Intumescent flame retardancy of a DGEBA epoxy resin based on 5,10-dihydro-phenophosphazine-10-oxide

Abstract

5,10-Dihydro-phenophosphazine-10-oxide(DPPA) served as a co-curing agent of 4, 4'-diaminodiphenylmethane for the curing reaction of bisphenol A diglycidyl ether (DGEBA) epoxy resin (EP). 1 H NHR spectrum tracking the reaction process of DPPA with DGEBA revealed that P-H bond of DPPA had the higher reactivity than its N-H bond for reacting with epoxy group. DPPA could promote the curing reaction of DDM with DGEBA. DPPA endowed epoxy resin with high flameretardant efficiency due to the unique combination of phosphorus and nitrogen in the phenophosphazine ring. The cured epoxy resin could pass V-0 rating of UL-94 test with limiting oxgen index (LOI) of 33.6% at only 2.5 wt% DPPA. The reduced peak heat release rate and total heat release, and increased char yield further verified the excellent flame retardancy for EP. Flame-retardant mechanism of the epoxy resin was investigated by thermogravimetry-fourier transform infrared spectrometry (TG-FTIR), scanning electron microscopy, element analysis and FTIR spectrometry. The results indicated that DPPA catalyzed epoxy resin matrix to form the rigid intumescent char and to generate the blowing-out effect.

Flame‐Retarded Epoxy Resins with a Curing Agent of DOPO‐Triazine Based Anhydride

“…Owing to the remarkable environmental‐friendly feature, the nitrogen‐containing flame retardant has been progressively explored. What's more interesting, is that such element could integrate co‐effect with phosphorus one, thus decreasing the sum quantity of the flame retardant and advancing the comprehensive properties of the flame‐retarded epoxy thermosets . Triazine ring is capable for supplying the nitrogen source and increases the thermal stability of polymer matrix through providing the rigid structure.…”

“…What's more interesting, is that such element could integrate co-effect with phosphorus one, thus decreasing the sum quantity of the fl ame retardant and advancing the comprehensive properties of the fl ame-retarded epoxy thermosets. [15][16][17] Triazine ring is capable for supplying the nitrogen source and increases the thermal stability of polymer matrix through providing the rigid structure. Moreover, the concomitance of triazine and DOPO structure for fl ame-retarding DGEBAbased epoxy resins cured with aromatic amine hardeners seems promising as they could acquire the great fl ame retardancy with relatively low phosphorus content and well-maintained T g value.…”

Intrinsic Flame-Retardant and Thermally Stable Epoxy Endowed by a Highly Efficient, Multifunctional Curing Agent

“…The introduction of DOPO derivatives drops T 5% by 25–30 °C for the flame-retardant DGEBA/DDM [36,37]. As in our previous study using DPPA, the reduction of T 5% is adequately suppressed but still over 10 °C [26]. In addition to the superior efficiency in the flame-retardant aspect, where a smaller amount of HB-DPPA is needed for passing UL-94 test, the inclusion of an aromatic benzene ring in the HB-DPPA molecule provides a more rigid structure to the polymer network.…”

The flame retardancy and rheological properties of PA6/MCA modified by DOPO-based chain extender

“…The increase in melt viscosity restrains the instantaneous emissions of inert gas and combustible gas, so that they would accumulate and generate more internal pressure to perforate the surface and gush inside out, and eventually extinguish the ame on burning drip. 18 Cone calorimeter measurement is an effective method to analyze the combustion behavior of material under sustained external force. The results of cone calorimeter test, including time to ignition (TTI), heat release rate (HRR), rate of smoke release (RSR), total heat release (THR), total smoke release (TSR) and residual mass, are listed in Table 2.…”