Synthesis of tris(phenoxy)trifluorocyclotriphosphazenes and study of its effects on the flammable, thermal, optical, and mechanical properties of bisphenol-A polycarbonate

Abstract

A flame-retardant tris(phenoxy)trifluorocyclotriphosphazenes, 2,4,6-N3P3(OPh)3F3 (TCTP) containing phenoxyl, fluorine, and cyclotriphosphazene ring was synthesized from hexachlorocyclotriphosphazene and added to polycarbonate (PC) to improve flame retardancy. Its chemical structure was confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance. The synthesis of TCTP was designed to improve the flame retardancy of PC without harming PC excellent optical and mechanical performances. The flame retardancy and thermal degradation behavior of PC/TCTP composites were investigated with the limiting oxygen index (LOI), UL-94 vertical burning test, microscale combustion calorimeter, thermogravimetric analysis, and differential scanning calorimetry. Scanning electron microscopy (SEM) analyses and FTIR spectrophotometer were brought together to study the structure of residual char. The optical and mechanical properties of PC were also taken into consideration at the same time. When 10 % TCTP was incorporated, the LOI of composite achieved the maximum of 40 %, and class V-0 of UL-94 test was passed. The phenomena of SEM and FTIR stated that there was interaction between PC and TCTP to form new stable film in mid of residual char. Light transmittance, tensile, and flexural strength of PC/TCTP systems were improved at different levels.