ULTRASONIC VELOCITY AND MOISTURE-CONTENT IN WOOD .3. ULTRASONIC VELOCITY AND AVERAGE MOISTURE-CONTENT IN WOOD DURING DESORPTION .2. DURING DESORPTION FROM A WATER-SATURATED CONDITION ENGLISH, JAPANESE
A. Mishiro, ULTRASONIC VELOCITY AND MOISTURE-CONTENT IN WOOD .3. ULTRASONIC VELOCITY AND AVERAGE MOISTURE-CONTENT IN WOOD DURING DESORPTION .2. DURING DESORPTION FROM A WATER-SATURATED CONDITION ENGLISH, JAPANESE, Mokuzai Gakkaishi, 42(10), 1996, pp. 930-936
The relationship between ultrasonic velocity in the radial and longitu
dinal directions and the average moisture content in wood during desor
ption from a water-saturated condition was examined. The species used
were sugi (Cryptomeria japonica D. Don), hinoki (Chamaecyparis obtusa
Endl.), beisugi (Thuja plicata D. Don), agathis (Agathis sp,),buna (Fa
gus crenata Blume), makanba (Betula maximowicziana Regel) and shioji (
Fraxinus commemoralis Koidz.) and their dimensions for measurements in
the radial directions differed from that in the longitudinal directio
ns. All faces except the measuring faces of specimens were coated with
parafilm so that moisture evaporation took place from one direction.
During desorption from water-saturated conditions, the patterns of ult
rasonic velocities versus average moisture content in the radial and l
ongitudinal directions varied very much with species, and they could b
e divided into three groups. In the first group in the radial directio
ns, ultrasonic velocities decreased from water-saturations to about av
erage moisture contents of 40%; after that, they increased quickly as
average moisture contents decreased. The species of each group did not
correspond in the radial and longitudinal directions. The pattern of
ultrasonic velocity versus average moisture content on a graph in the
radial direction during desorption from water-saturated conditions can
be explained by the law of composites for their moisture distribution
.