Thermal characterization of the phosphorus-containing sulfone-modified epoxy resins by thermogravimetric analysis and direct pyrolysis-GC/MS measurement on the thermally degradative volatiles

Thermal degradations of sulfone-containing epoxy resins modified with a linear phenylphosphonate (P2-EBPS) or a tribranched phosphate (P3-EBPS) in the main chains were conducted by thermogravimetric analysis. Thermal degradative volatiles (TDVs) were analyzed by direct pyrolysis (DP)-GC/MS spectrometer in the instantaneous pyrolytic condition at 900 degrees C. A detailed study on the formation of the degradative volatiles was conducted by stepwise pyrolysis. Individual TDVs were separated through the GC column and detected by the mass detector. Results indicate that the degradation of the phosphated epoxy matrix started from the crosslinked aliphatic diglycidyl ether segment and released the phenol and its derivatives as the main aromatic TDVs. The organophosphorus group of the modified epoxy specimens must first be transformed into inorganic phosphate near 450 degrees C at 10 degrees C/ms, before the shielding effect can be effective. The phosphated P3-EBPS has better thermal properties than the phenylphosphonated P2-EBPS copolymer. (C) 1999 Elsevier Science Ltd. All rights reserved.