Polyvinyl alcohol

Polyvinyl alcohol [PVA] is a semi-crystalline water-soluble synthetic polymer made from hydrolysis of polyvinyl acetate. This material is also found to be biodegradable and mineralized in various environments. The degree of solubility and biodegradability as well as other physical attributes can be controlled by varying the MW and the degree of hydrolysis of the polymer [Chauhan, 2012]. 

Polyvinyl alcohol (PVA) is a vinyl polymer in which the main chains are joined only by carbon-carbon linkages. Among the vinyl polymers produced industrially, PVA is the only one known to be mineralised by microorganisms. PVA is water-soluble but also displays thermoplasticity [56]. 

In 1973, it was demonstrated for the first time that PVA was completely degraded and utilised by a bacterial strain. Pseudomonas 0-3, as a sole source of carbon and energy [9, 19]. 

Leja and G. Lewandowicz, Polish Journal of Environmental Studies, 2010, 19, 2, 255. 

Tokiwa, B.P. Calabia, C.U. Ugwu and S. Aiba, International Journal of Molecular Sciences, 2009,10, 9, 3722. 

Kulkarni, J. Reiche, J. Hartmann, K. Kratz and A. Lendlein, European Journal of Pharmaceutics and Biopharmaceutics, 2008,68, 1,46. 

7 Polyvinyl Alcohol (PVOH) and Ethylene Vinyl Alcohol (EVOH) 

PVOH has excellent barrier properties to oxygen and many other substances, because of its crystallinity and strong intermolecular forces. In its pure form, however, it is water soluble. Since the water solubility is imparted by the OH groups, the degree of solubility can be modified by controlling the amount of hydrolysis of 

The spectrum of polyvinyl alcohol (PVA), -(CH2CHOH)n, was the subject of much early study [Thompson and Tor-kington (228)] Elliott, Ambrose, and Temple (53) Blout and Karplus (77) Ambrose, Elliott, and Temple (6) Glatt, Webber, Seaman, and Ellis (66) Glatt and Ellis (65)], but with only 

The polarized infrared spectrum of an oriented specimen of PVA is shown in Fig. 11 [Krimm, Liang, and Sutherland (104)]. The band positions and polarization, given in Table 13, are derived from this and 

The assignment of the remaining bands presents somewhat greater problems. We will consider first the bands in the 1300—1500 cm-1 region of the spectrum. In earlier work [Krimm, Liang, and Sutherland (704)] the 

Several arguments suggest that the 1141 cm-1 band may be a v(CO) mode. Although this band is clearly associated with the crystalline regions, there is reason to believe that it is not correlated with the assumed structure. If it were, and its intensity increase on crystallization were a result of the presence of more crystalline chains, then we should expect other bands which are also due to the planar zig-zag chain conformation to similarly increase in intensity. There is no evidence that this is the case. It would therefore seem that this band is associated with a structure that is more likely when the chain is in the crystalline state, a structure which represents only a small modification of that proposed by Bunn. We wish to suggest that this band may be associated with the v (CO) mode 

Of the remaining modes to be assigned, yt (Cli2) is not identifiable with any certainty. The 5 (CO) and yw (CO) modes are probably to be associated with the bands at 480 cm-1 and 410 cm-1 respectively. It seems not unlikely that the 185 cm-1 band, and perhaps also the shoulder at 135 cm-1, arises from a y(OH O) vibration [Gross (69)], i.e., a vibration in which the O O distance changes but not the OH distance. Many of the high frequency bands seem to be interpretable in terms of binary combinations, and some of these are suggested. 

Airvol Alcotex Elvanol Gelvatol Gohsenol Lemol Mowiol, Polyvinol PVA vinyl alcohol polymer. 

Polyvinyl alcohol is a water-soluble synthetic polymer represented by the formula (C2H40) . The value of n for commercially available materials lies between 500 and 5000, equivalent to a molecular weight range of approximately 20 000-200 000, see Table I. 

Polyvinyl alcohol occurs as an granular powder. odorless, white to cream-colored  

Coating agent lubricant stabilizing agent viscosity-increasing agent. 

Polyvinyl alcohol is used primarily in topical pharmaceutical and ophthalmic formulations see Table It is used as a 

The combination of starch with a water-soluble polymer such as PVA (or polyalkylene glycols) has been widely considered since 1970 [101]. 

