Vinyl acetate vapor exposure

A coated surface-acoustic-wave (SAW) sensor capable of real-time, selective measurement of vinyl acetate vapor in the presence of several olefin and non-olefin cocontaminants is described. The coating film en loyed consists of the solid platinum-ethylene Ji-complex, trans-PtCl (ethylene)(pyridine). occluded in a polyisobutylene matrix. Exposure to vinyl acetate results in displacement of ethylene from the cott lex and formation of the vinyl acetate-substituted complex. Subsequent regeneration of the original reagent is possible by treatment with ethylene gas, in situ. A lower detection limit of 5 ppm of vinyl acetate is achieved for operation at 46 C. The industrial-hygiene applications of the sensor are discussed. 

The UV technology alluded to above holds out the promise of even more superior labels. In this process, ultraviolet cured inks are used as the printing medium. These are cured by exposure to industrial type UV mercury vapor lamps in either a non-inert system (air environment) or in an inert (oxygen-free) system. The result is excellent adhesion to vinyls, polyesters, polycarbonates, butyrates and acetates and a cured elongation of between 20 and 40% to avoid embrittlement of the substrate. Initial testing has exhibited little sign of degradation and excellent chemical resistance after three years of exterior exposure. Such UV labels as well as other techniques should be considered whenever use demands extended label performance. 

The selectivity of the sensor was tested by simultaneous exposure to VA and each of several other gases and vapors encountered with VA in industrial processes. The chemicals examined included ethyl acetate, methanol, methyl acrylate, methylmethacrylate, mesityl oxide and vinyl chloride. Table I summarizes the results for exposures at 40 C to 50 ppm of VA and each of the other chemicals. As shown, there was no measurable effect on the response to VA. With the exception of methyl acrylate, none of these confounds reacted with the conplex when exposed Individually. The response to 60 ppm of methyl acrylate alone was 10 Hz/mln which is about one-third that of VA at the same concentration. That methyl acrylate does not affect the response to VA during simultaneous exposure is remarkable since it indicates that the VA is exclusively favored in the con etition for reaction with the solid. This observation, coupled with the fact that the strongly-coordinating methanol does not increase the response to VA, is consistent with previous data (22) indicating an associative pathway for the reaction. 

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