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SynopsisA kinetic model based on the free volume theory has been proposed for the polymerization of styrene. The model, which is capable of describing the course of polymerization in both bulk and solution, accounts for diffusion-controlled termination and propagation and gives a limiting conversion.

or less, which indicates the presence of few long-chain branches. No long-chain branches are found in PVA samples that have a degree of hydrolysis higher than 80 mol%. The number of short-chain branches is identical to the mole percent of short-chain branches generated during the formation of the poly(vinyl acetate) in the range of 0.12-0.17 mol% (65).

Poly(vinyl alcohol) is a highly crystalline polyhydroxy polymer produced by the hydrolysis of poly(vinyl acetate) because the vinyl alcohol monomer is not available. The polymer is water‐soluble and possesses excellent tensile strength, abrasion resistance, and superior oxygen‐barrier properties. PVA has excellent emulsification and protective colloid properties. Solvent, oil, and grease resistance are matched by few other polymers. Poly(vinyl alcohol) undergoes chemical reactions in a manner similar to other secondary polyhydroxy alcohols, and is fully biodegradable. The polymer is considered a nonhazardous material according to the American Standard for Precautionary Labeling of Hazardous Industrial Chemicals. Industrial applications of poly(vinyl alcohol) are all based on and limited by the use of water solutions. The polymer is not considered thermoplastic as the degradation temperature is below the melting point. Poly(vinyl alcohol) is commercially available in granular and powdered form. Grades include both fully hydrolyzed and partially hydrolyzed products. A wide variety of molecular weight and hydrolysis is commercially available. Major end uses include textile sizing, adhesives, protective colloid for emulsion polymerization, paper coating, cement and mortar additive, poly(vinyl butyral), fibers, and films.

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