Bamboo Timber Research Articles

Bamboo particle reinforced polypropylene composites made from different fractions of bamboo culm: Fiber characterization and analysis of composite properties

AbstractDifferences in anatomical structure and chemical composition of bamboo fractions have an obvious influence on the properties of bamboo thermoplastic composites (BPCs). Six fractions of bamboo particles including bamboo culm (BC), bamboo green (BG), bamboo timber (BT), bamboo yellow (BY), bamboo node (BN), and bamboo processing residue (BR) were prepared and compounded with polypropylene (PP) to fabricate BPCs using extrusion. The anatomical structure, chemical composition, crystallinity, and morphology of the bamboo particles were characterized. The processability, mechanical properties, creep‐recovery, and dynamic viscoelasticity of the BPCs were evaluated. The results show that the anatomical structure and composition of the bamboo fractions influenced the crystallinity, morphology, and aspect ratio (L/D) of the bamboo particles, as well as the performance of the resulting composites. BG had the largest crystallinity, length, and L/D, followed by BC and BT. BY was the shortest with the smallest L/D. The BC/PP composites exhibited the best processability and optimal mechanical properties. The BG/PP composites had the highest modulus and creep resistance. The BY/PP composites had the poorest processability and mechanical performance. These results indicate that BG from processing residues can be recycled into high‐value composites and provide a scientific basis for further research on BPCs made from bamboo processing residues.

Fabrication of Hydrophobic ZnO/PMHS Coatings on Bamboo Surfaces: The Synergistic Effect of ZnO and PMHS on Anti-Mildew Properties

Poor mildew resistance has limited the application of bamboo materials. In this work, ZnO/PMHS coatings were fabricated on bamboo timber surfaces by hydrothermal synthesis method and hydrophobic modification with poly(methylhydrogen)siloxane (PMHS). The surface chemical characteristics and microstructure of the bamboo before and after modification were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and water contact angle (WCA). The morphology results indicated that ZnO on the surface of bamboo forms flower-like aggregations. The WCA of ZnO/bamboo increased from 65° to 142° after PMHS hydrophobic modification, indicating that the hydrophobicity of bamboo was significantly improved. The original bamboo had poor anti-mildew properties when exposed to Trichoderma viride, Aspergillus niger, and Penicillium citrinum. After depositing ZnO onto the surface of the bamboo, the anti-mildew properties were significantly improved. Furthermore, it was found that after PMHS hydrophobic modification, ZnO/bamboo had excellent anti-mildew properties when exposed to the three mold hyphae, which indicated that PMHS hydrophobic modification had a synergistic effect on the anti-mildew properties of bamboo with a ZnO coating.

Improved mould resistance and antibacterial activity of bamboo coated with ZnO/graphene.

Bamboo is susceptible to mould and attack by fungi because of its high content of starch and sugar. To make bamboo-based outdoor materials, a new type of bamboo timber with improved mould resistance and antibacterial activity, coated with reduced graphene oxide and nanocrystal ZnO (abbreviated as RGO@ZnOBT), was fabricated by a two-step dip-dry and hydrothermal process. A possible synthesis mechanism for RGO@ZnOBT was investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscope, energy-dispersal X-ray analysis, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. According to the China standard test method, the Aspergillus niger mould resistance of RGO@ZnOBT is grade 2, whereas the Trichoderma viride and Penicillium citrinum mould resistance of RGO@ZnOBT is grade 0, both of which are better than the grade 4 of original bamboo timber. The Escherichia coli resistance test showed that the antibacterial circle of RGO@ZnOBT is 3 mm, which is significantly higher than that of original bamboo timber (0 mm). The antibacterial activity of treated bamboo is significantly improved compared with that of untreated bamboo.

Bamboo Conditions for Processing Bamboo Fiber with Combing Method

The bamboo fibre is a new kind of natural fibre from bamboo with machine method, and is in the frontier of bamboo timber processing, new composite and textile research field. The combing method is mainly one in processing bamboo fiber. The plasticity and strength of bamboo were required in processing bamboo fiber by machine method. The aim of this work is to explore changes of mechanical properties -lengthways tensile properties of bamboo after alkali treatment and focuses on a relation between lengthways tensile properties of alkali treated bamboo and the moisture content. Mechanism of plastic deformation of bamboo was initially revealed in this paper. Experiment shows that: above fibre saturation point, the lengthways tensile strength and elasticity modulus of bamboo decreased with increase of moisture content with 2.5%NaOH soaking for 24h, and bamboo plasticity is better when its moisture content is between 40% and 90%. According to the principle of bamboo fiber processing by combing, the moisture content of bamboo should be controlled from 50% to 70% after 24h soaked with 2.5%NaOH. Bamboo fiber processing test shows that the conclusion is correct.

