Phosphazene-triazine cyclomatrix network polymers: some aspects of synthesis, thermal- and flame-retardant characteristics

✍ Scribed by Mathew, Dona; Nair, C?P Reghunadhan; Ninan, K?N

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 157 KB
• Volume: 49
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(200001)49:1<48::aid-pi309>3.0.co;2-m

✦ Synopsis

Hydroxy phenyl-substituted cyclotriphosphazenes were synthesized by reacting hexachlorocyclotriphosphazene with sodium phenolate and monosodium bisphenolate. The derivatives, consisting of a mixture of multi-substituted and partly chain-extended cyclophosphazenes, with overall functionality close to the targeted values, were transformed into the cyanatophenyl derivative. Thermal curing of the latter gave phosphazene±triazine cyclomatrix network polymers with varying ratios of phosphazene and triazine rings in the matrix. Although they manifested diminished T g , the cured polymers were more thermally stable and provided higher char residue in comparison to the polycyanurate derived from bisphenol-A dicyanate. The activation energies for thermal decomposition of the cyclomatrix networks increased with both phosphazene content and crosslink density, and showed a direct relationship with their thermal stability. The presence of phosphazene was conducive for enhancing the ¯ame retardancy of the network. The ¯ame retardancy improved with increase in crosslink density and char-yielding property of the polymer, which implied that the ¯ame-retardant action was operative in the condensed phase.