectively. Scanning electron microscopy revealed that the char properties had crucial effects on the flame retardancy. The mechanical properties and water resistance of the PC/BASPB and PC/ABDPP composites were also measured. After water resistance test, PC/5wt.% BASPB and PC/5wt.% ABDPP composites kept V-0 rating, and the mass loss was only 1.0%. Copyright (c) 2012 John Wiley & Sons, Ltd.