Comparative characterization of ethanol organosolv lignin polymer from bamboo green, timber and yellow

In order to make better use of bamboo resources in industrial processes, it is necessary to understand its recalcitrant morphological stem structure and unique chemical composition. In the present work, microspectroscopic imaging approaches were used to reveal the heterogeneous distribution of lignin at cellular and subcellular level. Results showed the higher lignin concentration in the narrow layer of fiber and parenchyma secondary cell walls. Furthermore, ethanol organosolv lignin, isolated from different zones of the bamboo vascular tissue [outer (green), middle (timber) and inner (yellow)], was subjected to extensive structural characterization, including chemical component analysis, Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric/differential thermal analysis (TGA/DTA), and nuclear magnetic resonance (NMR). Main chemical differences among the green, timber and yellow zone were sugar content and S/G/H ratios. Since bamboo green had higher density, hardness and lignin content than bamboo timber and bamboo yellow, the mass transfer during the organosolv process was limited and resulted in the reduced removal/dissolution of polysaccharides at the same acidic conditions. Because bamboo green exhibited the highest content of G units in the vascular tissue, it was more condensed and thus had increased thermal stability compared to bamboo timber and bamboo yellow.

Fabrication of Hydrophobic Indonesia Bamboo Modified by Octa Fluoro 1-Pentanol (OFP) Based on TiO2 Thin Film for Self-cleaning Application

The ultra-hydrophobic surface on Indonesia bamboo timber has been successfully prepared using OFP (2,2,3,3,4,4,5,5-octafluoro-1-pentanol) as a modifier agent. The hydrothermal method has been used to fabricate anatase TiO 2 film followed by OFP modification. Maximal water contact angle of 123 ο has been obtained for the composition of 10 mL of OFP and 15 mL of 2-propanol (B-T-OFP10). XRD analysis showed the existence of pure anatase TiO 2 film on bamboo timber, confirmed by EDS result. SEM image of a TiO 2 -coated and a typical ultra-hydrophobic bamboo timber revealed irregular aggregates of spherical TiO 2 on the surface and compact ultra-hydrophobic surface, respectively. The optimum sample (B-T-OFP10) showed excellent mechanical stability, self-cleaning property, and flame retardancy compared to pure bamboo timber.

Comparison of three processing methods for laminated bamboo timber production

Three processing techniques, split-squaring (SS), V-grooving (VG), and split-edging (SE), were evaluated and compared in terms of their processing time and recovery. Semantan bamboo (Gigantochloa scortechinii Gamble) was used as a raw material and the results showed that the VG-method required the longest processing time (32.1 min), followed by the SS-method (18.2 min), and the SE-method (17.9 min). However, the VG-method showed the highest recovery (82.0%) compared to the SS-method and SE-method, 31.0 and 49.4%, respectively. When both processing time and recovery factors were combined with the same weighing factor, the highest value was recorded with the VG-method (49.1), while the SE-method had values of 31.1 and the SS-method 12.8. The results suggest that the VG-method is the best option. However, the V-grooving machine is still a prototype and therefore the SE-method could be an alternative option until the improved V-grooving machine is available.

Layer-by-layer self-assembly of reduced graphene oxide on bamboo timber surface with improved decay resistance

Because bamboo is easily attacked by many fungi, and conventional preservatives have many disadvantages including environmental pollution and human health damage, bamboo products should be protected with environmentally friendly methods. Herein, a novel and efficient process for fabrication of antifungal bamboo timber by coating with graphene materials is presented. The crystal phase, morphology, microstructure and other physicochemical properties of the as-prepared samples were characterized by XRD, Raman, SEM, EDX, XPS and FTIR. XRD studies and Raman spectrum confirmed that graphene oxide was reduced to graphene aggregates in the one-step hydrothermal reduction process. SEM images proved that reduced graphene oxide (RGO) nanoplates were deposited on bamboo timber surface by layer-by-layer self-assembly. EDX proved the carbon element composition of RGO coating on the bamboo surface. XPS and FTIR indicated strong interaction of hydrogen bond between bamboo substrate and RGO coating. The anti-fungal activity of bamboo timber with RGO coating was improved significantly when bamboo was infected by Gloeophyllum trabeum and Panerochaete chrysosporium.

