Phosphorus-containing polymers. thermal

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. 

Other phosphorus containing polymers that have been the subject of thermal stability studies include alkyl phosphate-type polyols [2] and poly(diethyl-2-(methacryl-oyloxy) ethyl phosphate [3]. 

Phosphorus-containing polymers have shown excellent thermal stability and good adhesion characteristics. In addition, phosphorus-containing polymers have been found to show excellent flame retardance [66,67]. All of the synthesized poly(arylene ether phosphine oxide)s (PAEPOs) (2-45 to 2-48) (Table 2.7) [68] exhibited excellent solubility at room temperature, including polar aprotic solvents, and also in chloroform, CH2CI2, and THF. These polymers also had good solubility... 

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. 

Phosphorus containing poly(maleimide-amines) were synthesized from N,N -bisdichloromaleimido-3,3 -diphenyl alkylphosphine oxides and aromatic diamines or piperazine [144]. The polymers prepared from piperazine are soluble in DMF, DM AC, DMSO, etc., but have poor thermal stability and flame retardancy. 

Polyphosphazenes are the most important and the most thermally characterized of the phosphorus-containing inorganic polymers. Linear, cycloli-near, and cross-linked cyclomatic polymers based on phosphazene structures have been produced. The repeating units of some polyphosphazenes are as follows ... 

The red allotropic form of phosphorus is relatively nontoxic and, unlike white phosphorus, is not spontaneously flammable. Red phosphorus is, however, easily ignited. It is a polymeric form of phosphorus, thermally stable up to ca. 450°C. In its finally divided form, it has proved to be a powerful flame-retardant additive.18 Elemental red phosphorus is a highly efficient flame retardant, especially for oxygen-containing polymers such as polycarbonates and polyethylene terephthalate). Red phosphorus is particularly useful in glass-filled polyamide 6,6, where high processing temperature (about 280°C) excludes the use of most phosphorus compounds.19 In addition, coated red phosphorus is used to flame retard nylon electrical parts, mainly in Europe and Asia.20... 

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. 

For polyester, the reported work82 done in Sichuan University of China, involves adding MMT clay in a copolymer of poly(ethyleneterephthalate), which with a phosphorus-containing monomer could produce PET with higher thermal stability and char-forming tendency. However, fibers were not produced from this PET-nanocomposite polymers. 

With regard to reactive flame-retardants, two routes can be followed to improve thermal stability and fire behavior of PU foams use of brominated or phosphorus-containing polyol or, for rigid foams, the introduction inside polymer backbone of more thermally stable structure than urethane, mainly isocyanurate, but also uretidione rings or carbodiimide.19... 

Oligomer 163 represents a stabilizer having PA chain with pendant phenolic moiety [31], Pendant hindered piperidine or piperazine moieties were attached to oligomeric stabilizers having polysulfonamide, polyurea (e.g. 164), or PA (e.g. 165) unis [213]. Polyhydrazide 166 was tested as HD AO and copper deactivator in PP [214]. Poly (nitrophenylene-carbazide disulfide) 167 was prepared for thermal stabilization of PVC. Phosphorus containing crosslinkable polymers having polyamide, polyimide and polyurea chains were prepared for flame and heat resistant applications [215]. 

Scheme 2.16 displays the thermal ROP of a number of phosphorous-bridged ferrocenophanes, resulting in the isolation of phosphorus(III)- and (V)-containing polymers 59a-c.115 Reaction of poly(ferrocenylphosphines) 59a-c with elemental sulfur generated poly(ferrocenylphosphine sulfides) 60a-c. Polymers 60a-c could not be directly prepared from thermal ROP of phosphine sulfide-bridged ferrocenophanes due to partial decomposition of the products. However, ferro-cenophane 58a polymerized via anionic ROP and reacted with sulfur.116 The resultant polymers had Mn = 3600-32,000 for monomer-catalyst ratios that were varied from 11 1 to 100 1. 

Relies and Schluenz (8) have reported the preparation of poly(maleimide-ethers) by using bisphenols and bisdichloromaleimides. These polymers were soluble in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) and gave tough flexible films. Phosphorus-containing poly(maleimide-amines) have been reported to have poor thermal stability and little flame retardation (9). 

Hamciuc C, Hamciuc E, Serbezeanu D, Vlad-Bubulac T. Thermal and optical properties of some phosphorus-containing poly(l,3, 4-oxadiazole-ester-imide)s. Polym Adv Tech-nol 2011 22(12) 2458-68. 

Phosphorus containing unsaturated polyesters Expandable graphite ammonium polyphosphate, triphenyl phosphate Flammability and thermal properties investigated, by UL 94 [13] and LOL Polymers containing ethylene glycol and ammonium polyphosphate showed the best flame retardance [44]... 

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. 

To overcome some problems with low molecular additives like leaching or low thermal stability, phosphorus-containing polymeric additives could be used. Phosphorus is incorporated into macromolecules used as an additive to improve the flame retardancy of a polymer. 

Wang Zheng, Wu Wei, Zhong Yuhua, Ruan Mingzhu, and Hui Lin Lin. Flame-retardant materials based on phosphorus-containing polyhedral oligomeric silsesquioxane and bismaleimide/DBA with improved thermal resistance and dielectric properties. J. Appl. Polym. Sci. 132 no. 9 (2015) 41545-41555. 

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