Vulcameter Determination of Best Cure
Abstract Using a continuous cure curve to select a minimum number of stepped cures, it should be possible to vulcanize and test fewer sheets to determine best cure. This procedure is attractive for its potential of expediting the output of physical testing laboratories and especially for reducing the work load of stress-strain testing. Cure curves recorded with the Vulcameter approximated first-order reactions. Equations were derived to calculate the final force and rate constant from recorded force values without carrying the reaction to completion. A chart is suggested to assist in calculating the rate constant. Time for a given fractional rise in force depends only on the rate constant so that a chart for obtaining it is relatively simple. Experience and correlation with service performance in selecting best cures is emphasized. 95% rise times from Vulcameter curves were compared with conventionally selected best cures for a wide variety of compounds. Indications are that experience with the method might reduce the number of test-sheet cures to determine optimum stress-strain properties to one, two, or three depending upon the compound and the exactness required.