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Chemistry of char forming mechanism of spirophosphates

Author Affiliations

  • 1Deparment of Chemistry, Nadar Saraswathi College of Engineering & Technology, Vadapudupatti, Theni 625531, India
  • 2Safety Engineering Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, India
  • 3Dept. of Polymer Technology, Kamaraj College of Engineering and Technology (Autonomous), S.P.G.C. Nagar, K.Vellakulam 625701, India
  • 4Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal

Res. J. Material Sci., Volume 10, Issue (1), Pages 1-8, February,16 (2022)


The spirophosphates are an important class of intumescent system, which produces effective voluminous char to protect the underlying materials. The char developed during the intumescent process play vital role in the flame retardant mechanism. Six different spirophosphates were synthesized, by treating spirodichlorodiphosphate with phenol, cresols (o-, m- and p- isomers), di- and tri-methyl phenols and their char forming chemistry were investigated. The residual char acquired by subjecting the synthesized intumescent materials to isothermal pyrolysis at 300°C, 400°C, 500°C and 600°C were investigated by FTIR and SEM analysis. FTIR analysis indicated the formation of structurally similar chemical entities from these intumescent materials when they were subjected to isothermal pyrolysis at different temperatures. The formation of phosphate rich carbonaceous complexes was identified. SEM analysis showed that the char produced was having considerably a compact structure.


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