Experiment on Behavior of a New Connector Used in Bamboo (Timber) Frame Structure under Cyclic Loading

Connection is an important part of the bamboo and timber structure, and it directly influences the overall structural performance and safety. Based on a comprehensive analysis of the mechanical performance of several wood connections, a new connector for the bamboo (timber) frame joint was proposed in this paper. Three full‐scale T‐type joint specimens were designed to study the mechanical performance under cyclic loading. The thickness of the hollow steel column was different among three specimens. The specimens were loaded under displacement control with a rate of 10 mm per minute until the specimens reach failure. It was observed that the failures of three specimens were caused by the buckling of flanges in the compression and that the steel of connections does not yield. The load‐displacement hysteretic curve for three specimens is relatively plump, and the stiffness of connection degenerates with the increasing of cyclic load. The maximum rotation is 0.049 rad, and the energy dissipation coefficient is 1.77. The thickness of the hollow steel column of the connector has significant impact on the energy dissipation capacity and the strength of the connection. A simplified moment‐rotation hysteresis model for the joint was proposed.

Durable, high conductivity, superhydrophobicity bamboo timber surface for nanoimprint stamps

Superhydrophobic bamboo timber was fabricated by magnetron sputtering and nanoimprint stamps. Conductive copper film was deposited on the surface of bamboo timber, followed by transferring lotus leaf structure pattern to the Cu-bamboo timber surface. Modified by stearic acid, the as-prepared surface with lotus leaf structure showed superhydrophobic property with the water contact angle of 152°, and the sliding angle was only 5°. The coating showed excellent mechanical resistance, environmental stability and high conductivity. It was expected that this work could promote the applications of superhydrophobic and conductive bamboo products.

Fabrication of nanocrystalline anatase TiO2 in a graphene network as a bamboo coating material with enhanced photocatalytic activity and fire resistance

Many bamboo products are used in the textile industry and are exposed to dyeing wastewater. To improve its photocatalytic activity, nanocrystalline anatase TiO2 in a graphene network on a bamboo substrate was synthesized by two hydrothermal processes. The crystal phase, morphology, microstructure and other physicochemical properties of the original bamboo timber (BT), BT coated with reduced graphene oxide (RGOBT), BT coated with TiO2 (TiO2BT) and RGOBT coated with TiO2 (RGO@TiO2BT) were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis. BT, RGOBT and RGO@TiO2BT were analyzed by Fourier transform infrared spectroscopy. The RGO@TiO2BT composite possesses excellent photocatalytic activity which are superior to those of BT, RGOBT and TiO2BT. The photodegradation efficiency of methyl orange, methylene blue and rhodamine B are 87.2%, 85.1% and 73.9% after 60 min UV photodegradation respectively, which are superior to those of BT, RGOBT and TiO2BT. Additionally, RGO@TiO2BT exhibited improved thermal stability and fire-resistant properties with a limiting oxygen index of 33.2%.

Preliminary studies of multi-micro/nanomaterials immobilized on the bamboo timber surface

Bamboo, a kind of forest resources only less important than wood, is especially easy to be degraded during exposure to outdoor environments. Nowadays, researchers endeavor to synthesize the multi-micro/nanomaterials on the bamboo timber surface to improve its intrinsic properties and impart excellent performances to bamboo products. In this study, multi-micro/nanomaterials including ZnO, TiO2, CaCO3, MnO2, SiO2, Ag, λ-Fe2O3, and graphite/ZnO, have been successfully immobilized on the bamboo timber surface using different methods including hydrothermal method, silver mirror reaction, and co-precipitation process. The geometric microstructures and crystalline structures of the materials on the bamboo timber surface were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. SEM observations showed that the surface of the bamboo timber was densely covered with the uniform micro/nanomaterials, which surrounded the entire surface of the bamboo timber. XRD patterns confirmed that only high purity micro/nanomaterials were formed on the surface of bamboo timber. The mechanical stability of the coating on the bamboo timber surface was also characterized by a 3M tape test. In the process of manufacturing of these micro/nanomaterials, it is exceedingly important to offer a potential opportunity to accelerate the large-scale production of woody functional materials for new industrial applications.

