Tree strips on agricultural production sites offer many economic, ecological and social advantages. However, the introduction of trees creates a transition zone between tree strips and crop land. ...Here, trees and crop plants compete for resources such as space, nutrients, water and light, which causes stress in the low‐competitive system. On the other hand, facilitation such as additional nutrient input through tree leaf litter and fine roots are possible. This study aims to provide indications for competition and benefits that can arise for plants growing in the transition zone of a temperate short rotation alley cropping agroforestry system (SRACS). Various climatic and plant‐growth parameters were investigated between 2013 and 2019 at different positions of an SRACS with fast‐growing poplars in northern Germany. Reduced yield of wheat, oilseed rape and silage maize close to the tree strip was associated with greater soil water tension in 30 and 60 cm soil depth due to the presence of poplar roots, reduced solar radiation due to tree shading and leaf litter coverage. In contrast, poplars growing in the outer rows produced more biomass than those in the inner rows due to the additional availability of space, light and nutrients taken from the crop field. Trees in the transition zone seem to be competitive with arable crops, but without effect on the average long‐term yield of arable crops.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Stable super-hydrophobic modification can extend wood service life and expand its application. Inspired by lotus leaf effects, this study proposed a new environmentally friendly strategy by using ...biomass-derived furfuryl alcohol (FA) and nano-particles based on organic-inorganic hybridization. The FA was pre-polymerized on wood surface followed by in situ growth of stearic acid modified nano-TiO2. The modified wood (PFT) behaved super-hydrophobic, and the water contact angle and rolling angle reached 157° and 3.2°. This was mainly because a micro-nano, coral-like and rough structure was fabricated on wood surface with hydrophobic furfural resin, suggested by SEM, AFM and FTIR results. The PFT presented prominent durable super-hydrophobicity after mechanical abrasion, tape peeling and acid destruction owing to the fixation effects from furfural resin on nano-TiO2. The dimensional stability was remarkably improved and the volumetric change after 24 h water absorption decreased by about 90 %. This was primarily because ① super-hydrophobic wood had low attraction to water molecules, ② most water paths were blocked by hydrophobic modifiers, ③ some cell walls were bulked and many sorption sites became inaccessible. Besides, the PFT exhibited excellent self-cleaning performances and improved surface hardness and thermal stability. Such stable and durable super-hydrophobic material may have long service life and meet demands for application under harsh environments.
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•A bio-inspired green strategy for creating superhydrophobic wood is proposed.•Synergies of furfural resin and nano-TiO2 are used for upgrading low-quality wood.•The fabricated superhydrophobic wood has excellent durability and stability.•The modified wood has improved hardness, dimensional stability and thermal stability.•Relation between wood property increase and structure is built for mechanism analysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The primary issues restricting fast-growing wood utilization in buildings are its low dimensional stability and lack of strength grading. Thermal treatment has been shown to improve wood dimensional ...stability while decreasing certain mechanical parameters. This study was aimed to optimize the thermal treatment for fast-growing poplar wood to determine its impact on the wood strength class from the perspective of structural applications. Seven temperature levels between 20 and 210 °C and 2 h heating duration were used to thermally treat fast-growing poplar wood, which was then subsequently investigated for chemical composition and color change, as well as mechanical properties, such as parallel-to-grain bending, tensile, compressive (fc,0), shear strength (fv), modulus of elasticity (M0), and perpendicular-to-grain tensile strength. In addition, characteristic values were derived to provide an initial indication of design values. Thermal treatment resulted in hemicelluloses degradation, which darkened the color and reduced strength according to chemical composition and infrared spectroscopic analyses. In general, mechanical properties decreased with temperature, except for fc,0 and M0, which increased with temperature (≤180 °C) and followed by a decrease at ≥ 190 °C. The strength class of heat-treated wood depended on the smaller values of M0 and fv. M0 determined the strength class of native and heated wood to be ≤ 180 °C and fv at ≥ 190 °C. Thermal treatment in the region of 170–180 °C was a practical approach to improving wood properties in view of their structural use. Results of this study provided a basis for developing a design guide for structural uses of thermally-treated poplar wood.
