Vinyl alcohol from ethylene

As an alternative way, carbon has been loaded on Ti02 particles. This can be put in practice through the introduction of carbonaceous precursors on the Ti02 particles formed, and subsequent carbonization to produce Ti02-carbon composites. The carbon materials, derived from various carbonaceous precursors, have been practically introduced by means of thermal treatment in n-hexane, ethanol, or cyclohexane vapor [145-147,182-185] and carbonization of a mixture of Ti02 with poly(vinyl alcohol), poly(ethylene terephthalate), cellulose, sucrose, or citric acid [87,132-144,148,149,151]. A chemical vapor deposition method was also used to prepare MWCNTs deposited on Ti02 [198]. 

The Raman spectra of ethylene-vinyl alcohol copolymer and poly(vinyl alcohol) were measured and compared. The spectral changes that occurred during the dissolution of poly(vinyl alcohol) in, and the precipitation of films of poly(vinyl alcohol) from, both water and deuterium oxide were studied and the results were discussed. 46 refs. 

In intercalation of polymer from solution mode of nanocomposite synthesis, the organically modified silicate is dispersed in a solvent in which the polymer is also soluble. The polymer then adsorbs onto the delaminated sheets followed by the evaporation of the solvent. When the solvent is evaporated, the sheets reassemble, which also trap the polymer chains in between. Thus, an ordered multilayer structure is usually formed using this approach. The polymer chains loose entropy in the process of intercalation, which is compensated by the increase in the entropy of the solvent molecules due to their desorption from the filler interlayers. The technique is mostly used for the intercalation of the water-soluble polymers Uke poly(vinyl alcohol), poly(ethylene oxide), poly(acrylic acid), poly(vinlypyrroUdone), etc. [20-24], Later on, the use of this technique was also undertaken in organic solvents for polymers nonsoluble in water [25, 26],... 

After a number of efforts, the conunercial production of vinyl acetate from ethylene and AcOH was initially established as a Uquid phase process represented by the equation shown in Scheme 5. This process was later replaced by a gas phase process using a supported Pd catalyst. The commercial production of allyl acetate from propene and AcOH (Scheme 6) was also established by the gas phase. Allyl alcohol is produced by using this process. The outline of such developments was reviewed by Tsuji. ... 

Traditionally, pol5rmers (macromolecules) have been described in terms of component monomers (source) from which they are prepared, e.g., polystyrene, poly(vinyl acetate), poly(methyl methacrylate), or styrene-acrylonitrile copol3oner. Occasionally, even an assumed or hypothetical monomer is used, e.g., poly(vinyl alcohol) or ethylene-vinyl alcohol copolymer. Unlike well defined and well characterised low-molecular-weight compounds, polymers do not consist of identical molecules, but are mixtures of molecules of different molecular weights, and different sequences and shapes. 

Zhao X, Urano K, Ogasawara S. Adsorption of poly(ethylene vinyl alcohol) from aqneons solntion on montmorillonite clays. CoUoid Polym Sci 1989 267 899-906. 

PVA copolymers of vinyl alcohol and ethylene, poly[(vinyl alcohol)-co-ethylene] (EVOH), is industrially produced in significant quantities as an engineering plastic known as EVAL. A thermophilic EVOH-assimilating strain. Bacillus stearothermophilus, was isolated from the soil at 60 C by Tomita et al (1997). The apparent Fmax/ m value of the PVA copolymer with 10 mol% ethylene was over 10-fold greater than that of PVA (Hatanaka et al, 1995b). 

Oxidation of ethylene in alcohol with PdCl2 in the presence of a base gives an acetal and vinyl ether[106,107], The reaction of alkenes with alcohols mediated by PdCl2 affords acetals 64 as major products and vinyl ethers 65 as minor products. No deuterium incorporation was observed in the acetal formed from ethylene and MeOD, indicating that hydride shift takes place and the acetal is not formed by the addition of methanol to methyl vinyl etherjlOS], The reaction can be carried out catalytically using CuClj under oxygen[28]. 

Water-Soluble Films. Water-soluble films can be produced from such polymers as poly(vinyl alcohol) (PVOH), methylceUulose, poly(ethylene oxide), or starch (qv) (see Cellulose ethers Polyethers Vinyl polymers). Water-soluble films are used for packaging and dispensing portions of detergents, bleaches, and dyes. A principal market is disposable laundry bags for hospital use. Disposal packaging for herbicides and insecticides is an emerging use. 