Since the early 1990s these compositions have been mainly studied for starch-based loose-fill production as a substitute for expanded PS [102-108], using compositional water as the expanding gas. In these kinds of blends, not only natural starch but also modified ones such as hydroxy propylated high amylose starch can be used, especially to improve foam resilience and density [102-108]. Optimisation of the composition and foaming processes have been pursued over the years in order to 

Starch can also be destructurised in the presence of more hydrophobic polymers totally incom- patible with starch, such as aliphatic polyesters (APE) [112]. 

Due to their low melting points APE are difficult to process using conventional thermoplastic material techniques (i.e., film blowing and blow moulding). It has been found that the blending of starch with APE improves their processability and biodegradability. 

The presence of compatibilisers between starch and APE is preferred. Some examples are amylose/EVOH V-type complexes [92] and starch-grafted polyesters. The use of chain extenders such as diisocyanates and epoxides is preferred such materials are characterised by excellent compostability, excellent mechanical properties and reduced sensitivity to water. 

Left ultimate tensile strength Right yield strain 

Dose dependence of molecular weight in polyoxymethylene copolymer during irradiation in a vaouum [737] 

As the radiation dose increases, melt temperature and density decrease. Discoloration also occurs. During irradiation, carbon dioxide, methane, hydrogen, methanol, and dimethyl ether are eliminated [32]. Because these low-molecular compounds are diffusing, a weight loss of 0.5% is expected with a dose of 200 kGy [737]. 

Stress-strain diagram of polyoxymethylene copolymer, irradiation in vacuum at 15 °C with 1 MeV electrons from a van de Graafgenerator [737] 

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Liquid or solid films which reduce or prevent adhesion between surfaces solid-solid, solid-paste, solid-liquid. Waxes, metallic soaps, glycerides (particularly stearates), polyvinyl alcohol, polyethene, silicones, and fluorocarbons are all used as abherents in metal, rubber, food, polymer, paper and glass processing. 

Ethyne is the starting point for the manufacture of a wide range of chemicals, amongst which the most important are acrylonitrile, vinyl chloride, vinyl acetate, ethanal, ethanoic acid, tri- and perchloro-ethylene, neoprene and polyvinyl alcohol. Processes such as vinylation, ethinylation, carbonylation, oligomerization and Reppe processes offer the possibility of producing various organic chemicals cheaply. Used in oxy-acetylene welding. 

C. A. Finch, ed.. Polyvinyl Alcohol Properties and Application, John Wiley Sons, Ltd., Chichester, U.K., 1973, Chapt. 9. 

Cross-Linking of Polyols. Polyols such as natural polysaccharides, eg, cellulose, starch, guar gum and their derivatives, and polyvinyl alcohol and its derivatives can be cross-linked by organic titanates. 

R. K. Tubbs, H. K. Inskip, and P. M. Subiamanian, Properties and Applications of Polyvinyl Alcohol, Society of Chemical Industiy, London, 1968, p. 88. 

S. Noma, Polyvinyl Alcohol, First Osaka Symposium, Kobunshi Gakkai, Tokyo, Japan, 1955, pp. 81—103. 

Free flow. Dobry and Finn [Chem. Eng. Prog., 54, 59 (1958)] used upward flow, stabilized by adding methyl cellulose, polyvinyl alcohol, or dextran to the background solution. Upward flow was also used in the electrode compartments, with cooling efficiency sufficient to keep the main solution within 1°C of entering temperature. 

Polymeric Membranes Economically important applications required membranes that could operate at higher pH than could CA, for which the optimum is around pH = 5. Many polymeric membranes are now available, most of which have excellent hydrolytic stabihty. Particularly prominent are polysulfone, polyvinyhdene fluoride, poly-ethersulfone, polyvinyl alcohol-polyethylene copolymers, and aciylic copolymers. 

Bead Polymerization Bulk reaction proceeds in independent droplets of 10 to 1,000 [Lm diameter suspended in water or other medium and insulated from each other by some colloid. A typical suspending agent is polyvinyl alcohol dissolved in water. The polymerization can be done to high conversion. Temperature control is easy because of the moderating thermal effect of the water and its low viscosity. The suspensions sometimes are unstable and agitation may be critical. Only batch reaciors appear to be in industrial use polyvinyl acetate in methanol, copolymers of acrylates and methacrylates, polyacrylonitrile in aqueous ZnCh solution, and others. Bead polymerization of styrene takes 8 to 12 h. 

