Synthesis of a heat-resistant DOPO derivative and its application as flame-retardant in engineering plastics

A star-shaped DOPO derivative (GL-3DOPO, P content 10.8 wt %) was synthesized through a two-step reaction involving glycerol, acryloyl chloride, and DOPO. The derivative demonstrated a great improvement of thermal decomposition temperature increased to 360 degrees C from 194 degrees C (under N-2 atmosphere), promoting its application in thermoplastics of high processing temperature. When blended with engineering plastics including PET, PBT, PC, PA6, and PA66 at a GL-3DOPO loading of 25 wt %, all the compounds reached the UL94 V-0 level and increased limit oxygen index (LOI). In PET system, LOI raised from 22.8% to 35.4% with P 2.5 wt % and passed the V-0 test with only 0.8 P wt %. Compact char layers were found in the PET system after LOI test, suggesting that GL-3DOPO acted both in gas and condensed-phase mode. All results indicated that GL-3DOPO could be a potential flame-retardant for engineering plastics. (C) 2017 Wiley Periodicals, Inc. J. Appl. Polym.