Transparent wood was prepared from basswood (Tilia) subjected to various degrees of delignification prior to its polymer impregnation. The chemistry and surface morphologies of wood samples were ...evaluated. The optical properties such as surface color, optical transmittance and optical haze of natural wood and each transparent wood product and their mechanical properties were monitored in order to better understand the influence of delignification. Experimental results indicated that the lightness of transparent wood increased with delignification, while the redness and yellowness decreased. The transparent wood exhibited a maximum optical transmittance of 61% at 800 nm with 9% lignin content and also possessed enhanced visual optical haze at different levels of delignification. In addition, transparent wood had a higher tensile strength than natural wood and displayed a maximum tensile strength up to 171.4 MPa with 15% lignin content among these transparent wood products pretreated with delignification. Our findings offer a view into how transparent wood can be produced to fit certain levels of optical and mechanical properties.
•β-crystal of polypropylene wax exhibited better UV resistance compared to α-crystal.•When the content of WBG-II is 0.3 wt.%, the UV resistance of the wax coating is optimal.•During UV irradiation, ...the β-crystal of the wax coating hinders oxygen penetration.
In China, beeswax is commonly used to protect hardwood surfaces through hot waxing, and is widely utilized in wood furniture and buildings. However, beeswax, with its low melting point and high cost, is prone to being destroyed and falling off, and has a short-term protective effect on wood under ultraviolet (UV) light. Polypropylene wax (PPW), with its low cost and high melting point, holds potential for application in wood protection. The introduction of maleic anhydride enhanced the combination of PPW and wood, resulting in excellent surface properties. Additionally, the β-nucleating agent (WBG-II) induced PPW to form β crystal structure, further enhancing the UV barrier property of the wax coating. After UV irradiation, the surface properties of the hot-waxed wood using the modified polypropylene wax exhibited minimal changes, including color, adhesion, hydrophobicity, and surface roughness. The chemical structure, crystalline structure, and surface morphology were analyzed by FTIR, XRD, and SEM to reveal the photodegradation mechanism of the surface wax coating. The results demonstrated that the co-modification of polypropylene wax by maleic anhydride and WBG-II has a positive effect on the long-term protection of wood substrate, providing a reference for wood protection, particularly for dark and precious wood, and helping to reduce deforestation.
Herein, an activated wood surface rich in CHO groups was constructed by spraying a sodium periodate aqueous solution on a natural wood surface. Besides, microcrystalline cellulose was functionalized ...to obtain aminated cellulose, which was dissolved in an aqueous solution and used as a specific adhesive. Subsequently, an ultrastrong wood bonding interface was co-constructed with the activated wood surface and aminated cellulose, which was formed by a chemical covalent reaction between aldehyde groups at the activated wood interface and amino groups on aminated cellulose. The dry, hot-water, and boiling-water lap shear strengths of the plywood specimens were 1.47, 1.07, and 1.08 MPa, respectively. The boiling-water strength of the plywood made from the activated wood surface achieved increased to 1.08 MPa from 0 MPa of the plywood constructed on the nonactivated wood surface. The chemical crosslinking reaction and bonding mechanism between the adhesive and activated wood surface were clarified by density functional theory calculations, attenuated total reflectance–Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results showed that chemical bonding (aminal NCN and imine CN) at the bonding interface played an important part in improving the water resistance and bonding strength. This work provides new concepts for designing durable and moisture-resistant wood products.
Schematic diagram for the design and development of superstrong wood bonding via chemical bond between activated wood surface and aminated cellulose. Display omitted
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•An activated wood interface equipped with epoxy groups was prepared.•A quinone-amine-epoxy cross-linked network was constructed.•The adhesive exhibits excellent bonding strength and ...water resistance.•This work offers a novel strategy for producing high-performance materials.
Biomass adhesives have long been a subject of widespread concern and study due to their cost-effectiveness and minimal environmental impact. In this study, an activated wood surface with epoxy groups (AWI) was created by uniformly applying 3-glycidoxypropyltrimethoxysilane (KH560) onto poplar veneer. Then the aminated xylan-oxidized tannic acid adhesive (2AX-OTA) was prepared based on the Schiff base reaction between the quinone of oxidized tannic acid (OTA) and the amine group of aminated xylan (AX). Eventually, the high-performance bonding interface was co-built by 2AX-OTA and AWI. The dry bonding strength of 2AX-OTA-AWI plywood achieved 3.86 MPa, while the wet bonding strength was measured at 2.41 MPa and 2.15 MPa after immersion in hot (63 °C)/boiling water for 3 h. FT-IR, 13C NMR, and XPS chemical analyses demonstrated that a triple cross-linked network structure of the bonding interface was co-constructed by imine covalent chain bridges and epoxy-amine network. This triple cross-linked network structure plays a crucial role in enhancing water resistance. This study presents a novel approach to designing multi-cross-linked networks for the synthesizing of eco-friendly and high-performance bio-based adhesives.
The goal of this work was to understand and model the combined effect of time, geographical location, and exposure on the physical-chemical mechanisms of wood weathering in structures. Series of ...wooden samples were exposed to natural weathering in seven locations varying in climatic conditions, including Italy and north Germany. The set of samples was exposed for 4 years, collecting representative samples each year. Four exposure directions (north, south, east, and west) were investigated. Measurements of samples included: photogrammetry, near and mid infrared spectroscopy, color, gloss, roughness, and elemental composition (x-ray fluorescence spectroscopy). Results showed that the surface degradation mechanisms caused by weathering were affected by the site of exposure. The wood samples weathered in the Italian sites, in Udine and Macerata, were most degraded. The most significant changes were observed in samples exposed to the south direction. The original algorithm for calculation of "the weathering indicator", by merging the multi-sensor data and linking these to the surface performance indicators was developed. Finally, the subjective visual assessment by the expert person was compared with parameters obtained by measuring the weathered surfaces with various sensors. A good correspondence between weathering indicator W
ind
and subjective quality index was established.
This paper reviews the discrepancy between predicted and measured energy use in non-domestic buildings in a UK context with outlook to global studies. It explains differences between energy ...performance quantification and classifies this energy performance gap as a difference between compliance or performance modelling with measured energy use. Literary sources are reviewed in order to signify the magnitude between predicted and measured energy use, which is found to deviate by +34% with a standard deviation of 55% based on 62 buildings. It proceeds in describing the underlying causes for the performance gap, existent in all stages of the building life cycle, and identifies the dominant factors to be related to specification uncertainty in modelling, occupant behaviour and poor operational practices having an estimated effect of 20-60%, 10-80% and 15-80% on energy use respectively. Other factors that have a high impact are related to establishing the energy performance target, impact of early design decisions, heuristic uncertainty in modelling and occupant behaviour. Finally action measures and feedback processes in order to reduce the performance gap are discussed, indicating the need for energy in-use legislation, insight into design stage models, accessible energy data and expansion of research efforts towards building performance in-use in relation to predicted performance
This study aims to determine the optimal CNC (Computer Numerical Control) machining conditions using an artificial neural network. For this purpose, Fagus orientalis, Castanea sativa, Pinus ...sylvestris, and Picea orientalis wood samples at 8%, 12%, and 15% moisture content (MC) were machined on a CNC router in both across and along the grain directions. Based on the experimental data of surface roughness and cutting power analyses, a total of 16 models were used. These were selected in hundreds of models that have the lowest error. The spindle speed, feed rate, and the number of cutter teeth were chosen to be different with the literature based on the length of cutter mark. As a result, optimum machining parameters were determined for each wood MC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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