FINCH, c.A. (Ed.), Polyvinyl alcohol Properties and Applications, Wiley New York (1973) PRITCHARD, J.G., Poly(Vinyl alcohol) Basic Properties and Uses, Macdonald, London (1970) Properties and Applications of Polyvinyl Alcohol (SCI Monograph No. 30), Society of the Chemical Industry, London (1968)... 

Neoprene latex 115 contains a copolymer of chloroprene and methacrylic acid, stabilized with polyvinyl alcohol [15], With respect to other polychloroprene latices, this latex has two major advantages (1) excellent colloidal stability, which gives high resistance to shear and a broad tolerance to several materials ... 

Other components in PVAc-formulations are defoamers, stabilizers, filler dispersants, preservatives, thickeners (hydroxyethylcellulose, carboxymethylcellu-lose), polyvinyl alcohols, starch, wetting agents, tackifiers, solvents (alcoholes, ketone, esters), flame retardants and others. 

Beaded polymeric support, whether polystyrene-divinylbenzene, polymethacrylate, or polyvinyl alcohol, is conventionally produced by different variations of a two-phase suspension polymerization process, in which liquid microdroplets are converted to the corresponding solid microbeads (1). 

Synthetic organic polymers, which are used as polymeric supports for chromatography, as catalysts, as solid-phase supports for peptide and oligonucleotide synthesis, and for diagnosis, are based mainly on polystyrene, polystyrene-divinylbenzene, polyacrylamide, polymethacrylates, and polyvinyl alcohols. A conventional suspension of polymerization is usually used to produce these organic polymeric supports, especially in large-scale industrial production. 

Heitz et al. (33) also described the preparation of polyvinyl acetate cross-linked with butanediol divinyl ether. The polymer is the base of the Merckogel series of size exclusion chromatography packings, and its hydrolyzed derivative, polyvinyl alcohol, is marketed as Fractogel and Toyopearls. 

A process for the preparation of porous polyvinyl alcohol gels in three steps is (1) suspension polymerization of vinyl acetate with diethylene glycol dimethacrylate in the presence of a diluent as porogen, (2) saponifying of the resulting porous polyvinyl acetate gel with an alkali, and then (3) subjecting... 

A weak cation-exchange resin is obtained by reaction of glyoxylic acid and a cross-linked polyvinyl alcohol. The polyvinyl alcohol is cross-linked with glutaraldehyde in the presence of hydrochloric acid. The cation-exchange resin has an exchange capacity of 3 meq/g or greater and a swelling volume of 10 ml/g or smaller (37-38). 

A polyvinyl alcohol is obtained by suspension polymerization of vinyl acetate and the cross-linking agent, triallyl isocyanurate, with a triazine ring followed by alkali hydrolysis. The polyvinyl alcohol gel is used as packing for gel-... 

Macroporous polyvinyl alcohol particles with a molecular weight cutoff of ca. 8 X 10 in gel-permeation chromatography have been prepared. The particles are produced by first dispersing an aqueous solution of polyvinyl alcohol in an organic solvent to make spheres of polyvinyl alcohol solution. Holding the dispersion in such a state that a gel will then form spontaneously will cause the gel to react with glutaraldehyde in the presence of an acidic catalyst (85). 

Nonionic hydrophilic Polyethylene glycol Soluble starch, methyl cellulose, pullulan Dextran Above samples plus hydroxyethyl cellulose, polyvinyl alcohol, polyacrylamide Distilled water 0.01 N NaOH DMSO Buffer or salt solution (e.g., 0.1— 0.5 M NaNO,)... 

Individual components in the formulation of the aqueous phase all contribute to the successful production of a GPC/SEC gel. The stabilizer acts as a protective coating to prevent the agglomeration of the monomer droplets. Polyvinyl alcohol, gelatin, polyacrylic acids, methylcellulose, and hydroxypro-... 

Styrene—divinylbenzene copolymer Polyhydroxymethaerylate Polyvinyl alcohol Polyhydroxylated silica... 

The packed columns of Shodex Asahipak GF/GS HQ series are made of an especially modified polyvinyl alcohol based resin (Table 6.11, page 202). 

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