Vinyl alcohol homopolymer

Hydrolyzed ethylene—vinyl acetate copolymers [24937-78-8]> commonly known as ethylene—vinyl alcohol (EVOH) copolymers [25067-34-9], are usually used as extrusion resins, although some may be used in solvent-coating applications. As the ethylene fraction of these semicrystalline copolymers increases, the melting temperature decreases, the permeabilities increase, and the sensitivity to humidity decreases. The permeabilities as a function of polymer composition and humidity are shown in Figure 2. Vinyl alcohol homopolymer [9002-89-5] has a very low oxygen permeability in dry conditions however, the polymer is water-soluble. Trade names for these barrier polymers include Eval, Soamol, Selar OH, and Qarene. Table 6 lists the compositions... 

Poly( vinyl alcohol) is a versatile polymer with many industrial applications, and it may be the only polymer with an all carbon-carbon bond backbone that is truly biodegradable. The monomer is vinyl acetate, which is readily polymerized with free radical initiators to form poly(vinyl acetate), and the latter can be hydrolyzed either partially to prepare vinyl alcohol-vinyl acetate copolymers, or fully to prepare poly(vinyl alcohol). At high vinyl alcohol contents, the copolymers, and the vinyl alcohol homopolymer, are water soluble, and the aqueous solutions of these polymers find many applications for example, as adhesives or for coatings. The homopolymer and the very high vinyl alcohol copolymers are crystalline with melt transitions between 180 and 230 °C and glass transitions between 58 and 85 °C, depending on the vinyl alcohol content. The polymers can be melt processed to form molded plastics, fibers and films [36]. 

FIGURE 7.2 Monomer unit of poly(vinyl alcohol) homopolymer. 

Poly(vinyl alcohol) used to manufacture the poly(vinyl acetal)s is made from poly(vinyl acetate) homopolymer (see Vinyl polymers, vinyl alcohol polymers Vinyl POLYMERS, vinyl acetate polymers). Hydrolysis of poly(vinyl acetate) homopolymer produces a polyol with predominandy 1,3-glycol units. The polyol also contains up to 2 wt % 1,2-glycol units that come from head-to-head bonding during the polymeri2ation of vinyl acetate monomer. Poly(vinyl acetate) hydrolysis is seldom complete, and for some appHcations, not desired. For example, commercial PVF resins may contain up to 13 wt % unhydroly2ed poly(vinyl acetate). Residual vinyl acetate units on the polymer help improve resin solubiHty and processibiHty (15). On the other hand, the poly(vinyl alcohol) preferred for commercial PVB resins has less than 3 wt % residual poly(vinyl acetate) units on the polymer chain. 

Poly(vinyl acetate) emulsions are excellent bases for water-resistant paper adhesives destined for use in manufacturing bags, tubes, and cartons. Glue-lap adhesives, which require moderate-to-high resistance to water, exemplify this type. When routine water resistance is required, a homopolymer vinyl acetate emulsion containing a ceUulosic protective coUoid is effective for most purposes. Next effective are emulsions containing fuUy hydrolyzed poly(vinyl alcohol) as a protective coUoid, foUowed by those containing partiaUy hydrolyzed poly(vinyl acetate). 

PVA Formation Reaction. Poly(vinyl alcohol) is itself a modified polymer being made by the alcoholysis of poly(vinyl acetate) under acid or base catalysis as shown in Equation 1 (6.7). This polymer cannot be made by a direct polymerization because the vinyl alcohol monomer only exists in the tautomeric form of acetaldehyde. This saponification reaction can also be run on vinyl acetate copolymers and this affords a means of making vinyl alcohol copolymers. The homopolymer is water soluble and softens with decomposition at about 200°C while the properties of the copolymers would vary widely. Poly(vinyl alcohol) has been widely utilized in polymer modification because ... 

Note 2 Some polymers, are obtained by the chemical modification of other polymers such that the structure of the macromolecules that constitute the resulting polymer can be thought of as having been formed by the homopolymerization of a hypothetical monomer. These polymers can be regarded as homopolymers. A well-known example is poly(vinyl alcohol). 

CA s policy for naming acetylenic, acrylic, methacrylic, ethylenic, and vinyl polymers is to use the source-based method, and source-based representation is used to depict the polymers graphically thus, a synonym for polyethylene is polyethylene and not poly(1,2-ethanediyl) a synonym for polypropylene is polypropylene, and poly(vinyl alcohol) is named ethenol homopolymer although ethenol does not exist. Thus, these polymers are named and represented structurally by the source-based method, not the structure-based method. 

