Abstract
Effects of alfalfa-intercropping and nanosilver-impregnation were studied here on the specific gas permeability of 10-year old Populus nigra var. betulifolia. Specimens were impregnated with a 200 ppm aqueous dispersion of silver nanoparticles under 250 kPa pressure; the results were then compared with the un-impregnated specimens. The size range of silver nanoparticles was 10 to 80 nm. After the initial measurement, specimens were kept in vaporized chamber for six months (43±2°C, and 80±3% relative humidity); permeability was measured every month. Results showed that maximum specific longitudinal gas permeability was observed in the nanosilver-impregnated inner-wood specimens of the treatment with alfalfa (1614,4 × 10-13 m3 m-1), and minimum permeability was found in the un-impregnated outer-wood specimens of the treatment without alfalfa (491,7 × 10-13 m3 m-1) before the vaporization. Vaporized chamber made permeability decrease permeability at the first phases because of the absorption of water vapors and the consequent swelling; however, due to the proliferation of pits and perforation plates by fungi and molds, permeability was eventually increased. Antibacterial property of silver did not significantly decrease the growth of molds and fungi in the nanosilver-impregnated specimens.
Highlights
Poplar, as a fast-growing species, can satisfy the growing needs for solid woods; it offers a quality raw material for wood-composite manufacturing factories because the end product will benefit from higher compression ratio
Longitudinal Gas Permeability Maximum specific longitudinal gas permeability was observed in the nanosilver-impregnated innerwood specimens of the treatment with alfalfa (1614.4 × 10-13 m3 m-1), and minimum permeability was found in the un-impregnated outer-wood specimens of the treatment without alfalfa (491,7 × 10-13 m3 m-1) before the vaporization (Figure 2)
Nanosilver impregnation increased specific gas permeability in all treatments; maximum increase was found in the inner-wood specimens of the treatment with alfalfa (95,8 % of increase)
Summary
As a fast-growing species, can satisfy the growing needs for solid woods; it offers a quality raw material for wood-composite manufacturing factories because the end product will benefit from higher compression ratio. Apart from natural species, special capabilities of poplar hybrids and clones can be useful too. These improved trees grown on intensively managed plantations reach saw-timber size and are harvested at a younger age (Dickmann 2006). In the recent decades, intercropping of poplar trees with different crops was gradually increased (Chaudhry 2003). Such an agroforestry system is suitable to encourage farmers to produce wood along with their annual crop harvests. Use of nitrogen-fixing plants is one of the methods for fertilizing plantation trees (Zobel 1992). Many industries need to know how permeable their wood is so that they could use permeability values in decision-making processes for impregnation, drying, filtration, as well as other purposes
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