Pretreatment with Ultrasonic Energy—Its Effect Upon Volumetric Shrinkage of Redwood
AbstractRedwood heartwood samples 1.2 inches in cross section were subjected to ultrasonic irradiation prior to oven-drying. There was a small but consistent reduction in volumetric shrinkage due to the pretreatment when the test cell was subjected to continuous vacuum during irradiation. It is believed that cavitation of the wood liquid was responsible for the effect. However, since the sample moisture contents were considerably less than the maximum moisture content for redwood, the effect was evidently due to something other than the elimination of Tiemann liquid tension stress. It is suggested that the denaturing is of the kind, but not to the extent, of that believed to occur in the freezing of wet redwood.
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