Wang X, Hu Y, Song L, Yang HY, Xing WY, Lu HD (2011b) Synthesis and characterization of a DOPO-substitued organophosphorus oligomer and its application in flame retardant epoxy resins. Progress in Organic Coatings 71(1), 72-82. [In English]

Web link: http://dx.doi.org/10.1016/j.porgcoat.2010.12.013

Keywords:

Epoxy resins; Flame retardancy; Organophosphorus oligomer; Thermal; degradation; thermal-degradation; cured products; curing agent; phosphorus; behavior; composites

Abstract: Advanced flame retardant epoxy resins with different contents of poly(DOPO substituted phenyl dimethanol pentaerythritol diphosphonate) (PFR) were prepared. PER was synthesized from the polycondensation of DOPO-disubstituted benzenedimethanol (TDCA-DOPO) with pentaerythritol diphosphonate dichloride (SPDPC). The flame retardancy and thermal stability of the EP/PFR hybrids were investigated by limiting oxygen index (LOI), UL-94 test and thermogravimetric analysis (TGA) in air. LOI values increased from 21.5 for pure EP to 36.0 for phosphorus-containing resins, and UL-94 V-O materials were obtained with the 15 wt% PER. The TGA results indicated that incorporation of PFR significantly enhanced the char yield and the thermal stability of char layer at higher temperature. Differential scanning calorimetry revealed that the EP/PFR composites possessed higher glass transition temperatures than phosphorus-free EP, which was consistent with dynamic mechanical analysis results. The thermal degradation behaviors of the EP/PFR composites were investigated by real time Fourier transform infrared spectra (RTFTIR), thermogravimetric analysis/infrared spectrometry (TG-IR) and direct pyrolysis/mass (DP-MS) analysis. The results suggested that the addition of PER can reduce the release of combustible gas, trap the H and OH radicals by releasing the PO radical and induce the formation of char layer, thus retard the polymer degradation and combustion process. (C) 2011 Elsevier B.V. All rights reserved.