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•Variations in mechanical properties were attributed to thermal degradation of chemical composition.•The strength class of heated wood exposed to a broad variety of temperatures was determined.•The 170–180 °C was recommended to be used in treating poplar wood in view of structural applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fast-growing poplar with the dominant characteristic of short rotation plantation offers a potential solution to the growing market demand for wood. However, its practical applications are limited ...due to shortcomings such as high flammability and poor dimensional stability. To address these issues, this study introduced a facile impregnation process involving the in-situ polymerization of bio-based furfuryl alcohol (FA) and ammonium phytate (AMP) to enhance the flame retardancy and dimensional stability of poplar. The biomass content was higher than 95% for this impregnation solution. The thermal stability experiments revealed that the residual char mass of AMP/FA-wood at 800°C increased by 305% compared to unmodified poplar. Moreover, the AMP/FA-wood demonstrated superior flame retardancy, achieving UL-94 V-0 rating and a high limiting oxygen index of 36.3%. Additionally, it exhibited decreased heat release and total smoke production of 48.9% and 79.8%, respectively, in comparison to unmodified poplar wood. The impressive flame retardancy of AMP/FA-wood was ascribed to the incorporation of AMP through the nitrogen-phosphorus synergistic intumescent mechanism. Notably, the in-situ polymerization of FA during the modification process, the AMP/FA-wood displayed exceptional dimensional stability which was confirmed by the moisture content, anti-swelling efficiency, and water absorption tests. Hence, AMP/FA-wood with its excellent flame retardancy, thermal stability, and dimensional stability, holds promise as a reliable wood supply for various applications such as furniture, home decor, construction, and building.
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•Phytic acid (PA) reacted with urea to synthesize the N/P flame retardant ammonium phytate (AMP).•AMP and furfuryl alcohol (FA) resins were utilized to modify fast-growing poplar wood by impregnation.•The impregnation solution had a high in biomass content and was environmentally friendly.•The AMP and FA modified wood significantly increased flame retardancy and dimensional stability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Dowel joint is a commonly used connection method in furniture products, building construction etc. because of its production convenience and low cost. The quantitative effect of dowel dimension, ...dowel position, loading distance on bending moment capacity was studied in this paper. The results showed that neutral line position keeps almost steady with various dowel spaces for two-pin joint. On the basis of the discovery, an analytic model was constructed to predict bending moment capacity of joint in terms of two different failure patterns: dowel withdrawal and dowel rupture. The theoretical models have shown a good agreement with measured results. Dowel space has positive effect on the bending moment capacity while the impact of loading distance can be neglected. But the top dowel, rather than bottom dowel, plays a critical role in deciding joint moment capacity. Increasing dowel diameter and length, fortifying dowel rupture and withdrawal strength, enlarging dowel space, or moving bottom dowel far away from the bottom edge will promote the joint performance. But it should be noted that ratio of dowel diameter to length equal to two times that of dowel withdrawal strength to dowel tensile strength gives the optimized joint parameters
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Thermal modification has been commonly perceived to improve wood dimensional stability, but decreases certain main mechanical properties. This research aimed to optimize thermal modification for ...poplar wood to determine its impacts on strength class for potential structural use. In this study, poplar wood was thermally modified at temperatures between 160 and 210 °C and 2 h duration, after which the chemical composition and mechanical properties were determined. The results showed thermal modification led to hemicelluloses degradation, which served as the main reason for strength reduction. The main mechanical properties of thermally-modified wood decreased with temperatures, except for compressive strength and modulus of elasticity, which increased with temperature (≤180 °C) and was followed by a reduction at ≥190 °C. The strength class of thermally-modified wood was dependent on the smaller value of modulus of elasticity and shear strength. Thermal modification at 180 °C was shown to be practical in improving wood properties for structural use.
•The cause of variations in heated poplar's strength was discovered.•Strength class of heated poplar at high temperatures was determined.•A suitable modification temperature was recommended in view of structural use.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fast-growing poplar with characteristics of fast growth, convenient processing, and strong adaptability is widely planted all over the world, but it is difficult to be directly used as structural ...timber due to its loose fibers and low strength. In order to enhance mechanical properties of fast-growing poplar, a new type of steel plate reinforced glulam fast-growing poplar is developed. Nine columns are tested including one fast-growing poplar column, two glued-laminated timber (glulam) columns and six steel plate reinforced glulam columns. The influencing factors include the steel plate thickness and eccentricity. Based on test results, axial stiffness, failure mode, load-displacement and load-strain relationships were investigated. Test results indicate that ultimate load and axial stiffness of steel plate reinforced glulam columns were respectively increased by 134.5–177.5% and 168.5–244.1% compared to fast-growing poplar column. With the increase of steel plate thickness and decrease of eccentricity, ultimate load increased by 10.9–18.3% and 27.2–92.3%, respectively. It was found that steel plate thickness and eccentricity have great impacts on bearing capacity of steel plate reinforced glulam columns. In addition, bearing capacity equation for steel plate reinforced glulam columns was established and test results coincide quite well with calculated results with difference of less than 5%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Surface densification & impregnation boosted the overall performance of wood.•Modified wood achieved a V-0 grade of fire resistance.•Surface hardness and wear resistance respectively improved by ...132% and 22%.•Flexural and impact strength increased by 52% and 48%, respectively.•Modified wood with low density exhibited excellent dimensional stability.
