Phosphorus-containing polymers. thermal degradation

It has been observed that all the phenoxaphosphine ring-containing polymers have excellent thermal stability and show better heat resistance than open-chain phosphorus containing polymers. The phenoxaphosphine polymers containing aromatic rings in the backbone show little degradation below 400°C in air. 

Carja lonela-Daniela, Serbezeanu Diana, Lisa Gabriela, Vlad-Bubulac Tachita, and Hamciuc Corneliu. Thermal degradation and kinetic studies of new flame-retardant phosphorus-containing polymers with liquid crystalline properties. Int. J. Polym. Anal. Charact. 19 no. 4 (2014a) 372-382. 

Gentilhomme A, Cochez M, Ferriol M, Oget N, Mieloszynski JL. Thermal degradation of methyl methacrylate polymers functionalized by phosphorus-containing molecules. Ill Cone calorimeter experiments and investigation of residues. Polym. Degrad. Stab. 2005 88 92-97. 

Phosphorus is known as an effective char promoter. Charring limits the release of fuels to the flame and therefore reduces the heat released. Moreover, the char accumulates on the surface of the material and can act as a protective layer which limits the heat transfer from the flame to the condensed phase and the gas transfer from the pyrolysis zone to the flame. This phenomenon is called the barrier effect. Nevertheless, it should be noted that the presence of char is not a sufficient condition to observe an effective barrier effect. Its structure (cohesion, porosity, thickness) is also veiy important but rarely studied. Thermal stability is another important parameter to assess the reaction to fire of a material. Indeed, the higher is the degradation temperature of a polymer, the greater is the heat required to start its pyrolysis. Table 12.2 lists the effects of phosphorus-containing groups on the thermal stability and charring for a variety of polymers. 

Hamciuc Corneliu, Vlad-Bubulac Tachita, Petreus Oana, and Lisa Gabriela. Kinetics of thermal degradation in non-isothermal conditions of some phosphorus-containing polyesters and polyesterimides. Eur. Polym. J. 43 no. 3 (2007) 980—988. 

Ho Tsung-Han, Leu Tsu-Shang, Sun Yih-Min, and Shieh Jeng-Yneh. Thermal degradation kinetics and flame retardancy of phosphorus-containing dicyclopentadiene epoxy resins. Polym. Degrad. Stab. 91 no. 10 (2006) 2347-2356. 

Petreus Oana, Lisa Gabriela, Avram Ecaterina, and Rosu Dan. Thermal degradation and pyrolysis study of phosphorus-containing polysulfones. J. Appl. Polym. Sci. 120 no. 6 (2011) 3233-3241. 

TibUetti Lucie, Ferry Laurent, Longuet Claire, Mas Andre, Robin Jean-Jacques, and Lopez-Cuesta Jose-Marie. Thermal degradation and fire behavior of thermoset resins modified with phosphorus containing styrene. Polym. Degrad. Stab. 97 no. 12 (2012) 2602-2610. 

Shao, C. H., Huang, J. J., Chen, G. N., Yeh, J. T., and Chen, K. N., Thermal and combustion behaviors of aqueous-based polyurethane system with phosphorus and nitrogen containing curing agent, Polym. Degrad. Stab., 1999, 65, 359-371. 

Another polyester type, i.e., polycarbonate, is rather seldom solvolytically depolymerized because of losing (at least partially) carbonate groups/bonds obtained via phosgene route synthesis. Troev et al. [29] recently described PC chemical degradation with dialkyl phosphonates (dimethyl or diethyl) or triethyl phosphate. The products, oligomeric carbonates containing phosphorus atoms, can be considered as precursors for the modification of various polymers by improving their flame-retardant properties, thermal stability, and adhesion. 

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