Polyphenylene ethers

The above examples show that it is stiU unclear what is the minimum concentration 

Because of their hydrolytic stability, both at room and elevated temperatures, blended parts in PPE can be repeatedly steam sterilized with no significant change in their properties. When exposed to aqueous environments their dimensional changes are low and predictable. PPE s resistance to acid, bases, and detergents is excellent. However, it is attacked by many halogenated or aromatic hydrocarbons. 

Vestoran 1900 Specimen Bent strip test, 3.5% outer fiber strain 

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Polymerization Solvent. Sulfolane can be used alone or in combination with a cosolvent as a polymerization solvent for polyureas, polysulfones, polysUoxanes, polyether polyols, polybenzimidazoles, polyphenylene ethers, poly(l,4-benzamide) (poly(imino-l,4-phenylenecarbonyl)), sUylated poly(amides), poly(arylene ether ketones), polythioamides, and poly(vinylnaphthalene/fumaronitrile) initiated by laser (134—144). Advantages of using sulfolane as a polymerization solvent include increased polymerization rate, ease of polymer purification, better solubilizing characteristics, and improved thermal stabUity. The increased polymerization rate has been attributed not only to an increase in the reaction temperature because of the higher boiling point of sulfolane, but also to a decrease in the activation energy of polymerization as a result of the contribution from the sulfonic group of the solvent. 

When chloroform or methanol is used as the solvent for the oxidation of phenols, other products, originating from coupling of aryloxy radicals, e.g., polyphenylene ethers and/or diphenoquinones, are also formed. ... 

The successful development of polyfethylene terephthalate) fibres such as Dacron and Terylene stimulated extensive research into other polymers containing p-phenylene groups in the main chain. This led to not only the now well-established polycarbonates (see Chapter 20) but also to a wide range of other materials. These include the aromatic polyamides (already considered in Chapter 18), the polyphenylene ethers, the polyphenylene sulphides, the polysulphones and a range of linear aromatic polyesters. 

The main experimental techniques used to study the failure processes at the scale of a chain have involved the use of deuterated polymers, particularly copolymers, at the interface and the measurement of the amounts of the deuterated copolymers at each of the fracture surfaces. The presence and quantity of the deuterated copolymer has typically been measured using forward recoil ion scattering (FRES) or secondary ion mass spectroscopy (SIMS). The technique was originally used in a study of the effects of placing polystyrene-polymethyl methacrylate (PS-PMMA) block copolymers of total molecular weight of 200,000 Da at an interface between polyphenylene ether (PPE or PPO) and PMMA copolymers [1]. The PS block is miscible in the PPE. The use of copolymers where just the PS block was deuterated and copolymers where just the PMMA block was deuterated showed that, when the interface was fractured, the copolymer molecules all broke close to their junction points The basic idea of this technique is shown in Fig, I. 

The C(ls) and 0(ls) spectra of polyphenylene ether (PPE) before and after evaporation of chromium onto the surface are shown in Fig. 23. C(ls) spectra of neat PPE consisted of two components, near 284.6 and 286.0 eV, that were assigned to carbon atoms in the benzene and methyl groups and in the ether groups, respectively. The 0(ls) spectrum consisted of a single peak, near 533.4 eV, that was assigned to the ether oxygen atoms. After evaporation of chromium, a new peak related to formation of Cr202 was observed near 531.0 eV. 

Fig. 23. C(ls) and 0(ls) spectra of polyphenylene ether before (hottom) and after (top) deposition of 0.4 nm of chromium. Reproduced hy permission of Gordon and Breach Science Publishers from Ref. [28].

Poly(ethylene terephtlhalate) Phenol-formaldehyde Polyimide Polyisobutylene Poly(methyl methacrylate), acrylic Poly-4-methylpentene-1 Polyoxymethylene polyformaldehyde, acetal Polypropylene Polyphenylene ether Polyphenylene oxide Poly(phenylene sulphide) Poly(phenylene sulphone) Polystyrene Polysulfone Polytetrafluoroethylene Polyurethane Poly(vinyl acetate) Poly(vinyl alcohol) Poly(vinyl butyral) Poly(vinyl chloride) Poly(vinylidene chloride) Poly(vinylidene fluoride) Poly(vinyl formal) Polyvinylcarbazole Styrene Acrylonitrile Styrene butadiene rubber Styrene-butadiene-styrene Urea-formaldehyde Unsaturated polyester... 

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 ... 

Summary of some general assessments concerning chemical behaviour at room temperature of polyphenylene-ether and polypropylene, which are not necessarily representative of PPE/PP alloys or of all grades of PPE and PP. These general indications should be verified by consultation with the producer of the selected alloys and by tests under operating conditions. 

Chromic or sulfo-chromic acid etching, for polyolefins, polystyrene, ABS, polyacetal, polyphenylene ether. .. These treatments have two effects ... 

PolyOxyMethylene or Polyacetal Polypropylene PolyPhthalAmide PolyPhenylene Ether... 

Hodgdon, R. B. and Hay, A. S. 1970. Sulfonated aryl-substituted polyphenylene ether ion exchange membranes. US Patent 3,528,858. 

PS (polystyrene), PVC [poly(vinyl chloride)], PC (bisphenol A polycarbonate) PMMA [poly (methyl methacrylate)], PB (polybutadiene), SAN (styrene-acrylonitrile copolymer),NBR (acrylonitrile-butadiene rubber), PPE (polyphenylene ether), SBR (styrene-butadiene rubber)... 

Electroconductive resin compositions, which are useful for packaging electronic devices, have been described. In general, electroconductive resin compositions are made up from a thermoplastic resin and an electroconductive filler, mostly carbon black. Polyphenylene ether) resins are known to impart heat resistance. For general purposes, a poly(styrene) (PS) resin and an ABS resin are superior to other resins in that even if carbon black is incorporated in a large amount, there will be no substantial decrease in the flowability or... 

Diphenoqinones were concomitant products. This was the first synthesis of a linear polyphenylene ether with high enough molecular weight to have useful physical properties. 

Waters (39) has described the oxidation of 2.6-dimethylphenol with alkaline ferricyanide. The products he obtained were the diphenoquinone (VIII R=R,=CH3) and an amorphous material (M.W. 800) which he did not further characterize. In retrospect, it would appear that this product was a low molecular weight polyphenylene ether (VII R=R1=CH3). 

The decomposition of benzene-1.4-diazooxide might be expected to give as an intermediate (XI) which could possibly polymerize to a polyphenylene ether. In 1956, Sus studied the photochemical decomposition of benzene-1.4-diazooxide (79). He states... 

Price (74) has reported an attempted preparation of a polyphenylene ether via a pyrolysis of mercuriacetates. Only insoluble products were obtained. 

III. Structure and properties of aromatic polyethers 1. Halogen substituted polyphenylene ethers... 

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