Polyethylene ether carbonate

When reacting either ethylene carbonate or propylene carbonate with an aliphatic diamine, a polyurethane can be produced (Figure 2.14). Polyethylene ether carbonate) diols (Harris et al., 1990), when fabricated into polyurethanes using MDI and BDO, produce elastomers that have polyester polyol features. This was shown using 13C NMR. The structure gives rise to potential for a very high virtual cross-linking density. These carbonate-derived polyesters have superior hydrolysis resistance compared to the traditional materials. 

PCIA Personnel Communications Industry PEEC polyethylene ether carbonate... 

Infrared spectroscopy has also been used to determine hydroxyl groups in polyethers [20], polyethylene ether carbonate [21], and carboxy terminated polybutadiene [22, 23] and hydroxybutadienes [24]. 

Multiwalled carbon nanotube-polypropylene Multiwalled carbon nanotube-high-density polyethylene Multiwalled carbon nanotube-polyimides Single-walled carbon nanotube-vinylene Carbon nanotube-polyether ether ketone Multiwalled carbon nanotube-polycarbonate TjOj-coated multiwalled carbon nanotube-epoxy composites Carbon nanotube polyetherimide and epoxy resins Carbon nanotube polypyrrole... 

Polymers, metals, ceramics, and glasses may be utilized as biomaterials. Polymers (see Ppolymerprocessing), an important class of biomaterials, vary gready in stmcture and properties. The fundamental stmcture may be one of a carbon chain, eg, in polyethylene or Tedon, or one having ester, ether, sulfide, or amide bond linkages. PolysiHcones, having a —Si—O—Si— backbone, may contain no carbon. 

The solvent can be tailored to provide selective acid gas removal based on the Hquid—gas solubiHties. For example, the Selexol process, Hcensed by Union Carbide Corporation, uses the dimethyl ether of polyethylene glycol (DMPEG) to provide high hydrogen sulfide selectivity. The solubiHty of hydrogen sulfide in DMPEG is 8—10 times that of carbon dioxide. 

Polymers used for seat and plug seals and internal static seals include PTFE (polytetrafluoroeth ene) and other fluorocarbons, polyethylene, nylon, polyether-ether-ketone, and acetal. Fluorocarbons are often carbon or glass-filled to improve mechanical properties and heat resistance. Temperature and chemical compatibility with the process fluid are the key selec tion criteria. Polymer-lined bearings and guides are used to decrease fric tion, which lessens dead band and reduces actuator force requirements. See Sec. 28, Materials of Construction, for properties. 

Preparation of 9a-Fluoro-110,17a,21-Trihydroxy-160-Methyl-4-Pregnene-3,2O-Dione 21-Acetate To a solution of 200 mg of 9(3,11(3-epoxy-1 7a,21-dihydroxy-16(3-methyl-4-pregnene 3,20-dione 21-acetate in 2 ml of chloroform and 2 ml of tetrahydrofuran in a polyethylene bottle at -60°C was added 2 ml of a 2 1 (by weight) mixture of anhydrous hydrogen fluoride and tetrahydrofuran. After 4 hours at -10°C the mixture was cooled to -60°C and cautiously added to a stirred mixture of 30 ml or 25% aqueous potassium carbonate and 25 ml of chloroform kept at -5°C. The aqueous phase was further extracted with chloroform and the latter phase washed with water and dried over magnesium sulfate. The residue on crystallization from acetone-ether gave pure 9a-fluoro-11(3,17a,21-trihydroxy-16(3-methyl-4-pregnene-3,20-dione 21-acetate. 

Important processes commercially used are the Selexol, the Sulfinol, and the Rectisol processes. In these processes, no chemical reaction occurs between the acid gas and the solvent. The solvent, or absorbent, is a liquid that selectively absorbs the acid gases and leaves out the hydrocarbons. In the Selexol process for example, the solvent is dimethyl ether of polyethylene glycol. Raw natural gas passes countercurrently to the descending solvent. When the solvent becomes saturated with the acid gases, the pressure is reduced, and hydrogen sulfide and carbon dioxide are desorbed. The solvent is then recycled to the absorption tower. Figure 1-1 shows the Selexol process. ... 

BritP 586224(1947) CA 41, 7120(1947) (Inclusion of 0.4% of polyethylene glycol ether contg at least 8 carbon atoms)... 

Because of the presence of ether groups and terminal hydroxyl groups, polyethylene oxide (PEO) is also soluble in water. Likewise, polyvinyl alcohol (PVA), which contains a hydroxyl group on most of the alternate carbon atoms in the linear chain, is soluble in water. 

A solution of 690 g. (5.0 moles) of potassium carbonate in 2 1. of distilled water is prepared in a 4-1. polyethylene beaker or pail, and 500 g. of crushed ice and 300 ml. of ether are added. The cold reaction mixture is cautiously added to the carbonate solution with stirring. The pH of the aqueous layer becomes about 9. The ether layer is separated, and the aqueous layer is extracted with three 200-ml. portions of ether. The ether solutions are combined and washed with three 100-ml. portions of water. The ether solution is dried over anhydrous sodium sulfate, and the ether is removed by distillation. The oily residue is fractionated through a 15-cm. Vigreux column under reduced pressure. There is a fore-run of about 0.5 ml., and then 59-75 g. (60-77%) of l-bromo-2-fluoroheptane is collected at 70-78° (15 mm.) 25d 1.4408-1.4420. According to vapor phase chromatography, it is about 90% pure (Note 5). 

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