Room temperature synthesis of crystalline anatase TiO2 on bamboo timber surface and their short-term antifungal capability under natural weather conditions

A facile room temperature route was developed for growing crystalline anatase TiO2 on the bamboo timber surface by a unique hydrolysis of titanium complexes in the presence of H3BO3. The effect of aging time on TiO2 crystallinity on the bamboo timber surface was studied. The crystal phase, microstructure, and chemical composition of the anatase TiO2 formed on the bamboo timber surfaces were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). XRD characterization on the samples showed that, for crystallization occurred at room temperature, the longer the aging time, the greater the crystallinity. The TiO2-coated bamboo samples look identical to the pristine samples as there is no essential effect on the optical properties of the bamboo timber surface. Moreover, the antifungal activity of TiO2 photo-catalytic reaction against mould fungi was investigated for bamboo timber under natural weather conditions during periods of 16 weeks. Results show that compared with the pristine bamboo timber, the anatase TiO2-coated bamboo timber presented more superior antifungal capability under natural weather conditions in Hangzhou, China.

Durable, self-cleaning and superhydrophobic bamboo timber surfaces based on TiO2 films combined with fluoroalkylsilane

Decorative materials, including bamboo timber, have been proposed to exploit their superhydrophobic and self-cleaning properties, but a comprehensive appraisal of their environmental adaptability is still deficient. In this paper, a robust and durable superhydrophobic surface was formed on bamboo timber substrate through a process combining chemical solution deposition and chemical modification. The superhydrophobic surface resulted from micro-nanoscale binary-structured TiO2 films and the assembly of low-surface-energy fluorinated components, which exhibited a water contact angle of 163±1° and a sliding angle of 3±1°. The surface maintained superhydrophobicity after mechanical abrasion against 1500 mesh SiC sandpaper for 800mm at the applied pressure of 1.2kPa, indicating good mechanical stability. Moreover, the superhydrophobic surface exhibited good chemical stability against both acidic and basic aqueous solutions (e.g., simulated acid rain). After exposure to atmosphere for more than 180 days, the obtained surface still maintained a contact angle of 155±2° and a sliding angle of 6±2°, revealing good long-term stability. In addition, the as-prepared superhydrophobic surface exhibited almost complete wet self-cleaning of dirt particles with water droplets. It is believed that the method presented in this study can provide a straightforward and effective route to fabricate a large-area, mechanically robust, anticorrosive and self-cleaning superhydrophobic surface on woody materials for a great number of potential applications.

Rapid determination of chemical composition and classification of bamboo fractions using visible-near infrared spectroscopy coupled with multivariate data analysis.

BackgroundDuring conversion of bamboo into biofuels and chemicals, it is necessary to efficiently predict the chemical composition and digestibility of biomass. However, traditional methods for determination of lignocellulosic biomass composition are expensive and time consuming. In this work, a novel and fast method for quantitative and qualitative analysis of chemical composition and enzymatic digestibilities of juvenile bamboo and mature bamboo fractions (bamboo green, bamboo timber, bamboo yellow, bamboo node, and bamboo branch) using visible–near infrared spectra was evaluated.ResultsThe developed partial least squares models yielded coefficients of determination in calibration of 0.88, 0.94, and 0.96, for cellulose, xylan, and lignin of bamboo fractions in raw spectra, respectively. After visible–near infrared spectra being pretreated, the corresponding coefficients of determination in calibration yielded by the developed partial least squares models are 0.994, 0.990, and 0.996, respectively. The score plots of principal component analysis of mature bamboo, juvenile bamboo, and different fractions of mature bamboo were obviously distinguished in raw spectra. Based on partial least squares discriminant analysis, the classification accuracies of mature bamboo, juvenile bamboo, and different fractions of bamboo (bamboo green, bamboo timber, bamboo yellow, and bamboo branch) all reached 100 %. In addition, high accuracies of evaluation of the enzymatic digestibilities of bamboo fractions after pretreatment with aqueous ammonia were also observed.ConclusionsThe results showed the potential of visible–near infrared spectroscopy in combination with multivariate analysis in efficiently analyzing the chemical composition and hydrolysabilities of lignocellulosic biomass, such as bamboo fractions.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0443-z) contains supplementary material, which is available to authorized users.

