Enhancing the optical properties of transparent wood by plasma modification

Bioinspired thermochromic transparent hydrogel wood with advanced optical regulation abilities and mechanical properties for windows

Optical and mechanical properties of multilayered transparent wood

Fabrication of eco-friendly transparent wood for UV-shielding functionality

In this paper, poplar was used as raw material, sodium chlorite was used to delignify it in acidic environment, and then epoxy resin was vacuum impregnated in the delignified wood template to prepare transparent wood. Moreover, in order to imitate the lamination method of plywood, the multilayer transparent wood was prepared by means of staggered vertical lamination. The purpose of this paper is to study the physical and chemical properties of multilayer transparent wood, and to explore the application potential of multilayer transparent wood as a new material by comparing with single layer transparent wood with the same thickness. The weight of wood components in the transparent wood prepared in this experiment accounts for about 30–45% of the weight of composite materials. Scanning electron microscopy (SEM) measurements, Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR) characterization, weight gain measurements, UV transmittance measurements, color difference measurements, water contact angle measurements and mechanical properties measurements were used to study. The results showed that as the thickness of the transparent wood increased, the cracks between the resin and the wood cell wall increased, and the interface showed an uneven state. In the case of the same thickness, the multilayer transparent wood was made by laminating transparent wood sheets, with fewer internal cracks and smooth interfaces. Its light transmittance is better than single layer transparent wood. Moreover, compared with single layer transparent wood with the same thickness, the lightness of multilayer transparent wood decreased, and tended to yellow and red. Due to the removal of lignin, the tensile strength of transparent wood decreased during the preparation process. However, it can be seen from the mechanical strength test that the tensile strength of multilayer transparent wood is much higher than that of single layer transparent wood. To a certain extent, multilayer transparent wood can improve the mechanical strength of transparent wood. To conclude, multilayer transparent wood is a kind of natural transparent material with large thickness, good light transmission and excellent mechanical properties, and it has a good development prospect.

Impact of delignification on morphological, optical and mechanical properties of transparent wood

Transparent jute fiber (TJF) was prepared from delignified jute fiber (DJF) and was subjected to various surface knitting densities (190 and 340 g/m2) before epoxy resin (ER) impregnation under vacuum. The preparation process and properties of TJF were evaluated. The mechanical properties and surface morphology of the jute fiber samples were also studied. The mechanical properties were compared with transparent coir fiber (TCF) and transparent balsa wood (TBW). Optical properties, such as surface color, optical transmittance, and visual haze, of natural jute fiber (JF) and TJF were measured to better understand the influence of delignification. The experimental results showed transparency of 51% even for dense jute fiber cloth, and the maximum transmittance was as high as 60% with a low surface density. TJF had similar tensile strength as TBW but was higher than TCF, indicating a maximum tensile strength of 43.25 MPa with a surface density of 340 g/m2. These results suggest that TJF has the potential to meet the particular optical and mechanical properties of transparent wood. Transparent jute fiber can replace transparent wood for industrial production because of the simple preparation process and lower price.

Large size translucent wood fiber reinforced PMMA porous composites with excellent thermal, acoustic and energy absorption properties

Two common tree species of Betula alnoides (Betula) and New Zealand pine (Pinups radiata D. Don) were selected as the raw materials to prepare for the partially transparent wood (TW) in this study. Although the sample is transparent in a broad sense, it has color and pattern, so it is not absolutely colorless and transparent, and is therefore called partially transparent. For ease of interpretation, the following “partially transparent wood” is referred to as “transparent wood (TW)”. The wood template (FW) was prepared by removing part of the lignin with the acid delignification method, and then the transparent wood was obtained by impregnating the wood template with a refractive-index-matched resin. The goal of this study is to achieve transparency of the wood (the light transmittance of the prepared transparent wood should be improved as much as possible) by exploring the partial delignification process of different tree species on the basis of retaining the aesthetics, texture and mechanical strength of the original wood. Therefore, in the process of removing partial lignin by the acid delignification method, the orthogonal test method was used to explore the better process conditions for the preparation of transparent wood. The tests of color difference, light transmittance, porosity, microstructure, chemical groups, mechanical strength were carried out on the wood templates and transparent wood under different experimental conditions. In addition, through the three major elements (lignin, cellulose, hemicellulose) test and orthogonal range analysis method, the influence of each process factor on the lignin removal of each tree species was obtained. It was finally obtained that the two tree species acquired the highest light transmittance at the experimental level 9 (process parameters: NaClO2 concentration 1 wt%, 90 °C, 1.5 h); and the transparent wood retained most of the color and texture of the original wood under partial delignification up to 4.84–11.07%, while the mechanical strength with 57.76% improved and light transmittance with 14.14% higher than these properties of the original wood at most. In addition, the wood template and resin have a good synergy effect from multifaceted analysis, which showed that this kind of transparent wood has the potential to become the functional decorative material.

