POSS-modified ammonium polyphosphate for improving flame retardant of epoxy resins

An innovative phosphorus-silicone flame retardant (KAPP-OGPOSS) was prepared by grafting octa (propyl glycidyl ether) polyhedral oligomeric silsesquioxane (OGPOSS) on ammonium polyphosphate (APP) through silane coupling agent (KH-550). The chemical structure, morphology, flame retardancy, and mechanism of the obtained materials were comprehensively investigated. TG results demonstrated that EP with 15 wt% KAPP-OGPOSS produced a char residue of 42.6% at 700 degrees C, which is three times that of pure EP. The flame retardant tests showed that the limiting oxygen index value of EP/15 wt% KAPP-OGPOSS was 30.6% (67.7% higher than that of neat EP) and its UL-94 grade reached to V-0 rating. Cone calorimeter testing indicated that the incorporation of 15 wt% KAPP-OGPOSS to EP significantly reduced heat, smoke, CO, and CO2 release by 79%, 83%, 80%, and 82.5%, respectively. The modification of APP with OGPOSS was also beneficial for the improvement of the char yield and density of char. A flame retardant mechanism was revealed according to the investigation into the char residue. This modified approach provided an innovative yet practical means of enhancing the flame retardant properties of EP.

Automated summary

An innovative phosphorus-silicone flame retardant (KAPP-OGPOSS) was prepared by grafting OGPOSS onto APP, which significantly enhanced the flame retardant properties of EP, increasing char residue and density.