FTIR and GCMS analysis of epoxy resin decomposition products feeding the flame during UL 94 standard flammability test. Application to the understanding of the blowing-out effect in epoxy/polyhedral silsesquioxane formulations

Abstract

A novel method was developed for the sampling of volatiles produces by polymer decomposition during UL94 standard flammability tests, allowing to collect, separate and analyze the precise composition of the fuel mixture feeding the flame in the real flammability tests. The system was validated on epoxy resin/polyhedral oligomeric silsesquioxanes and found extremely informative for the understanding of the flame retardancy mechanisms of POSS, previously referred to as the "blowing-out effect". Collected products were analyzed by infrared spectroscopy and gas chromatography/mass spectroscopy, to identify the gaseous and liquid decomposition products, allowing to depict a comprehensive decomposition pathway for the epoxy resin. Lightweight volatiles, gaseous at room temperature, showed limited differences as a function of DOPO-POSS, whereas mixtures of liquid products evidenced for dramatic changes in the relative concentration as a function of DOPO-POSS. In pristine epoxy resin, the most abundant products were recognized as benzene, phenol, naphthalene and toluene, along with several tens of other aromatic products observed in lower amounts. The presence of DOPO-POSS at low concentration (2.5%) radically changes the composition of the aromatic volatiles mixture, as no significant amount of benzene is produced, while phenol becomes the main product, accounting for about half of the total, isopropyl phenol and bisphenol A, along with several tens of other products in lower concentrations. Such modification of the fuel mixture feeding the flame provided an explanation for the lower flammability of this formulation, as well as for the phenomenology of the blowing out effect.Keywords: epoxy resin decomposition mechanism; DOPO-POSS; blowing-out effect; sampling of volatiles during flame test, fuel mixture in flammability tests

Thermal and Fire Behavior of a Bio-Based Epoxy/Silica Hybrid Cured with Methyl Nadic Anhydride

“…It is reported in the literature that soot includes species with high molecular weight formed in the gas-phase combustion process and residual pyrolyzed fuel particles [40]. During the last steps of the carbonization and gas-phase combustion processes of a DGEBA resin, several phenyl-based compounds (e.g., benzene, naphthalene, anthracene, among a few to mention) are produced at high temperatures (800-1000 • C) [41]. Furan-based epoxy polymers are reported to produce a lower amount of high molecular weight compounds, despite an increased residual char, because of the furan structure that reduces the possible cyclization reactions [23,42,43].…”

Flame retardant and mechanism of vinyl ester resin modified by octaphenyl polyhedral oligomeric silsesquioxane

“…Figure is the FTIR spectra of pure VER and VER‐20OPS at special temperature, and the assignment of the absorption peaks are presented in Table . The major pyrolysis gases detected from the decomposition process of pure VER and VER‐20OPS are phenol derivatives/water (3651 and 3582 cm −1 ), aromatic components (3076, 3032, 1603, 1504, and 1457 cm −1 ), aliphatic components (2973 cm −1 ), and ester/ether components (1249, 1177, 1126, and 988 cm −1 ), which are the decomposition products of molecular segments of VER matrix . As shown in Figure and Table , the evolving gas species for VER‐20OPS are similar to that for pure VER.…”

Study of the epoxy/amine equivalent ratio on thermal properties, cryogenic mechanical properties, and liquid oxygen compatibility of the bisphenol A epoxy resin containing phosphorus

“…Moreover, The C–P bond energy (305 kJ mol −1 ) in the molecular structure of the modified resin was lower than that of the C–C bond energy (332 kJ mol −1 ). 35,36 These two factors made the modified resin decomposed at lower temperature.…”

“…Moreover, as the SR value increased, the excess N element in the curing agent possibly combined with the P element to form a P–N intermediate, which was condensed in the carbon layer, resulting in an increase of carbon residue in the modified resin system. 36…”