| 1. |
- Aydemir, Deniz, et al.
(författare)
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Mechanical, Morphological and Thermal Properties of Nano-boron Nitride Treated Wood Materials
- 2016
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Ingår i: MADERAS. - 0717-3644 .- 0718-221X. ; 18:1, s. 19-32
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Tidskriftsartikel (refereegranskat)abstract
- Thermal instability is the one of the most important disadvantages of wood since it begins to decompose at a low temperature (˃110 °C). Many scientists, past and present, have conducted studies aimed at improving the thermal stability of wood. The aim of this study was to impregnate wood with nano-sized boron nitride (NBN) to improve its thermal stability and to investigate the changes in the properties of Scots pine, Ash and Iroco woods after the impregnation. The effects of the impregnation with NBN also were investigated on the heat-treated woods. The impregnation was conducted with using empty-cell method (the Rueping method) in a chamber under a pressure of 6 bars for 1 hr. Densities at 0% and 12% moisture content (MC), mechanical properties, color changes, thermal stability, and scanning electron microscopy (SEM/EDX) analysis were determined. The test results showed that the impregnation of wood with NBN increased generally the flexural strength and elasticity of modulus at bending, but the NBN impregnation decreased generally the compression strength except for ACI, ATWI, IC, and ICI. It was also determined that the changes in density and color were statistically different after the impregnation. According to the SEM/EDX results, deposits of nano-sized boron nitride were found inside the cell wall and on the pits. But the deposits were also determined in inside structure of the wood with EDX analysis. Thermal stability in T10% and T50% of wood was found to improve after the impregnation with NBN. TG/DTG and DTA values for some samples were found to fluctuate due to the heterogeneous dispersion of the NBN in the wood.
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| 2. |
- Blom, Åsa, 1977-, et al.
(författare)
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Some factors influencing susceptibility to discoloring fungi and water uptake of Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and Oriental spruce (Picea orientalis)
- 2013
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Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 8:2, s. 139-144
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Tidskriftsartikel (refereegranskat)abstract
- The heartwood and sapwood from Scots pine (PS), Norway spruce (PA), and Oriental spruce (PO) were tested for susceptibility to discoloring fungi and water uptake. In addition, annual ring width and density were measured. The methods used were Mycologg for testing growth of fungi and a modified version of EN 927-5 to investigate water uptake. For pine, the heartwood showed a lower water uptake and no discoloring fungi growing in the tests. The heartwood had a significantly higher density and smaller annual ring width than the sapwood. In PA the heartwood had significantly lower discoloration than sapwood. The total water uptake in g/m2 was significantly higher in sapwood, but not the calculated moisture content. As for wood properties, the density was significantly higher in sapwood compared to heartwood, although there were no differences in annual ring width. Regarding PO, differences in water uptake could be seen between sapwood and heartwood although the densities were similar. These results show that susceptibility to discoloring fungi and water uptake is hard to correlate to a single inherent property when looking at different wood species.
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| 3. |
- Sivrikaya, Huseyin, et al.
(författare)
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Changes in topochemistry and mechanical properties of Beech (Fagus orientalis L.) by natural fungus infestation
- 2022
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Ingår i: International Research Group on Wood Protection (IRG-WP) 29 May-2 June, Bled, Slovenia. - : IRG.
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Konferensbidrag (refereegranskat)abstract
- Beech is one of the major hardwood species in Europe. It is, however, highly susceptible to fungal attack both in the fresh state and during the storage. Understanding the alteration in chemical and mechanical properties of beech wood during the initial degradation state can lead to improved raw material utilization. Therefore, UV-microspectrophotometer (UMSP) and High-Performance Liquid Chromatography (HPLC) were employed to study the chemical changes in beech (Fagus Orientalis L.) samples infested naturally by white rot fungi. The mechanical properties of infested beech were also determined and compared with the sound wood. The UMSP showed an apparent degradation in the region of the S3 and the S2 layers. HPLC analysis illustrated that catechin was the main component both in sound and infested beech wood. Considerable reductions in the mechanical strengths, bending properties and compression strength, were also apparent due to infestation.
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| 4. |
- Sivrikaya, Hüseyin, et al.
(författare)
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Vacuum-heat treatment of Scots pine (Pinus sylvestris L.) wood pretreated with propanetriol
- 2022
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis Group. - 1748-0272 .- 1748-0280. ; 17:5, s. 328-336
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine sapwood was pretreated with two levels of propanetriol (20% and 40% w/w glycerol), and then subjected to vacuum-heat treatment (VHT) at 180°C and 200°C. The treated samples were examined with respect to their weight and volumetric changes, mechanical properties, colour changes, and dynamic water vapour sorption. The weight of the samples after VHT did not change with increasing the temperature, but it was increased in glycerol pretreated samples. Combination of glycerol pretreatment and VHT decreased the maximum swelling. Total colour change was significantly higher during VHT at a higher temperature, while no obvious trend observed in the samples pretreated with glycerol. Modulus of elasticity (MOE) and modulus of rupture (MOR) were not affected by solely VHT, but strongly decreased after glycerol pretreatment. The equilibrium moisture content (EMC) of the samples decreased by VHT. The glycerol pretreatment caused a reduction in EMC values at a relative humidity (RH) below 60%, but considerably increased the moisture sorption in the RH above 75%. VHT slightly reduced the sorption hysteresis compared to untreated wood, but an apparent reduction in hysteresis observed by glycerol pretreatment. This indicates that the flexibility of the wood cell wall polymers increases due to glycerol pretreatment, which results in decreased MOE and sorption hysteresis values.
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