Polyvinyl acetate monomer

Group of plastics composed of resins derived from vinyl monomers, excluding those that are covered by other classifications (i.e., acrylics and styrene plastics). Examples include PVC, polyvinyl acetate, polyvinyl butyral, and various... 

Vinyl acetate is a reactive colorless liquid that polymerizes easily if not stahilized. It is an important monomer for the production of polyvinyl acetate, polyvinyl alcohol, and vinyl acetate copolymers. The U.S. production of vinyl acetate, the 40th highest-volume chemical, was approximately 3 hillion pounds in 1994. 

Abbreviations HCL Hydrochloric Acid ABS Acrylonitrile Butadiene Styrene PVC Polyvinyl Chloride VAM Vinyl Acetate Monomer... 

Standard Oil Co. claims the use of polyisobutylene as a plasticizer for polyvinyl acetate. Copolymers of isobutylene with vinyl ethers and other monomers are mentioned in several patents. For synthetic rubbers, oligomers of butadiene are claimed. Rubberlike polyolefins (10 to 50% is sufficient) are used extensively for plasticizing phenolic resins to increase impact strength. 

Polyvinyl acetate polymers synthesized by emulsion polymerization168, show strikingly different behavior188,189). Figure 41 shows Dz as a function of Mw. For the low molecular weights, D2 decreases as expected but from Mw = 14 106 onwards Dz remains constant. The measured samples were products obtained at different extents of monomer conversion. The soap surrounding the latex particles was removed and the samples were dissolved in methanol and measured. The behavior of Dz in this system is understood by recalling that... 

Although they do not crystallize, polyvinyl acetates prepared at low temperatures apparently arc more syndiotactic since they yield more than usually crystalline polyvinyl alcohols by saponification. Monomers of high polarity such as vinyl trilluoraeetate by radical polymerization can form... 

Considering now reactions (5 a) and (5 b) (p. 176), it was found that the addition of monomers to macroradicals produced by chain transfer depends directly on the reactivity and polarity of both the radical and the monomer (203) and that the Q—e scheme of Alfrey and Price can be applied to these graft copolymerizations by chain transfer (227). In this way some unsuccessful attempts for grafting were interpreted, e. g. vinyl acetate on polystyrene and methyl methacrylate on polyvinyl acetate and polyvinyl chloride. 

Hayes established a list of some monomers in the order of decreasing activity towards grafting in emulsion vinyl chloride > vinyl acetate > styrene. Polymers can be listed in order of decreasing susceptibility to graft copolymerization, as follows polyvinyl chloride > polyacrylonitrile > polyvinyl acetate > polystyrene. 

Special properties of polyvinyl acetate are the very high hydrogen bonding and adherence to moist surfaces, and the self-plastization by absorption of less than 10% by weight of water. The absorption of water is sufficient to make the polyvinyl acetate flexible with natural body movement, pliable on moist tissue, permeable to water vapor and air, but not permeable to bacteria. Therefore, copolymers comprising polyvinyl acetate were synthesized for nonaqueous barrier dressings. Monomers were included to lightly crosslink the polyvinyl acetate. 

Vinyl acetate-butyl acrylate copolymers (0-100% butyl acrylate) were prepared by both batch and starved semi-continuous polymerization using sodium lauryl sulfate emulsifier, potassium persulfate initiator, and sodium bicarbonate buffer. This copolymer system was selected, not only because of its industrial importance, but also because of its copolymerization reactivity ratios, which predict a critical dependence of copolymer compositional distribution on the technique of polymerization. The butyl acrylate is so much more reactive than the vinyl acetate that batch polymerization of any monomer ratio would be expected to give a butyl acrylate-rich copolymer until the butyl acrylate is exhausted and polyvinyl acetate thereafter. 

The results showed that all batch polymerizations gave a two-peaked copolymer compositional distribution, a butyl acrylate-rich fraction, which varied according to the monomer ratio, and polyvinyl acetate. All starved semi-continuous polymerizations gave a single-peaked copolymer compositional distribution which corresponded to the monomer ratio. The latex particle sizes and type and concentration of surface groups were correlated with the conditions of polymerization. The stability of the latex to added electrolyte showed that particles were stabilized by both electrostatic and steric stabilization with the steric stabilization groups provided by surface hydrolysis of vinyl acetate units in the polymer chain. The extent of this surface hydrolysis was greater for the starved semi-continuous sample than for the batch sample. 

The vinyl monomer presumably would be CH2=CHOH, but this is the enol of acetaldehyde, which exists almost completely as CH3CH=0, and thus cannot be a vinyl monomer. Polyvinyl acetate can, however, serve as the precursor to polyvinyl alcohol ... 

Chemical modification of polymers continues to be an active field of research [1-5]. It is a common means of changing and optimising the physical, mechanical and technological properties of polymers [5-7]. It is also a unique route to produce polymers with unusual chemical structure and composition that are otherwise inaccessible or very difficult to prepare by conventional polymerisation methods. For example, hydrogenated nitrile rubber (HNBR) which has a structure which resembles that of the copolymer ethylene and acrylonitrile, is very difficult to prepare by conventional copolymerisation of the monomers. Polyvinyl alcohol can only be prepared by hydrolysis of polyvinyl acetate. Most of the rubbers or rubbery materials have unsaturation in their main chain and/or in their pendent groups. So these materials are very susceptible towards chemical reactions compared to their saturated counterparts. 

