Thermal decomposition products of copol(arylene ether sulfone)s characterized by direct pyrolysis mass spectrometry

• Published in: Polymer degradation and stability 2007-07, Vol.92 (7), p.1304-1315
• Main Authors: Samperi, F, Puglisi, C, Ferreri, T, Messina, R, Cicala, G, Recca, A, Restuccia, C L, Scamporrino, A
• Format: Article
• Language: English
• ISSN: 0141-3910

Pyrolysis products with mass of up to 850 Da were detected by direct pyrolysis mass spectrometric (DPMS) analysis of a series of copoly(arylene ether sulfone)s (PESPPO) synthesized by nucleophilic condensation of either 4,4'-dichlorodiphenylsulfone (CDPS) or 4,4'-bis-(4-chlorophenyl sulfonyl) biphenyl (long chain dichloride, LCDC) with different molar ratios of hydroquinone (HQ) or dihydroxydiphenylsulfone (HDPS). Pyrolysis products retaining the repeating units of the initial copolymers were formed at temperatures ranging from 420 DGC to 470 DGC (near the initial decomposition temperature). At temperatures higher than 450 DGC were observed products containing biphenyl units, formed by the elimination process of SO2 from diphenyl sulfone bridges. Products having biphenyl and dibenzofuran moieties were detected in the mass spectra recorded at temperatures above 550 DGC. These units were formed by loss of hydrogen atom from diphenyl ether bridges. Although the El (18 eV) mass spectra of the pyrolysis products of the samples investigated were very similar, it was found that the relative intensity of some ions reflects the molar composition of the copolymers analysed. Cyclic and linear oligomers with very low molecular mass, present in the crude copolymers, were also detected by DPMS. Thermogravimetric analysis also showed their excellent thermal stability below 400 DGC. It indicates that the copolymers yield a char residue of 40-45% at 800 DGC, which increases with the PPO mole fraction in the samples.