Polyfvinyl formals

Table 14.1 Influence of structure variables on the properties of polyfvinyl formal)...

Polycondensation adhesives include phenolic and resorcinol resins and also urea -and melamine-formaldehyde resins. Adhesives of particularly high quality are obtained by combining phenolic resins with polyfvinyl formal) resins, nitrile rubber, or epoxy resins. Combinations such as these are often marketed as adhesive film. 

Japanese workers have developed fibres from polyfvinyl alcohol). The polymer is wet spun from warm water into a concentrated aqueous solution of sodium sulphate containing sulphuric acid and formaldehyde, the latter insolubilising the alcohol by formation of formal groups. 

Poly(vinyl formals) and poly(vinyl butyrals) are of importance in the coating industry. Commercial products differ in the degree of polymerization and acetalation, but especially in the residual polyfvinyl alcohol) content. 

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 polyfmethyl methacrylate) or poly(4-bromostyrene) to identify the monomer more clearly. This method can result in several names for a given polymer thus, polyfethylene glycol) , poly(ethylene oxide) , and poly(oxirane) describe the same polymer. Sometimes, the name of a hypothetical monomer is used, as in polyfvinyl 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 stiuctural notation must be used to identify the product, and one is not far from a formal structure-based name. 

The products are amorphous resins whose rigidity and softening point depend on the aldehyde used. Polyfvinyl butyral), with the larger side chain, is softer than poly(vinyl formal). Since the reaction between the aldehyde and the hydroxyl groups occurs at random, some hydroxyl groups become isolated and are incapable of reaction. A poly(vinyl acetal) molecule will thus contain ... 

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