In this study, mechanical fluffing, thermal treatment, and phenol formaldehyde (PF) impregnation, as well as cold-in and cold-out hot-pressing processes, were used to fabricate bamboo scrimbers. The water absorption, dimensional stability, and mechanical properties of the bamboo scrimbers were determined. The bamboo scrimber made from bamboo bundles processed at 180 °C hot dry air treatment combined with 18 % PF resin loading showed good technological properties. This bamboo scrimber had improved water absorption, as well as thickness and width swelling behavior, which is favorable for application to outdoor landscaping, exterior decoration, and garden furniture. The bamboo scrimber made from bamboo bundles processed at 0.35 MPa saturated steam treatment showed excellent mechanical strength, which is favorable for structural application.

Fabrication, material properties, and application of bamboo scrimber

The objective of this study was to evaluate the uniformity of density distribution for Bamboo-bundle Laminated Veneer Lumber (BLVL) and its relationship to the stability of mechanical performance. A novel assembly style called one-piece veneer formation technology was developed to enhance the density uniformity, and four different density levels for BLVL were examined by X-ray scanning. The results indicated that the homogeneity of density, the stability of mechanical performance, and the mechanical properties for BLVL could be effectively improved by assembling the bamboo bundles into layers and then combining the layers to make the lumber. The density uniformity in width and thickness directions increased with increasing target density. A negatively linear correlation between density and Coefficient of Variation (COV) of MOR and shearing strength was observed. Partial correlation analysis revealed that when controlling for the variability of density, the linear relationship between density and the COV of MOR became insignificant, and the degree of linear correlation between density and the COV of shearing strength decreased.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_09_1_554_Chen_Evaluation_Uniformity_Density_Bamboo/2493

Evaluation of the Uniformity of Density and Mechanical Properties of Bamboo-Bundle Laminated Veneer Lumber (BLVL)

At present, China is the world's largest producer of bamboo resource possessor and bamboo processing. The main processing method of bamboo recombination technology is rolling and compaction, by which a reconstituted material with bamboo fibrotic veneer as matrix and phenolic resin as reinforcement is prepared. It has excellent physical and mechanical properties and can replace high-quality wood to manufacture various engineering structural materials and building decoration materials. This paper reviewed the research process and progress of bamboo recombination technology, the existing technical problems and prospects, in order to provide references for future research on bamboo recombination theory and production practice. In recent years, as a new material with controllable properties, designable structures, and adjustable dimensions, bamboo reconstituted materials have been comprehensively studied from the aspects of pressing process parameters, physicochemical mechanical properties evaluation system, and microstructure characterization, but the research is not comprehensive and has not in-depth view. In the future, the relationship between microstructure and performance should be emphatically studied to clarify the law of mechanical performance change and ultimate mechanical performance under synergistic enhancement effect, as well as the performance change and interface formation of the resin during the entire molding process. Meanwhile, the reliability and relevance of applied research should be further expanded, and the integration of natural and artificial aging environment, process and performance, and macro- and microscales should be strengthened.

/pdf/progress-of-bamboo-recombination-technology-in-china-h8m8i5yuz6.pdf

Progress of Bamboo Recombination Technology in China

Fibrous veneers in loose structure were made from Neosinocalamus affinis bamboo, and then used as the basic element for bamboo-based fiber composites. Steam treatment of the fibrous veneers was performed inside an autoclave at 0.35 MPa to 0.45 MPa (147°C to 155°C) for 110 min to 170 min. After steam treatment, all three color parameters (L*a*b*) of fibrous veneers were changed significantly. The color change (ΔE*) increased with higher pressure and longer duration. The chemical properties of steam-treated samples were examined using chemical analysis. A decrease in the content of holocellulose and α-cellulose with an elevation in steam treatment was found. The water extractives content and buffering capacity increased, and the effect of pressure and duration on them increased significantly. pH value decreased significantly compared with control samples, but only small variations were found among steam-treated samples. Through correlation analysis, pH value was strongly correlated to hemicellulose...

Effect of Steam Heating on the Color and Chemical Properties of Neosinocalamus Affinis Bamboo

The objective of this study was to investigate the deformation behavior of bamboo bundle laminated veneer lumber (BLVL) manufactured with veneer preprocessing densification technology under low velocity impact loading. The influence of different preprocessing temperatures, times, and stacking sequences was studied with respect to impact loading. Laminates with bamboo bundles parallel to the length direction were labeled as type I, and cross-ply was labeled as type II. The results indicated that delamination and fiber breakage were the main damage models for BLVL made with veneer preprocessing densification technology, and its impact performance under a veneer prepressing temperature of 90 °C and a time of 10 min was fairly comparable to that of BLVL without preprocessing densification. The impact index decreased as the densification temperature increased. The impact properties for type II were better than that of type I. The curve characteristic of impact deflection vs. time presented a linear trend, while the curve of impact velocity first decreased and then tended to level off as time elapsed.

/pdf/impact-properties-of-bamboo-bundle-laminated-veneer-lumber-1a5qr9783j.pdf

Impact properties of bamboo bundle laminated veneer lumber by preprocessing densification technology

The authors developed a new technology for making laminated fibrillated-veneer lumber.They designed an experiment using bamboo(Bambusa distegia) to optimize the processing parameters.The effect of resin impregnation rate on mechanical performance and water resistance was discussed.The results showed that increasing specimen resin content from 7% to 13%,had a negative impact on the average modulus of rupture(MOR) and tensile strength,and a positive influence on the shear strength and water resistance.However,the increase in resin content didn't affect the modulus of elasticity(MOE) or compression strength.The authors suggested that the panel's mechanical performance and water resistance could be predicted by controlling the resin impregnation level to meet different application demands.

YU Wen-ji

Papers

Effect of Resin Impregnation Rate on Physical and Mechanical Properties of Laminated Bamboo Fibrillated-Veneer Lumber