Such hydrophilic macromonomers (DPn=7-9) were radically homopolymer-ized and copolymerized with styrene [78] using AIBN as an initiator at 60 °C in deuterated DMSO in order to follow the kinetics directly by NMR analysis. The macromonomer was found to be less reactive than styrene (rM=0.9 for the macromonomer and rs=1.3 for styrene). Polymerization led to amphiphilic graft copolymers with a polystyrene backbone and poly(vinyl alcohol) branches. The hydrophilic macromonomer was also used in emulsion polymerization and copolymerized onto seed polystyrene particles in order to incorporate it at the interface. 

Polyvinyl alcohol (PVA) is a water-soluble polymer with a glass transition temperature, T, of 80 °C. Although its name implies a homopolymer stmcture, the structure of commercial PVA is a copolymer of vinyl alcohol and vinyl acetate as seen in Fig. 4.2. PVA is made by the incomplete hydrolysis of polyvinyl acetate... 

Since it is difficult to have poly(vinyl butyral) as homopolymer, a pyrogram for the copolymer with CAS 27360-07-2, which is poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), is shown in Figure 6.5.5. The pyrolysis was done in similar conditions to those used for other polymers previously discussed (see Table 4.2.2). The peak identification for the chromatogram displayed in Figure 6.5.5 was done using MS spectral library searches only and the results are given in Table 6.5.4. 

All of the product vinyl acetate is consumed in the production of homopolymer (one monomer) and copolymer products, among them poly(vinyl acetate) latices and resins, poly(vinyl alcohol) by postpolymerization hydrolytic removal of the acetate, and copolymers with vinyl chloride and ethylene. 

The calculated e(298K) 2.67 for poly(vinyl butyral) as a random copolymer containing 12% by weight of poly(vinyl alcohol), is in close agreement with the experimental value [8] of 2.69 for the low-hydroxyl grade of poly(vinyl butyral). If the presence of hydroxyl groups is neglected and the calculations are carried out for the homopolymer of poly(vinyl butyral), a dielectric constant of 2.42, which is much lower than the observed value, is calculated. 

Polystyrene is the name of a homopolymer made from the single monomer styrene. When the name of a monomer comprises two or more words, the name should be enclosed in parentheses, as in poly(methyl methacrylate) or poly(4-bromostyrene) to identify the monomer more clearly. This method can result in several names for a given polymer thus, poly(ethylene glycol) , poly(ethylene oxide) and poly(oxirane) describe the same polymer. Sometimes, the name of a hypothetical monomer is used, as in poly(vinyl alcohol) Even though a name like polyethylene covers a multitude of materials, the system does provide understandable names when a single monomer is involved in the synthesis of a single polymer. When one monomer can yield more than one polymer, e.g. 1,3-butadiene or acrolein, some sort of structural notation must be used to identify the product, and one is not far from a formal structure-based name. 

It should not pass unnoticed, however, that poly(vinyl alcohol), despite its immense industrial importance, is not a homopolymer, and is scarcely an ideal polymer for carrying out fundamental studies of steric stabilization. Indeed, its solution properties suggest that it may even be relatively atypical in its behaviour. 

A major fraction of the industrial homopolymer of vinyl acetate is converted to poly(vinyl alcohol). Since the monomer vinyl alcohol does not exist, poly-(vinyl alcohol) must be produced by hydrolysis or alcoholysis of a polymeric vinyl ester. 

The equilibrium between acetaldehyde and vinyl alcohol is overwhelmingly in the direction of acetaldehyde. In fact, monomeric vinyl alcohol evidently has not been isolated. Yet poly (vinyl alcohol) is an important item of commerce. It is manufactured by the controlled hydrolysis of polymeric vinyl esters. In fact, a major fraction of the industrial homopolymer of poly(vinyl acetate) is used to... 

Probably most industrial homopolymerizations of vinyl acetate are carried out by suspension processes, since the resulting beads are readily converted to poly(vinyl alcohol). This is the major reason for producing the homopolymer. Surprisingly little has been published about the suspension polymerization of vinyl acetate, despite the fact that Lindemaim [1] cites nearly 1100 references on the subject of vinyl acetate and approximately 2(K) references on the higher vinyl esters. 

Synonyms cas 9002-89-5 pva pvoh elvanol ethenol homopolymer vinyl alcohol polymer Polyvinylpyrrolidnone Homopolymer... 

This synthetic method has two steps the first step involves synthesising the polymer and the second includes modification with active groups. Some monomers generally used to form the backbone of homopolymers or copolymers include vinyl benzyl chloride, methyl methacrylate, 2-chloroethyl vinyl ether, vinyl alcohol and maleic anhydride. The polymers are then activated by anchoring antimicrobial groups, such as phosphonium salts, ammonium salts or phenol groups, via quaternisation, chloride substitution or anhydride hydrolysis. 

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