Structural basis for intumescence– study of model compounds containing spiro phosphorus moiety and polymers containing such units

Structural Basis for Intumescence—Part II: Synthesis and Characterization of Intumescent Polymers Containing Spirophosphorus Moiety in the Backbone

“…The spiro compound (Scheme 1) was synthesized [17,[19][20][21][22][23] as detailed below. Pentaerythritol (2 mol, 272.3 g) and phosphorus oxychloride (4.3 mol, 660 g) were placed in a 3 L round bottom flask under reflux, protected from atmospheric air.…”

“…The actual spectrum shows a multiplet in the region 3-4 ppm. The different spatial orientation of the methylene protons [17] and their interactions may be the reason for this multiplet. All the polymers show the signal due to this proton in slightly up-field region compared to the spiro.…”

“…The mechanism of intumescent action of the model compounds 3,9-dichloro-2,4,8,10-tetraoxo-3,9-diphosphaspiro- [5,5]-undecane-3,9-dioxide (Spiro) and 3,9-dihydroxy-2,4,8,10-tetraoxo-3,9-diphosphaspiro- [5,5]undecane-3,9-dioxide derived from pentaerythritol and phosphorus oxychloride is studied in detail using DTA, Thermal Volatilization Analysis (TVA) [12][13][14][15][16][17] and pyrolysis-mass spectrometry techniques [17] . 3,9-disubstituted-2,4,8,10-tetraoxo-3,9-diphosphasipro- [5,5]-undecane-3, 9-dioxide containing compounds show intumescent flameretardant behavior since the structural entity is having both acid and carbon sources in single moiety.…”

Structural Basis for Intumescence – Part III – Thermal Degradation Study of Intumescent Polymers Containing Spirophosphorus Moiety in the Backbone

“…The synthesis of spiro and the aromatic polyphosphates based on the spiro are detailed elsewhere [20,21] . The repeat unit of the polymers with code is presented in Table 1.…”

“…Examples of the polyol, catalyst and nitrogen source are dipentaerythritol, ammonium polyphosphate and melamine. Based on this general concept, 3,9-dichloro-2,4, 8,10-tetraoxo-3,9-disposphaspiro-[5.5]-undecane-3,9-dioxide (spiro) has been synthesized and its intumescent properties have been investigated and reported [20] . Using this compound as one of the reactive monomers, a family of aromatic spirophosphates was synthesized using various dihydric phenols like resorcinol, hydroquinone, 4,4 0 -dihydroxydiphenyl, bisphenol-A and fluorenedicarbinol as the other monomer.…”