Aromatic polyphenylene oxide

We were, however, at a later date able to synthesize the completely aromatic polyphenylene oxide from 2,-6-diphenylphenol which we called P3O. 

Polypropylene has a chemical resistance about the same as that of polyethylene, but it can be used at 120°C (250°F). Polycarbonate is a relatively high-temperature plastic. It can be used up to 150°C (300°F). Resistance to mineral acids is good. Strong alkalies slowly decompose it, but mild alkalies do not. It is partially soluble in aromatic solvents and soluble in chlorinated hydrocarbons. Polyphenylene oxide has good resistance to ahphatic solvents, acids, and bases but poor resistance to esters, ketones, and aromatic or chlorinated solvents. 

A stable material in humid conditions at temperatures up to 105°C, polyphenylene oxide is resistant to most aqueous solutions of acids and alkalis but is attacked by many organic solvents, particularly by aromatics and chlorinated aliphatics. 

Engineering polymers are often used as a replacement for wood and metals. Examples include polyamides (PA), often called nylons, polyesters (saturated and unsaturated), aromatic polycarbonates (PCs), polyoxymethylenes (POMs), polyacrylates, polyphenylene oxide (PPO), styrene copolymers, e.g., styrene/ acrylonitrile (SAN) and acrylonitrile/butadiene/styrene (ABS). Many of these polymers are produced as copolymers or used as blends and are each manufactured worldwide on the 1 million tonne scale. 

Polyphenylene oxide and polyphenylene ether are oxides or ethers like polyoxymethylene but an aromatic unit replaces the methylene group leading to — ( — C6H4 — O—) — Polyphenylene ether has too high a glass transition temperature to be easily processed and is marketed in the form of alloys with other resins, such as ... 

Aromatic cyclic chains are more stable than aliphatic catenated carbon chains at elevated temperatures. Thus linear phenolic and melamine polymers are more stable at elevated temperatures than polyethylene, and the corresponding cross-linked polymers are even more stable. In spite of the presence of an oxygen or a sulfur atom in the backbones of polyphenylene oxide (PPO), polyphenylene sulfide (PPS), and polyphenylene sulfone, these polymers are... 

Other macromolecules are formed by condensing their monomers to form a repeat functional group (e.g., esters, amides, ethers) interspersed by alkyl chains, aromatic rings, or combinations of both. These condensations are characterized frequently, although not always by the loss of some by product (e.g., water, alcohol). The methods of formation of these polymers are far more varied than those of addition polymers. Examples of condensation polymers are (a) poly(esters), (b) poly(urethanes), (c) poly (carbonate), and (d) polyphenylene oxide). 

Phenols are oxidized by NaBiO3 to polyphenylene oxides, quinones, or cyclohexa-2,4-dienone derivatives, depending on the substituents and the reaction conditions [263]. For example, 2,6-xylenol is oxidized in AcOH to afford a mixture of cyclohexa-dienone and diphenoquinone derivatives (Scheme 14.123) [264] and is oxidatively polymerized in benzene under reflux to give poly(2,6-dimethyl-l,4-phenylene) ether (Scheme 14.124) [265]. Substituted anilines and a poly(phenylene oxide) are oxidatively depolymerized by NaBiO, to afford the corresponding anils [266]. Nal iO, oxidizes olefins to vicinal hydroxy acetates or diacetates in low to moderate yield [267]. Polycyclic aromatic hydrocarbons bearing a benzylic methylene group are converted to aromatic ketones in AcOH under reflux (Scheme 14.125) [268]. 

Spin relaxation in dilute solution has been employed to characterize local chain motion in several polymers with aromatic backbone units. The two general types examined so far are polyphenylene oxides (1-2) and aromatic polycarbonates (3-5) and these two types are the most common high impact resistant engineering plastics. The polymer considered in this report is an aromatic polyformal (see Figure 1) where the aromatic unit is identical to that of one of the polycarbonates. This polymer has a similar dynamic mechanical spectrum to the impact resistant polycarbonates (6 ) and is therefore an interesting system for comparison of chain dynamics. 

Sulfonation of aromatic polymers has been explored as a method to produce hydrophilic polymers with water permeability and salt rejection characteristics. These have been of interest because of their potentially high degree of chlorine resistance. The use of sulfonated aromatic polymers for reverse osmosis membranes began in the late 1960 s with the work of Plummer, Kimura and LaConti of General Electric Company.82 Polyphenylene oxide [poly(2,6-di-... 

In the case of friction of thermostable polyphenylen oxides (PPO) containing substituted aromatic nuclei in macromolecules, mainly cresol and small amounts of xylenol are derived. As a result, a secondary heat resistant structure is formed on the friction surface of PPO parts. The material with a hybrid structure of caged snake type based on PPO in combination with polymaleimide displays better wear resistance owing to its cross-linked structure. The tribochemical lubrication in such pairs is produced via tribological decomposition of less heat-resistant polymers [98]. 

Research in this area has resulted in the preparation of several comb polymers (Halasa, 1974 Folket al., 1044). The metallation technique is a useful and versatile method as it can be used with any polymeric material that contains a few double bonds. For example, ethylene-propylene was successfully grafted with norbornene. Similar reactions were performed on polymeric materials that contain aromatic rings, such as polystyrene, poly-a-methyl styrene, and polyphenylene oxide (PPO). 

