C. Ma, B. Yu, N. N. Hong, Y. Pan, W. Z. Hu and Y. Hu (2016) Facile Synthesis of a Highly Efficient, Halogen-Free, and Intumescent Flame Retardant for Epoxy Resins: Thermal Properties, Combustion Behaviors, and Flame-Retardant Mechanisms. Journal/Industrial &, Engineering Chemistry Research 55 10868-10879. [In English]
Web link: http://dx.doi.org/10.1021/acs.iecr.6b01899
Keywords: ,GLASS-TRANSITION TEMPERATURES, PHOSPHINE OXIDE, CURING AGENT, THERMOGRAVIMETRIC ANALYSIS, PHOSPHORUS-CONTENT, DIGLYCIDYL ETHER, HIGH-PERFORMANCE, CURED PRODUCTS, NOVOLAC RESINS, HEXAPHENOXYCYCLOTRIPHOSPHAZENE

Abstract: A novel branched poly(phosphonamidate-phosphonate) (BPPAPO) oligomer was synthesized from the polycondensation of phenylphosphonic dichloride and tri-hydroxymethylphosphine oxide followed by end-capping with aniline in a one-pot synthesis. BPPAPO exhibited excellent flame-retardant efficiency in epoxy resins (EP). With only 5.0 wt % loading, the EP composite reached UL-94 V-0 rating with a limiting oxygen index (LOI) value of 35.5%. BPPAPO catalyzed the early degradation of EP and promoted the formation of more char residue. Glass transition temperatures were partially lowered. When 7.5 wt % BPPAPO was incorporated, the peak heat release rate and total heat release were decreased by 66.2% and 37.3%, respectively, with a delayed ignition and the formation of a highly intumescent char residue. Combination of gas-phase and condensed-phase flame-retardant mechanisms was verified.