Hydrothermal treatment of bamboo and its effect on nano-mechanic and anti-mildew property

Bamboo is one of the most promising biomass materials in the world. However, the poor anti-mildew property and poor dimensional stability limits its outdoor applications. Current scholars focus on the modification of bamboo through heat treatment. Arc-shaped bamboo sheets are new bamboo products for special decoration in daily life. In this paper, we reported pressure-steam heat treatment and explored the effect of pressure-steam on the micro-structure, crystallinity index, anti-mildew, chemical composition, physical properties, and mechanical properties of bamboo via X-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), wet chemistry method and nanoindentation (NI). Herein, saturated-steam heat treatment was applied for modified moso bamboo for enhancing the anti-mildew properties and mechanical properties of moso bamboo. Results showed that with the introduction of saturated steam, the content of hemicellulose and cellulose decreased, while the lignin-relative content increased significantly. The anti-mildew property of moso bamboo was enhanced due to the decomposition of polysaccharide. Last, the modulus of elasticity and hardness of treated moso bamboo cell walls were enhanced after saturated-steam heat treatment. For example, the MOE of the treated moso bamboo cell wall increased from 12.7 GPa to 15.7 GPa. This heat treatment strategy can enhance the anti-mildew property of moso bamboo and can gain more attention from entrepreneurs and scholars.

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Pressure-Steam Heat Treatment-Enhanced Anti-Mildew Property of Arc-Shaped Bamboo Sheets

Sustainable pulpwood production from fast-growing tree plantations is needed for pulp and paper industries. To increase the pulpwood production efficiency, the anatomical characteristics and derived-wood properties of 75 trees from 15 half-sib families of Eucalyptus camaldulensis Dehnh. planted in Thailand were investigated, and then the family was classified by suitability of wood as raw material for pulp and paper products using principal component analysis and clustering. The mean values of vessel diameter, vessel frequency, fibre diameter, fibre lumen diameter, and fibre wall thickness at 2 cm from the cambium were 128 µm, 16 no./mm2, 11.1 µm, 7.1 µm, and 1.88 µm, respectively. In addition, the Runkel ratio, Luce’s shape factor, flexibility coefficient, slenderness ratio, solids factor, and wall coverage ratio (i.e., derived-wood properties) were 0.53, 0.42, 0.64, 85.3, 68 × 103 µm3, and 0.34, respectively. Significant differences in fibre diameter, fibre lumen diameter, and Runkel ratio were found among families. Although significant differences among families were not found for other anatomical characteristics and derived-wood properties, the p-values obtained by an analysis of variance test ranged from 0.050 to 0.088. Based on the results of a principal component analysis and cluster analysis, 15 families were classified into four clusters with different expected pulp and paper characteristics. The suitability of wood from E. camaldulensis half-sib families for pulp and paper can be evaluated by principal component analysis using anatomical characteristics and physical properties as variables. Based on the results, desirable pulp and paper quality may be obtained through the selection of families from this species.

https://www.mdpi.com/1999-4907/12/1/31/pdf

Selection of Eucalyptus camaldulensis Families for Sustainable Pulpwood Production by Means of Anatomical Characteristics

Secondary xylem maturation evaluated by modeling radial variations in anatomical characteristics and wood properties of Shorea macrophylla (De Vr.) Ashton planted in Sarawak, Malaysia

Modeling of radial variations in wood properties and comparison of juvenile and mature wood of four common conifers in Mongolia

We examined the physical and mechanical properties of wood in Siberian larch (Larix sibirica) trees that grow naturally in five Mongolian provenances (Khentii, Arkhangai, Zavkhan, Khuvsgul, and Selenge) and the geographic variations between them. Five trees with stem diameters of 20 to 30 cm at 1.3 m above ground were collected from each provenance. The mean values of the modulus of elasticity (MOE), modulus of rupture (MOR), compressive strength parallel to grain (CS), and shearing strength (SS) ranged from 7.03 to 9.51 GPa, 79.8 to 103.9 MPa, 46.3 to 51.1 MPa, and 10.4 to 13.0 MPa, respectively. Significant differences were found in radial and tangential shrinkage, MOE, MOR, and SS in wood among the five provenances. In addition, juvenile wood had inferior physical and mechanical properties in comparison to mature wood within and among provenances. Furthermore, there were significant differences in all examined properties, except for CS, in mature wood among the five provenances. Higher correlation coefficients were also obtained in mature wood among all mechanical properties, except for SS.

Physical and mechanical properties of wood and their geographic variations in Larix sibirica trees naturally grown in Mongolia.

Abstract To clarify inheritance of static bending properties in relation to elastic and plastic regions, air-dry density, microfibril angle of the S2 layer in latewood tracheid (MFA), and static bending properties (modulus of elasticity [MOE], modulus of rupture [MOR] and bending work) were examined for juvenile wood of 18 full-sib families in 20-year-old Cryptomeria japonica. Heritability of all traits ranged from 0.12 (bending work) to 0.51 (air-dry density). Based on the results from principal component analysis (PCA) and cluster analysis, the families were classified into four groups with different types of load-deflection curves, suggesting that both elastic properties and deflection in plastic region differed among families. Furthermore, families included in a group were produced from specific parents, suggesting that deflection in plastic region as well as elastic property is inheritable. It can be concluded that mating parents may affect elasticity and plasticity of offspring.

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Inheritance of static bending properties and classification of load-deflection curves in Cryptomeria japonica

Abstract To promote solid wood production, the diameter at breast height, height, stress-wave velocity, surface-released strain, basic density and compressive strength parallel to the grain were measured for 10 half-sib families of 12-year-old Eucalyptus camaldulensis Dehnh. trees growing in Thailand. Based on the results, growth rates, correlations among measured properties, radial and among-family variations of wood properties, and their repeatability were evaluated. Diameter at breast height, height, and wood volume were exponentially increased at initial stage, and then gradually increased toward to 12 years after planting. The maximum current annual increment and mean annual increment in wood volume showed at age of 8 and 11years old, suggesting that rotation period for optimum productivity may be ranged from 8 to 11 years old. Wood with stable properties was found greater than 6 cm from the pith. These results indicate that 12-year-old E. camaldulensis trees had already reached the maturation stage. No significant correlations were found between growth characteristics and wood properties. Significant variances in the height, stress-wave velocity, and basic density were found among the 10 families. The F-values and repeatability of the wood properties in the outer wood were higher than those in the inner wood. These results indicate that the properties of the outer wood are closely related to genetic factors. Thus, to obtain superior E. camaldulensis trees for solid wood production, the family selection should be conducted using the outer wood of aged trees.

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Repeatability of growth characteristics and wood properties for solid wood production from Eucalyptus camaldulensis half-sib families growing in Thailand

Haruna Aiso

Papers

Physical and mechanical properties of wood and their geographic variations in Larix sibirica trees naturally grown in Mongolia.

Inheritance of static bending properties and classification of load-deflection curves in Cryptomeria japonica

Repeatability of growth characteristics and wood properties for solid wood production from Eucalyptus camaldulensis half-sib families growing in Thailand