DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 3-4/1960 str. 53     <-- 53 -->        PDF

a) to examine some physical and mechanical properties of Silver and Black
Poplar-wood from the forest district Lipovljani,


b) to establish the differences between the physical and mechanical properties
of Silver and Black Poplar-wood.


From the sample trees were prepared 20 sample sections (bolts). These section
were taken at breast height of the sample trees. The lenght of these sections was


1.0 m. From these sample sections were made and examined 1313 specimens of Silver
Poplar-wood and 1.081 specimens of Black Poplar-wood. Measured and investigated
were the following physical and mechanical properties of Poplar-wood: annual-ring
width, specific gravity in air-dry and oven-dry state, nominal specific gravity, radial,
tangential and volume shrinkage; static bending strength, impact bending strength,
compressive strenght, modulus of elasticity, hardness by Janka and Brinell method,
and the moisture content of specimens.
On the basis of these investigations it is possible to draw the following conclusions:


1. The annual-ring width of Silver Poplar-wood (3.34 mm) is slightly greater
than the anual-ring width of Black Poplar-wood (1.69 mm). The difference in the
annual-ring width between Silver and Black Poplar-wood is significant.
2. The specific gravity in oven-dry state of Silver Poplar-wood (0.413 g/cm3) is
equal to that of Black Poplar-wood (0.412 g/cm3). In the analysis of the relation
between the annual-ring width and the specific gravity it was established the following:
the specific gravity of the wood possessing the annual-ring width up to 2 mm.
is greater in Silver Poplar-wood than in Black Poplar-wood; the specific gravity
of the Silver and Black Poplar-wood having the annual-ring above 2,0 mm in width
is are well-nigh equal. The greatest specific gravity of Silver and Black Poplar-wood
was found in annual-rings desplaying a width from 1,5 to 2,0 mm.
3. The radial, tangential and volume shrinkage of Silver Poplar-wood (4.4, 8.5,
13,7%) are some what smaller than the same properties in Black-wood % (4.7, 8.8,
14.4%). The differences in radial, tangential and volume shrinkage between the Silver
and Black Poplar-wood are not significant.
4. The static bending strength, impact bending strenght, compressive strength
and modulus of elasticity of Silver Poplar-wood (324 kg/cm5, 0,492 mkg/cm2,
422 kg/cm2 and 87727 kg/cm2) are slightly greater than the same properties in Black
Poplar-wood (317 kg/cm2, 0.450 mkg/cm2, 409 kg/cm2 and 82142 kg/cm2). The differences
in static bending strength, impact bending strength, compressive strength
and modulus of elasticity between the Silver and Black Poplar-wood are not significant.
The hardnes established by Janka-method in Silver Poplar-wood (280 kg/cm2)
is slightly lower than the property in Black Poplar-wood (312 kg/cm2). The difference
in hardness (Janka) between the Silver and Black Poplar-wood is significant.
Generally, it can be said, that the Silver and Black Poplar-wood is of small
density, moderate shrinkage, moderate compression and impact bending strength,
have low static bending strength, small elasticity as well as desplaying a mild
quality.