A gold-palladium catalyst which includes potassium acetate is very well established for the production of vinyl acetate monomer (VAM) from ethene, acetic acid and oxygen in selectivities as high as 96% (see Section 8.4). VAM is an important intermediate used in the production of polyvinyl acetate, polyvinyl butyral and a variety of other polymers, and the gold-catalysed process followed many years of industrially focused research and patent activity in a number of large industrial companies 39-43... 

Vinyl Acetate A monomer is a chemical building block used to manufacture a wide variety of polymers including polyvinyl acetate polyvinyl alcohol polyvinyl acetals ethylene vinyl acetate and ethylene vinyl alcohol. 

Polyvinyl Acetate occurs as a clear, water white to pale yellow, solid resin. It is prepared by the polymerization of vinyl acetate. After completion of polymerization, the resin is freed of traces of residual catalyst (usually a peroxide), monomer, and/or solvent by vacuum drying, steam sparging, washing, or any combination of these treatments. The resin is soluble in acetone, but it is insoluble in water. 

The industrial process for the vapor-phase manufacture of vinyl acetate monomer is quite common (Daniels, 1989) and utilizes widely available raw materials. Vinyl acetate is used chiefly as a monomer to make polyvinyl acetate and other copolymers. Hoechst-Celanese, Union Carbide, and Quantum Chemical are reported U.S. manufacturers. DuPont also currently operates a vinyl acetate process at its plant in LaPorte, Texas. To protect any proprietary DuPont information, all of the physical property and kinetic data, process flowsheet information, and modeling formulation in the published paper come from sources... 

Fig. 1.8. Molecular weight of polyvinyl acetate) in dependence on monomer concentration98). H202 (30% in HjO) 5g (O), 10g (A) methanol 95 g (O), 90 g (A) temperature 120 °C reaction time 4 h...

Copolymers are produced by the simultaneous polymerization of two or more dissimilar molecules. Examples include polyvinyl acetate, polyesters, and polyamides. Synthetic elastomers (such as SBR synthetic rubber, made from styrene and butadiene) are also copolymers. This pattern continues with the ter-polymers (such as acrylonitrile-butadiene-styrene (ABS)), which consist of three different monomers. 

Solution—polymerization of monomers dissolved in solvents in which the polymer products are also soluble Lower viscosity than bulk and better heat transfer and mixing direct application of solution less reactor fouling Smaller reactor capacity than bulk high separation cost often inflammable and toxic solvents lower molecular weights SBR, polyvinyl acetate, polystyrene, acrylics... 

Though in a strict sense vinyl polymers are all those made from vinyllij type monomers, CHj=CHX where X can be any substituent, the term isi used in industry and commerce as meaning mainly polymers made froii vinyl chlorides and from vinyl acetate. Included are also the copolymeti of these two monomers and those polymers which are derived from polyS vinyl acetate, namely, polyvinyl alcohol. and polyvinyl acetals. Polymers from vinylidene chloride, vinyl ethers, vinylpyrrolidone, and vinylcarbazit i ar also grouped loosely into this class. 

Polyvinyl Alcohol, e monomer of pol3rvinyl alcohol, vinyl alcohol (CHz=CHOH) is an unstable substance which, when formed by addition of water to acetylene, quickly isomerizes and forms acetaldehyde or ethylene oxide. The only way, therefore, 1 which polyvinyl alcohol can be obtained is by a hydrolysis of polyvinyl acetate. 

Polyrmjl Ethers. A number of pol3rvinyl ether homologues are available in commercial quantities. The monomers are usually prepared by decomposition of the lower polyvinyl acetates or by direct vinylation of alcohols by acetylene... 

Vinyl acetate was first described in a German patent awarded to Fritz Klatte and assigned to Chemishe Fabriken Grieshiem-EIectron in 1912. It was identified as a minor by-product of the reaction of acetic acid and acetylene to produce ethylidene diacetate. By 1925, commercial interest in vinyl acetate monomer and the polymer, polyvinyl acetate, developed and processes for their production on an industrial scale were devised. The first commercial process for vinyl acetate monomer involved the addition of acetic acid to acetylene in the vapor phase using a zinc acetate catalyst supported on activated carbon. This process was developed by Wacker Chemie in the early 1930s and dominated the production of vinyl acetate until the 1960s when an ethylene-based process was commercialized which supplanted the earlier acetylene technology [24]. 

More than half of vinyl acetate monomer is used in polyvinyl acetate emulsions and resins. The largest use of polyvinyl acetate emulsions is in adhesive emulsions. This is followed by use in copolymers to produce latex paints which have largely replaced solvent-based paints in developed countries. The adhesive emulsions are used in all types of consumer adhesives and glues used in the construction industry. 

Emulsions of polyvinyl acetate and polyalkyl acrylates have been used as tub caulking compositions, spackling compounds and as building sealants.22 Acrylic sealants which harden in the presence of powdered iron or copper meet Federal Specifications TT-S-00230C. 27 Liquid monomers, such as polyethylene glycol dimethacrylate and butyl alpha—cyanoacrylate have been used as room temperature curing sealants.22 22. 

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