It is difficult to significantly improve the mechanical performance and fire-resistance of fast-growing wood without increasing its density. In this study, a modified poplar wood (USD-RA-W) with low-density, high dimensional stability, high mechanical strength, and fire resistance was successfully prepared by unilateral surface densification assisted with the impregnation of waterborne acrylic resin (WAR)/ammonium phytate (APA). The flexural and impact strength values of USD-RA-W increased by 52% and 48%, respectively, compared to the control samples (C-W). The surface hardness and wear resistance of USD-RA-W were also significantly improved, with a 132% increase in hardness and a 22% reduction in weight loss relative to C-W. The improvement in mechanical properties is attributed to the synergistic effects of surface densification and impregnation modification of APA-doped acrylic resin. The in-situ-cured resin network provides excellent dimensional stability by fixing the spring-back of the densified surface of the material. USD-RA-W shows significantly improved fire retardancy due to the introduction of bio-based APA. UL-94 analysis results show that the fire-retardant grade of the USD-RA-W passed V-0 and the limited oxygen index reached 50%. Cone calorimeter test results indicate that the total heat release rate and smoke release rate of the experimental group decreased by 32% and 77%, respectively, while the char residue reached 41%. A simple and green physic-chemical method for the preparation of high-performance USD-RA-W was established in this study. The proposed treated wood may be applicable in structural building materials and interior decoration fields.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Bending-shear test of steel reinforced fast-growing poplar glulam was carried out.•The failure modes of steel reinforced fast-growing poplar glulam beams with different shear span ratios were ...flexural failure or interlaminar shear failure.•The steel reinforced fast-growing poplar glulam improved bearing capacity, stiffness and ductility.•Theoretical models were proposed to calculate flexural and shear capacity.
A new type of steel reinforced fast-growing poplar glulam beam was proposed to improve the mechanical properties of fast-growing poplar glulam beam in this paper. 8 specimens were tested by a four-point bending method. The test was considered two factors: material properties (fast-growing poplar glulam beam, steel reinforced fast-growing poplar glulam beams) and shear-span ratios (1.5, 2, 2.5, 3, 3.5, 4, 6). Test results showed that: (1) The failure mode of the fast-growing poplar glulam beam was interlaminar shear failure. (2) When shear-span ratio (a/h) was between 3 and 6, the failure modes of the steel reinforced fast-growing poplar glulam beams were flexural failure; when shear-span ratio (a/h) was between 1.5 and 2.5, the failure modes of all steel reinforced fast-growing poplar glulam beams were interlaminar shear failure. (3) Compared with the fast-growing poplar glulam beam, the ductile coefficient, the ultimate load, the ultimate displacement and the initial bending stiffness of the steel reinforced fast-growing poplar glulam beams was increased by 92%, 34.7%, 64.7% and 60.9%, respectively. (4) With the increase of a/h, the ultimate load and the initial bending stiffness of the steel reinforced fast-growing poplar glulam beams decreased gradually, while the ultimate displacement and the ductile coefficient decreased first and then increased. Finally, the theoretical model is respectively proposed to estimate the flexural and shear capacity of the steel reinforced fast-growing poplar glulam beams.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Poor dimensional stability restricts the commercial utilization of fast-growing wood. In this study, fast-growing poplar (
) was treated by removing hemicellulose with hydrothermal treatment and ...impregnating alkali lignin via full-cell process, synergistically, for enhanced dimensional stability. After modification, hydroxyl groups were reduced in hemicellulose removed wood (DHC), alkali lignin was observed to fill in the cell lumens of vessels and wood fibers in the impregnated wood (AL) and in the wood modified by hemicellulose removal with alkali lignin impregnation (DHCAL). Compared with untreated wood, the volumetric swelling ratio of DHC and AL decreased by 11 % and 21 % under relative humidity (RH) of 89 %, respectively. The volumetric swelling ratio of DHCAL decreased by over 50 %, indicating a positive synergistic effect. The combination of hemicellulose removal and alkali lignin impregnation treatment improved the dimensional stability of wood significantly by reconstructing wood chemical components with various levels of hygroscopicity. This work could meaningfully contribute to the efficient utilization of fast-growing wood and promote the added value of industrial alkali lignin.
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