The Flame Retardant Group-Synergistic-Effect of a Phosphaphenanthrene and Triazine Double-Group Compound in Epoxy Resin

A flame retardant tri-(phosphaphenanthrene-(hydroxyl-methylene)-phenoxyl)-1, 3, 5-triazine (Trif-DOPO) and its control samples are incorporated into diglycidyl ether of bisphenol-A (DGEBA) and 4, 4-diamino-diphenyl sulfone (DDS) to prepare flame retardant thermosets, respectively. According to the results of limited oxygen index (LOI), UL94 vertical burning test and cone calorimeter test, the Trif-DOPO/DGEBA/DDS thermoset with 1.2 wt % phosphorus possesses the LOI value of 36% and UL94 V-0 flammability rating, and Trif-DOPO can decrease the peak of heat release rate (pk-HRR) and reduce the total heat release (THR) of thermosets. All these prove better flame retardant performance of Trif-DOPO than that of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO). The residue photos of thermosets after cone calorimetry test disclose that Trif-DOPO can promote the formation of thick and tough melting char layer for combined action of the flame retardant groups of Trif-DOPO. The results from thermo gravimetric analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry(Py-GC/MS) show that the groups in Trif-DOPO can be decomposed and produce PO2 fragments, phosphaphenanthrene and phenoxy fragments, which can jointly quench the free radical chain reaction during combustion. Therefore, the excellent flame retardancy of Trif-DOPO is attributed to its flame retardant group-synergic-effect. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39709.