Comparison of thermal degradation characteristics of poly(arylene sulfone)s using thermogravimetric analysis/mass spectrometry

Abstract

Thermal degradation of poly(arylene sulfone)s had been studied by the combination of thermogravimetric analysis/mass spectrometry (TG/MS) with pyrolysis/ gas chromatography/mass spectrometry (Py-GC/MS) techniques. Through these two methods, the pyrolysates from poly(ether sulfone) (PES) and polysulfone (PSF) were identified in 11 and 21 sets of evolution curves, respectively, from room temperature to 900°C. Among these pyrolysates, 12 products from PES and 25 products from PSF were obtained. The major mechanism for both PES and PSF was one-stage pyrolysis involving main chain random scission and carbonization with evolution of SO 2 and phenol as major products. Although the initial thermal stability of PES was lower than that of PSF, the formation of sulfide groups in the condensed phase from PES, through reduction of sulfone group by hydrogen radicals, increased the fire retardation behavior of PES. In PES, the ether and sulfone groups showed similar thermal stability. The thermal stability of functional groups in PSF were in the order of sulfone Ͻ ether Ͻ isopropylidene group. The scission of the ether group in PSF, with evolution of phenol as the major product, reached maximum evolution amount at the temperature of the maximum thermogravimetry loss of TG (T max ). The scission of isopropylidene groups at high temperature (Ͼ580°C) evolved higher mass derivatives that lower the fire retardancy of PSF. By using a simplified kinetic model, PES showed maximum activation energy with a conversion ratio of 0.2-0.3, which implies a high fire retardant effect of sulfide formation in PES. A comparative study with the proposed model and experimental data showed the theoretical pyrolysis curves to be in agreement with the experimental curves for PES and PSF pyrolysis, respectively.

Highly permeable and mechanically robust silicon carbide hollow fiber membranes

“…A second mass loss step is recorded at intermediate temperatures (450-650 1C), where SO 2 , CO, CO 2 and water are the main gases emitted, followed by a minor mass loss concurring with release of methane, CO and CO 2 at 750 1C. This observed decomposition process matches closely to the reported decomposition of PES under an argon atmosphere[27][28][29]Photo of, from left to right, a green, sintered at 1500 1C, sintered at 1790 1C, sintered fiber 2075 1C (A), and cross-sectional images of a green (B), a green (C), 1500-Ar (D), 1790-Ar (E) and 2075-Ar (F) sintered fibers.…”

IR laser ablative degradation of poly(phenylene ether-sulfone): Deposition of films containing ether, sulfone, sulfoxide and sulfide groups

“…The detected gaseous products and the spectral properties of the deposited films show that the IR laser-induced and the conventional degradation [6,7,9,10] of PES remarkably differs in products. The latter yields diphenyl compounds (Ph 2 , Ph 2 O, Ph 2 S, PhSO 2 Ph), SO 2 and phenol and a carbonaceous char.…”

“…The latter yields diphenyl compounds (Ph 2 , Ph 2 O, Ph 2 S, PhSO 2 Ph), SO 2 and phenol and a carbonaceous char. It is a one-stage mainchain random scission and carbonisation and involves four major paths [6,9,10]. These are (i) the splitting of the weakest C-S bond allowing release of gaseous SO 2 , (ii) the splitting of the C-O bond enabling elimination of phenol that remains partly retained in the solid residue, (iii) the combination of phenyl radicals to biphenyl yielding biphenylene units and (iv) a complete hydrogenation of sulfone groups to aromatic sulfides.…”

“…Diphenyl sulfone, diphenyl ether and diphenyl are the decomposition products at lower (250-400 C) temperatures [7]. At higher temperatures [6,7,9,10], thermal decomposition of PES occurs as a one-stage main-chain random scission and carbonisation, yielding SO 2 , phenol (major products), diphenyl sulfone, diphenyl ether and a char. The char was believed (but not proved) to have a polyphenylene structure when formed at 535-580 C and a cross-linked structure when formed at above 950 C. In these studies, polymer degradation occurs through heat transfer from heating elements or reactor walls; it is controlled thermodynamically and possibly assisted by heterogeneous catalysis.…”

“…Thermal behaviour of the simplest member of these polymers, poly(1,4-(phenylene ether-sulfone)) (PES) has been intensely studied applying pyrolysis and EPR spectroscopy [6] thermogravimetry [7,8] and combination of thermogravimetry or pyrolysis with mass spectrometry and gas chromatography [9][10][11]. Diphenyl sulfone, diphenyl ether and diphenyl are the decomposition products at lower (250-400 C) temperatures [7].…”