Effect of tannic/gallic acid-iron dyeing treatment on surface color and light fastness of bamboo veneer.

Currently, the quest for bamboo materials with high color fastness, rich colors and environmental friendliness is rapidly rising due to its potential applications in construction, furniture and decoration. However, finding an easy-to-operate and environmentally friendly dye for bamboo is a necessary task because of the difficulty in treating the dyeing waste liquid of acid dyes and the complexity of the production process of reactive dyes.Five formulations involving metal polyphenol complexes were employed to straightforwardly produce eco-friendly dyed bamboo and the impact of various formulations on the light aging resistance of the dyed veneers was examined. The results indicated that the light resistance of bamboo veneer dyed with the solution containing only FeSO4·7H2O and tannic acid reached level 4, surpassing the undyed bamboo veneer by three levels. The mechanism of enhanced lightfastness of dyed bamboo veneer was elucidated by XPS analysis. The polyphenol iron complex serves a dual purpose: it absorbs ultraviolet rays and scavenges free radicals within the system. Additionally, it reduced the oxidation of phenolics in the substrate, transforming them into dark-colored quinone structures. This process enhanced the light-aging resistance of the finishing materials. Therefore, this work provides a simple and environmentally friendly method for changing the color of bamboo and provides a new idea for the selection of dyes for bamboo dyeing in actual production.

Preparation and Characterization of Wood Scrimber Based on Eucalyptus Veneers Complexed with Ferrous Ions.

Wood-based products manufactured from fast-growing wood species such as eucalyptus have gained increasing attraction with the demand of using wood in architecture, furniture, and decoration. In this paper, a new type of wood scrimber based on eucalyptus veneers complexed with ferrous ions was prepared and its properties were characterized. The results showed that the presence of complexes did not affect the mechanical properties of eucalyptus wood scrimber, but made its surface more hydrophobic (contact angle increased by 38.48% and dimensional stability improved (thickness swelling rate decreased by 32.26%). Most importantly, the color of eucalyptus wood scrimber changed significantly, from the original brown to dark blue, and its anti-photoaging property also greatly improved. These advantages would make this type of wood scrimber based on the eucalyptus veneer complexes with ferrous ions more widely applicable in decorations and buildings.

Bamboo cellulose fibers prepared by different drying methods: Structure-property relationships.

Bamboo cellulose fibers (BCFs) has attracted increasing attention in many fields due to its high mechanical strength and interconnected porous structure. Drying is a key factor that determines the final structure and properties of BCFs. In this work, three kinds of BCFs, i.e., conventional-dried (CD-BCFs), freeze-dried (FD-BCFs), and supercritical CO2-dried (SD-BCFs), were prepared via different drying methods. The effects of drying methods on their supramolecular structure, porosity, and mechanical properties were studied, and the structure-property relationships were proposed. The CD-BCFs composed of well-aligned crystalline nanofibrils with a dense structure exhibited the best mechanical properties (tensile strength of 854.54 MPa). The SD-BCFs featured with interconnected 3D microfibril networks give a highly porous structure and the highest surface area of 9.162 m2/g. The FD-BCFs showed medium mechanical properties and surface area owing to the stacked lamellar microfibril network. This work provides guidelines for designing BCFs with proper structure for various end-use applications.

Durability Evaluation of Outdoor Scrimbers Fabricated from Superheated Steam-Treated Bamboo Fibrous Mats.

With natural texture and high performance, bamboo scrimber is one of the artificial lignocellulosic composites widely used in construction, furniture and other structural applications. However, it is vulnerable to the actions of water, ultraviolet radiation and fungus, which affect its durability, especially in the open. Here, bamboo was treated with superheated steam in an attempt to improve the durability of bamboo scrimbers. The chemical composition, mechanical properties, dimensional stability, aging resistance, decay resistance and anti-mildew properties were investigated at different temperatures (160~200 °C). After superheated steam treatment, the relative contents of holocellulose and α-cellulose in bamboo decreased. The bending strength and short-beam shearing strength slightly decreased as the temperature was raised while the modulus was essentially retained. The aging resistance in terms of thickness swelling rate (≤9.38%) was substantially improved. The decay resistance reached to the level of Grade I and can be dramatically enhanced by elevating temperature. The anti-mildew properties were also improved. To take together, superheated steam treatment remarkably improves the resistance of bamboo scrimbers to water, ultraviolet radiation, rot fungi and mildew with some concomitant reduction in mechanical properties. The results will permit outdoor construction using bamboo scrimbers more resistant to environmental damage.

Outdoor Wood Mats-Based Engineering Composite: Influence of Process Parameters on Decay Resistance against Wood-Degrading Fungi Trametes versicolor and Gloeophyllum trabeum.

The process parameters significantly influence the preparation and final properties of outdoor wood mats-based engineering composite (OWMEC). During outdoor use, wood composites are susceptible to destruction by rot fungi. Herein, the role of process parameters such as density and resin content on OWMEC resistance to fungal decay was investigated. The poplar OWMEC samples were exposed to white-rot fungus Trametes versicolor and brown-rot fungus Gloeophyllum trabeum for a period of 12 weeks. The chemical composition, crystallinity, and morphology were evaluated to investigate the effect of process parameters on the chemical composition and microstructure of the decayed OWMEC. With an increase in the density and resin content, the mass loss of the decayed OWMEC decreased. The highest antifungal effect against T. versicolor (12.34% mass loss) and G. trabeum (19.43% mass loss) were observed at a density of 1.15 g/m3 and resin content of 13%. As results of the chemical composition and microstructure measurements, the resistance of OWMEC against T. versicolor and G. trabeum fungi was improved remarkably by increasing the density and resin content. The results of this study will provide a technical basis to improve the decay resistance of OWMEC in outdoor environments.