Determination of vinyl acetate in vinyl chloride-acetate copolymers

Determination of combined vinyl acetate in vinyl acetate-vinyl chloride copolymers by an isotope dilution-derivative method

“…Accuracy of the method is determined principally by the extent of hydrolysis of the ace- tate groups and the chemical and radiochemical purity of the derivative. Although refluxing in both acetone (6,(8)(9)(10) and dioxane (4, 5) has been used for hydrolysis, the complete miscibility of these solvents with water is disadvantageous for separation of the major fraction of the sodium acetate from hydrolyzed polymer by aqueous extraction.…”

“…MEK is only partially miscible with water and can therefore be employed with this extraction step. Hydrolyses were performed initially in sealed tubes to prevent possible volatilization of methyl acetate formed by transesterification (8). Subsequent analyses in stoppered flasks showed, however, that no loss of ester occurred.…”

“…An alternative approach is direct titration of the alkaline hydrolyzate successively with standard acid and silver nitrate solutions (7). Conductometric titration with standard sodium hydroxide solution after adding an excess of hydrochloric acid to the hydrolyzate (6) has been employed, as has potentiometric titration of the mixture of acetate and excess alkali used for hydrolysis (8)(9)(10). Although these instrumental methods require only a single titrant, the need to establish two end points is a common drawback affecting precision.…”

Coatings

“…Infrared spectrometry was used (135) to determine the poly (vinyl acetate) content of the copolymer with vinyl chloride; the calculation was based on absorbance intensities of the bands at 5.74 microns and 7.02 microns. A potentiometric method was also described (128) for measuring the vinyl acetate in a copolymer with vinyl chloride. In this method, the sodium acetate formed by saponification of the vinyl acetate was titrated with hydrochloric acid.…”

“…Three different procedures were described by Sciarra (128) for determining the volatile content of aerosol products. A rapid total solids procedure (97) was based on the use of a hot-wire drying element in place of the usual oven.…”