Wet chemical synthesis of ZnO nanocoating on the surface of bamboo timber with improved mould-resistance

With the increasing emphasis on sustainable development, bamboo is receiving an increasing attention as a kind of forest resource. But bamboo is readily discoloured by mould fungi, which greatly limits the applications of bamboo. In this research, ZnO nanoparticles were successfully fabricated on the surface of bamboo timber by a simple low-temperature wet chemical method. The morphology, chemical structure, and crystalline structure of the samples were characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). XRD studies confirmed that the as-prepared ZnO nanoparticles were wurtzite. The microstructure and hydroxyl groups in the bamboo timber surface at the wet state provided cavities and affinity for the creation and the immobilization of ZnO nanoparticles on the bamboo timber surface through electrostatic and hydrogen bonding interactions. Moreover, the mould-resistance of ZnO coated bamboo timber was also in focus on the present study. The results indicated that bamboo timber treated with ZnO had a better resistance against Aspergillus niger V. Tiegh (A. niger) and Penicillium citrinum Thom (P. citrinum), but poor against Trichoderma viride Pers. ex Fr (T. viride).

The effects of nodes and resin on the mechanical properties of laminated bamboo timber produced from Gigantochloa scortechinii

The objective of this work was to evaluate the mechanical properties of laminated bamboo timber (LBT) manufactured from bamboo (Gigantochloa scortechinii). Bamboo strips containing nodes were used to produce laminated samples. Each bamboo mat was arranged with 5cm intervals ranging from 0cm to 15cm between the nodes in successive laminae. Phenol formaldehyde (PF) and polyvinyl acetate (PVAc) were used at two spread rates of 200g/m2 and 250g/m2. The best mechanical properties were found in samples without nodes. Increasing intervals also resulted in increasing strengths. In all the mechanical properties studied, PF had higher strength with 200g/m2 spread rate except for shear where PVAc had similar values with PF. It appears that interval levels in the joints influenced the overall mechanical properties of the samples.

Benefits from additives and xylanase during enzymatic hydrolysis of bamboo shoot and mature bamboo

Effects of additives (BSA, PEG 6000, and Tween 80) on enzymatic hydrolysis of bamboo shoot and mature bamboo fractions (bamboo green, bamboo timber, bamboo yellow, bamboo node, and bamboo branches) by cellulases and/or xylanase were evaluated. The addition of additives was comparable to the increase of cellulase loadings in the conversion of cellulose and xylan in bamboo fractions. Supplementation of xylanase (1mg/g DM) with cellulases (10FPU/g DM) in the hydrolysis of bamboo fractions was more efficient than addition of additives in the production of glucose and xylose. Moreover, addition of additives could further increase the glucose release from different bamboo fractions by cellulases and xylanase. Bamboo green exhibited the lowest hydrolyzability. Almost all of the polysaccharides in pretreated bamboo shoot fractions were hydrolyzed by cellulases with the addition of additives or xylanase. Additives and xylanase showed great potential for reducing cellulase requirement in the hydrolysis of bamboo.

Silver mirror reaction as an approach to construct a durable, robust superhydrophobic surface of bamboo timber with high conductivity

Silver nanoparticles (Ag NPs) were successfully in situ deposited onto the surface of the bamboo timber through a simple silver mirror reaction. Scanning electron microscopy (SEM) images showed that the surface of the bamboo timber was densely covered with the uniform Ag NPs, which made the intrinsic insulating bamboo timber conductive. With further modification by fluoroalkylsilane (FAS), the Ag NPs-covered bamboo timber showed superhydrophobicity with the water contact angle (WCA) of 155°. Simultaneously, the modified bamboo timber displayed a durable and robust superhydrophobic property even under corrosive solutions including acidic, alkali and NaCl solutions with different molar concentrations. Especially in harsh conditions of boiling water or intense water stirring, the modified bamboo timber remained superhydrophobicity and high conductivity.

Fabrication of superhydrophobic bamboo timber based on an anatase TiO2 film for acid rain protection and flame retardancy

A facile method for fabricating superhydrophobic bamboo timber based on an anatase TiO2 film for acid rain protection and flame retardancy is described in the present work.