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In 1983 the Canadian Conservation Institute (CCI) initiated a project to evaluate 27 poly(vinyl acetate) (P VA C) and 25 acrylic adhesives on the basis of pH, emission of harmful volatiles, flexibility/ strength and yellowing upon dark aging at room temperature and fluorescent light aging. Measurement of the pH of extracts showed that the PVAC adhesives were more acidic than the acrylic adhesives and that light aging tended to decrease the pH of both classes. The P VA C homopolymers generally were more acidic than the PVAC copolymers and many acrylic adhesives containing butyl acrylate were found to be neutral. The analysis of volatile compounds from the PVAC and acrylic adhesives showed that they emitted various ester and residual solvent compounds but only the PVAC adhesives released appreciable quantities of acetic acid. The results indicated that, after an initial curing period of several weeks, the evolution of acetic acid from the PVAC adhesives should not pose an acute hazard. In general, both PVAC and acrylic adhesives became less flexible after dark aging and the PVAC adhesives possessed more strength and less flexibility than the acrylics. PVAC copolymers displayed and retained more flexibility than PVAC homopolymers. ThePVAC adhesives yellowed approximately twice as quickly as the acrylic adhesives and light aging tended to make all the adhesives yellow more quickly than dark aging. The results of each test for each adhesive are tabulated for an overall view and assessment of the data.

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