This study explores lignin-retaining transparent wood biocomposite production through a lignin-modification process coupled with epoxy resin. The wood's biopolymer structure, which includes cellulose, hemicellulose, and lignin, is reinforced with the resin through impregnation. This impregnation process involves filling the voids and pores within the wood structure with resin. Once the resin cures, it forms a strong bond with the wood fibers, effectively reinforcing the biopolymer matrix and enhancing the mechanical properties of the resulting biocomposite material. This synergy between the natural biopolymer structure of wood and the synthetic resin impregnation is crucial for achieving the desired optical transparency and mechanical performance in transparent wood. Investigating three distinct wood species allows a comprehensive understanding of the relationship between natural and transparent wood biocomposite properties. The findings unveil promising results, such as remarkable light transmittance (up to 95%) for Aspen transparent wood. Moreover, transparent wood sourced from White Spruce demonstrates excellent stiffness (E = 2450 MPa), surpassing the resin's Young's modulus. Also, the resin impregnation enhanced the thermal stability of natural wood. Conversely, transparent wood originating from Larch showcases superior impact resistance. These results reveal a clear correlation between wood characteristics such as density, anatomy, and mechanical properties, and the resulting properties of the transparent wood.

Biodegradable transparent wood was fabricated by introducing epoxy resin E51 modified with the silane coupling agent (KH550) into bleached poplar veneer. The light transmittance of transparent wood was modulated by KH550 content. The silane coupling agent KH550 was able to change the compatibility of epoxy resin and wood substrate, thereby affecting the performance of transparent wood. In this study, the effect of KH550 on the properties of transparent wood and its mechanism were investigated. The light transmittance, tensile strength, and elongation at break of transparent wood showed an increasing and then decreasing trend with increased KH550 dosage. When the mass ratio of the coupling agent KH550 to the epoxy resin was 1:20, the transparent wood made by impregnating wood substrate with epoxy resin modified by KH550 had the best performance, with the fast degradation starting temperature of 338 °C, 81.07% light transmittance at λ = 780 nm, 59.92 MPa tensile strength, and 3.47% elongation at break. This work provides a new way for preparing high performance transparent wood.

Preparation and properties of hydrophobic and transparent wood

Transparent wood (TW) was prepared by directly impregnating the wood cell wall and cavity with index-matched prepolymerized methyl methacrylate (MMA). In this process, lignin is retained compared with the preparation of transparent wood in the past, making the production faster and more energy-efficient. The innovation lies in that the prepared transparent wood retains the natural color and texture of the wood while transmitting light, especially under the illumination of a specific light source, which exist as the special visual effects. In order to enhance the practicality of the research and effectively expand the types of home decoration materials, six common wood species with different densities were selected in the experiment. Then the characteristics and mechanisms of wood, that is, color difference, light transmittance, microstructure, changes of chemical functional groups, and tensile strength, before and after PMMA impregnating were compared and analyzed. It is concluded that the light transmittance and mechanical properties of the wood have been improved, and a good synergistic effect between wood and PMMA has been confirmed by the analysis of scanning electron microscopy and infrared spectroscopy. The above highlights make pervious to transparent wood, which has the potential as an excellent functional decorative material.

In this study, we fabricated transparent wood that can replace transparent building materials, such as glass or plastic, and analyzed its electromagnetic properties through experiments. The results of the dielectric constant measurement experiment revealed that the electromagnetic properties of the fabricated transparent wood differ from those of conventional wood. The waveguide measurement method was used to investigate the electromagnetic wave transmission and reflection properties of the transparent wood. The results were compared with those of a simulation, and agreement between the results was confirmed. We found, by studying the electromagnetic shielding performance through an indium tin oxide coating, that the proposed transparent wood can be used as an eco‐friendly electromagnetic shielding material.

Transparent wood with self-cleaning properties for next-generation smart photovoltaic panels

The optical response of hierarchical materials is convoluted, which hinders their direct study and property control. Transparent wood (TW) is an emerging biocomposite in this category, which adds optical function to the structural properties of wood. Nano‐ and microscale inhomogeneities in composition, structure, and at interfaces strongly affect light transmission and haze. While interface manipulation can tailor TW properties, the realization of optically clear wood requires detailed understanding of light–TW interaction mechanisms. Herein is shown how material scattering and absorption coefficients can be extracted from a combination of experimental spectroscopic measurements and a photon diffusion model. Contributions from different length scales can thus be deciphered and quantified. It is shown that forward scattering dominates haze in TW, primarily caused by refractive index (RI) mismatch between the wood substrate and the polymer phase. Rayleigh scattering from the wood cell wall and absorption from residual lignin have minor effects on transmittance, but the former affects haze. Results provide guidance for material design of transparent hierarchical composites toward desired optical functionality; it is demonstrated experimentally how transmittance and haze of TW can be controlled over a broad range.