Phosphorus-containing aromatic

Flammability of Phosphorus-Containing Aromatic Polyesters A Comparison of Additives and Comonomer Flame Retardants... 

Composition and Self Quenching Times for Phosphorus Containing Aromatic Polyester Blends... 

Agrawal S, Narula AK. Synthesis and characterization of phosphorus containing aromatic poly(amide-imide)s copolymers for high temperature applications. Polym Bull 2013 70(12) 3241-60. 

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. 

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. 

Phenothiophosphine ring-containing polyamides and polyesters were also prepared by the polycondensation of 2,8-bischloroformyl-lO-phenylphenothiophos-phine 5,5, 10-trioxide with aromatic diamines such as 4,4 -diaminodiphenyl ether and 4,4 -diaminodiphenyl-methane, and bisphenols such as 4,4 -dihydroxybiphe-nyl and 4,4 -dihydroxydiphenylmethane, respectively [159]. These polymers are soluble in polar aprotic solvents and also exhibit good heat and fire resistance. Phosphorus containing high performance polymers are shown in Table 6. 

All the above structures contain the P—C—O—B fragment. Among boryloxyalkylphosphines and their derivatives with an exocyclic phosphorus containing group, (123)—(125) are reported (92IZV196). Such compounds were obtained from secondary phosphines, aromatic aide-... 

A powerful and efficient method for the preparation of poly(ketone)s is the direct polycondensation of dicarboxylic acids with aromatic compounds or of aromatic carboxylic acids using phosphorus pentoxide/methanesulfonic acid (PPMA)16 or polyphosphoric acid (PPA)17 as the condensing agent and solvent. By applying both of these reagents to the synthesis of hexafluoroisopropylidene-unit-containing aromatic poly(ketone)s, various types of poly(ketone)s such as poly(ether ketone) (11), poly(ketone) (12), poly(sulfide ketone) (13), and poly-... 

In spite of the general ambiphilicity of phosphonio-substituted phosphoHde derivatives, the aromaticity of the phosphoHde ring [10, 11] tends to reduce their electrophilicity while the intramolecular compensation of the negative charge by the phosphonio-substituents lowers at the same time their nucle-ophilicity [15, 16]. Bis-phosphonio-benzophospholides and -1,2,4-diaza-phospholides are therefore less reactive towards electrophiles and nucleophiles than other types of phosphorus containing multiple-bond systems and lack the notorious hydrolytic instabihty of many of these species [15, 16, 24]. Reactions are observed, however, with sufficiently strong electrophiles such as triflic acid or methyl triflate, or nucleophiles such as OH" or lithium alkyls, respectively. 

Substituted phosphorus heterocycles of varying degrees of unsaturation were easily obtained via Diels-Alder reaction and such adducts may be further aromatized or functionalized to provide phosphorus containing cage compounds < 1996PS(109)425, 1999S644, 1999EJ0363>. 

It can be presumed that under cold plasma conditions, the nitrogen and phosphorus containing polymers can lead also to the macroradicals through dehydrogenation of CH aromatic and aliphatic or NH groups. 

The large group of inhibitors of free radical chain reactions are frequently used in combination with metal salts or organometallic stabilizers. They are amines, sulfur- or phosphorus-containing compounds, phenols, alcohols, or chelates. Aromatic phosphites at about 1 p.p.r. chelate have undesirable metal impurities and inhibit oxidative free radical reactions. Some of the more popular are pentaerythritol, sorbitol, melamine, dicyan-diamide, and benzoguanamine. Their synergistic effect is utilized in vinyl floors where low cost is imperative. 

Polymers with an aromatic group in the main chain, however, such as polysulphones, polycarbonates and poly(phenylene oxides) proved to be intermediate in their smoke generation, possibly due to their considerable charring tendency. Also the unexpected drop in smoke density observed when poly(vinyl chloride) is partially chlorinated may be attributed to the high char yield. Einhom et al. (1968) concluded that smoke development decreases with increasing amount of chlorine- and phosphorus-containing additives, and with increasing cross-link density. 

Structural data available from experimental [22a] as well as theoretical [22c, 41] studies demonstrate that diphosphirenium salts 2 P also benefit from a certain amount of aromatic stabilization. However, the resonance energy of o4-phosphorus-containing systems is smaller. From a quantitative point of view, the electron delocalization in phosphirenium salts C has been calculated to be half that of the corresponding phosphirenylium salts H [42]. 

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