Three generations of latices as characterized by the type of surfactant used in manufacture have been defined (53). The first generation includes latices made with conventional (/) anionic surfactants like fatty acid soaps, alkyl carboxylates, alkyl sulfates, and alkyl sulfonates (54) (2) nonionic surfactants like poly(ethylene oxide) or poly(vinyl alcohol) used to improve freeze—thaw and shear stabiUty and (J) cationic surfactants like amines, nitriles, and other nitrogen bases, rarely used because of incompatibiUty problems. Portiand cement latex modifiers are one example where cationic surfactants are used. Anionic surfactants yield smaller particles than nonionic surfactants (55). Often a combination of anionic surfactants or anionic and nonionic surfactants are used to provide improved stabiUty. The stabilizing abiUty of anionic fatty acid soaps diminishes at lower pH as the soaps revert to their acids. First-generation latices also suffer from the presence of soap on the polymer particles at the end of the polymerization. Steam and vacuum stripping methods are often used to remove the soap and unreacted monomer from the final product (56). 

Small amounts of TAIC together with DAP have been used to cure unsaturated polyesters in glass-reinforced thermo sets (131). It has been used with polyfunctional methacrylate esters in anaerobic adhesives (132). TAIC and vinyl acetate are copolymerized in aqueous suspension, and vinyl alcohol copolymer gels are made from the products (133). Electron cure of poly(ethylene terephthalate) moldings containing TAIC improves heat resistance and transparency (134). 

Suspension Polymerization. At very low levels of stabilizer, eg, 0.1 wt %, the polymer does not form a creamy dispersion that stays indefinitely suspended in the aqueous phase but forms small beads that setde and may be easily separated by filtration (qv) (69). This suspension or pearl polymerization process has been used to prepare polymers for adhesive and coating appHcations and for conversion to poly(vinyl alcohol). Products in bead form are available from several commercial suppHers of PVAc resins. Suspension polymerizations are carried out with monomer-soluble initiators predominantly, with low levels of stabilizers. Suspension copolymerization processes for the production of vinyl acetate—ethylene bead products have been described and the properties of the copolymers determined (70). Continuous tubular polymerization of vinyl acetate in suspension (71,72) yields stable dispersions of beads with narrow particle size distributions at high yields. 

Values for vinyUdene chloride copolymer and ethylene—vinyl alcohol are extrapolated from higher temperatures. 

Other developments in chelating resins include fibers made from poly(ethylene glycol) and poly(vinyl alcohol) to which EDA was attached with epichl orohydrin (281) and a styrene—divinylbenzene resin with pendant EDTA or DETPA groups (282). 

Transesterification has a number of important commercial uses. Methyl esters of fatty acids are produced from fats and oils. Transesterification is also the basis of recycling technology to break up poly(ethylene terephthalate) [25038-59-9] to monomer for reuse (29) (see Recycling, plastics). Because vinyl alcohol does not exist, poly(vinyl alcohol) [9002-89-5] is produced commercially by base-cataly2ed alcoholysis of poly(vinyl acetate) [9003-20-7] (see Vinyl polymers). An industrial example of acidolysis is the reaction of poly(vinyl acetate) with butyric acid to form poly(vinyl butyrate) [24991-31-9]. 

In addition to the above materials a number of copolymers containing vinyl acetate have been marketed. Ethylene-vinyl acetate (EVA) copolymers are discussed in Chapter 11 and vinyl chloride-vinyl acetate copolymers in Chapter 12. On the other hand, the commercial ethylene-vinyl alcohol copolymers, although derived from EVA, are considered briefly in this chapter since in weight terms the ethylene component is usually the minor one. 

The polymers are of interest as water-soluble packaging films for a wide variety of domestic and industrial materials. (Additional advantages of the poly(ethylene oxide)s are that they remain dry to the feel at high humidities and may be heat sealed.) The materials are also of use in a number of solution application such as textile sizes and thickening agents. As a water-soluble film they are competitive with poly(vinyl alcohol) whereas in their solution applications they meet competition from many longer established natural and synthetic water-soluble polymers. 

A dispersant that can be used in drilling fluids, spacer fluids, cement slurries, completion fluids, and mixtures of drilling fluids and cement slurries controls the rheologic properties of and enhances the filtrate control in these fluids. The dispersant consists of polymers derived from monomeric residues, including low-molecular-weight olefins that may be sulfonated or phosphonated, unsaturated dicarboxylic acids, ethylenically unsaturated anhydrides, unsaturated aliphatic monocarboxylic acids, vinyl alcohols and diols, and sulfonated or phosphonated styrene. The sulfonic acid, phosphonic acid, and carboxylic acid groups on the polymers may be present in neutralized form as alkali metal or ammonium salts [192,193]. 

HB Hopfenberg, A Apicella, DE Saleeby. Factors affecting water sorption in and solute release from glassy ethylene-vinyl alcohol copolymers. J Membrane Sci 8 273-281, 1981. 

Figure 5.6 Alcohols, aldehydes, ketones and acids 15, ethylene glycol 16, vinyl alcohol 17, acetaldehyde 18, formaldehyde 19, glyoxal 20, propionaldehyde 21, propionaldehyde 22, acetone 23, ketene 24, formic acid 25, acetic acid 26, methyl formate. (Reproduced from Guillemin et at. 2004 by permission of Elsevier)...

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