NMR evaluation of montmorillonite's d‐spacings on the formation of phosphocarbonaceous species in intumescent systems

• Published in: Journal of applied polymer science 2019-11, Vol.136 (42), p.n/a
• Main Authors: Pereira da Silva Ribeiro, Simone, Carvalho Martins, Raíssa, Santos Cescon, Leonardo, Rocha de Moura Estevão, Luciana, Chaer Nascimento, Marco Antonio, Veiga Nascimento, Regina Sandra
• Format: Article
• Language: English
• Subjects: Aluminum phosphate; Char formation; intumescent system; Materials science; MNRl; Montmorillonite; NMR; Nuclear magnetic resonance; phosphocarbonaceous species; Polymers
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.48053

ABSTRACT To further investigate the influence of the d‐spacing of montmorillonite types derived from Cloisite Na on the process of the intumescent layer formation, composites of poly(ethylene‐co‐butylacrylate), EBA‐30, with an intumescent formulation consisting of ammonium polyphosphate and pentaerythritol were processed and heated at different temperatures. The residues were analyzed by 13C, 31P, and 27Al solid‐state nuclear magnetic resonance (NMR). 13C NMR peaks in the aromatic range of 100–150 ppm for samples heated at 350 °C suggest that the montmorillonites with smaller d‐spacing (13.5 and 21.8 Å) accounted for the greater amounts of condensed aromatic structures, leading to the char. For d‐spacing of 35 Å, the condensation of the polyaromatic structures occurs more slowly, retarding the char formation. The 27Al NMR peak around −15 ppm for samples heated at 280 °C indicates the destruction of montmorillonite structure, producing aluminophosphate species, meaning that the d‐spacing influences the reactions under this temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48053.