Polyphenylene oxide has excellent resistance to aqueous envirorunents, dilute mineral acids, and dilute alkalies. It is not resistant to aliphatic hydrocarbons, aromatic hydrocarbons, ketones, esters, or chlorinated hydrocarbons. Refer to Table 2.30 for the compatibility of PPO with selected corrodents. Reference [1] provides a more extensive listing. 

Polyether ether ketone (PEEK) has poor resistance to UV. Reinforced grades are available and, where some degree of UV resistance is required, carbon black may be added. Polyphenylene oxide (PPO) and polysulfone are susceptible to photodegradation due to their aromatic content, although PPO in its usual form as a stabilized polymer alloy is somewhat better. It is inadvisable to use any of these polymers for prolonged exposure without protection. 

Hoehn HH (1985) Aromatic polyamide membranes. In Lloyd DR (ed) Materials science of synthetic membranes. ACS Symposium Series 269. American Chemical Society, Washington, DC, p 81 Matsuura T (2001) Reverse osmosis and nanofiltration by composite polyphenylene oxide membranes. In Chowdhury G, Kruczek B, Matsuura T (eds) Polyphenylene oxide and modified polyphenylene oxide membranes. Kluwer, Dordrecht, p 181... 

The term polyphenylene oxide (PPO) is a misnomer for a polymer that is more accurately named poly-(2,6-dimethyl-p-phenylene ether), and which in Europe is more commonly known as a polymer covered by the more generic term polyphenyleneether (PPE). This engineering polymer has high-temperature properties due to the large degree of aromaticity on the backbone, with dimethyl-substituted benzene rings joined by an ether linkage, as shown in Fig. 2.32. 

The next two decades saw the development of new polymers such as thermoplastic PU (1961), aromatic polyamides, polyimides (1962) polyaminimides (1965), thermoplastic elastomers (styrene-butadiene block copolymers in 1965), ethylene-vinyl acetate copolymer, ionomers (1964), polysulfone (1965), phenoxy resins, polyphenylene oxide, thermoplastic elastomers based on copolyesters, poly butyl terephthalate (1971) and polyarylates (1974). 

Oligomeric aromatic phosphates have been patented and commercially used as flame-retardant additives mainly for impact-resistant polystyrene blends with polyphenylene oxide and polycarbonate blends with acrylonitrile-butadiene-styrene (ABS) copolymers (130,131). They have also been shown useful in thermoplastic polyesters (92). The principal commercial examples are based on phenol and resorcinol (Akzo-Nobel s Fyrolflex RDP) or phenol and bisphenol A (Akzo-Nobel s Fyrolflex BDP or Albemarle s Ncendx P-30). Although these have the diphosphate as their principal ingredient, they also contain higher oligomers. 

Isayev A I and Subramanian P R (1991) Self-reinforced composite of thermotropic liquid crystalline polymers and process for preparing same, U.S. Patent 5,070,157, Austr Patent 645,154 (1994), Eur Patent EP 0543 953 (1997), Can Patent 2,086,931 (1993), Jap Patent 2 841 246, French Patent 0543953, Ger Patent 69125493.1, Great Brit Patent 0543953, Int Patent WO 92/03506 (1992). Isayev A I (1991) Wholly aromatic polyester fiber-reinforced polyphenylene oxide and process for preparing same, U.S. Patent 5,006,403. 

Polyphenylene oxide, or polyphenylene ether, is an amorphous polymer for which the IR and Raman spectra are presented in Reference Spectrum 45. As expected from the chemical structure, bands relevant to the aromatic ring system are observed at 1601, 1492, and 858 cm (IR), and 1603 and 835 cm (Raman)—the low-frequency band in the IR being associated with the substitution of the aromatic ring. The other important feature of the IR spectrum of polyphenylene oxide is the intense absorption band at 1188 cm associated with the ether bonding. 

Polyphenylene oxide may be alloyed with polystyrene at any ratio. Significant overlap of the aromatic spectral features will be experienced, as noted in Fig. 43. The 760 and 699 cm bands of polystyrene are readily observed, even at low concentrations. Estimation of the polyphenylene oxide content of the alloys with polystyrene may be obtained from the intensity ratio of the 1021 cm (PPO) and 699 cm (PS) bands as follows [73] ... 

Others. Other polymers are being investigated as potential precursors for glassy carbon, such ets polyvinyiidene chloride (CH2CCl2) , polyvinyl alcohol (CH2CHOH), polyphenylene oxide and aromatic epoxy. The latter two compounds have a high carbon yield. 

The utilization of pendant groups to promote solubility in common organic solvents was first demonstrated with the aromatic polyphenylenes. Polymers prepared by the oxidation of benzene or dehydrogenation of polycyclohexadiene are crystalline materials and insoluble. Phenylated polyphenylenes obtained from the Diels-Alder polymerization of bistetracyclones with m- or p- diethynylbenzene are amorphous materials and are soluble in toluene. The pendant phenyl groups serve to decrease crystallinity and promote solubility. 

The syntheses of three new aromatic ionomers with equivalent weights of ca. 800, 600 and 400 have been carried out. Thus, 3,3(oxydi P phenylene)bis[2,4,5-triphenylcyclo-pentadienone] and 3,3 -(oxydi-p-phenylene)bis[2,5-diethoxy-carbonyl-4-phenylcyclopentadienone] were copolymerized with 4,4 -diethynyldiphenyl ether in molar ratios of 70 30 100, 60 40 100 and 40 60 100 to afford the corresponding alkoxy-carbonyl-substituted polyphenylene oxides, which were converted to the ionomers by treatment with potassium hydroxide. 

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