Bamboo Blocks Research Articles

Bamboo as a natural optimized fiber reinforced composite: interfacial mechanical properties and failure mechanisms

Bamboo is a typical natural fiber-reinforced composite with an optimized distribution of vascular bundles as reinforcement and parenchyma tissues as bio-matrix. The interfacial bonding performance between vascular bundles and parenchyma tissue is critical for the mechanical properties and failure mechanisms of bamboo. This study employed pull-out tests to determine the interfacial shear strength (IFSS) between bamboo vascular bundles and parenchyma tissue and evaluate the critical embedded lengths () of vascular bundles. The effects of embedded vascular bundle lengths on interfacial strength and failure behaviors were also investigated. The results revealed a value of 2.51 mm, lower than the majority of plant fiber-reinforced composite materials, with an IFSS of around 20 MPa, surpassing most artificial bamboo fiber composites. The pull-out process of the vascular bundles involved elasticity, debonding, and sliding friction stage, where debonding energy absorption (DEA) outweighed frictional energy absorption (FEA) and increasing with embedded length. The primary failure features include interfacial debonding, parenchyma tissue ripping, delamination of fiber thin layers, and fiber breakage. Moreover, the parenchyma cells between the two fiber sheaths and at the top of the bamboo block readily detached. The interfacial failure mechanisms of bamboo included debonding, reinforcement, and matrix failure, with the proportions varying as the embedded length increased. Quantitative analysis of the interfaces structure and mechanical properties between vascular bundles and parenchyma tissues could provide a reference for the biomimicry of bamboo structures and the manufacturing of natural fiber-reinforced composite materials.

Swelling Behaviour of Bamboo (Phyllostachys pubescens)

Bamboo is a plant with various applications. As a natural, renewable material that exhibits good mechanical performance, it seems to be an interesting alternative to wood, which has become a scarce and expensive commodity. However, comprehensive knowledge of its properties is necessary to maximise its potential for various industrial purposes. The swelling behaviour of bamboo is one of the features that has not yet been sufficiently investigated. Therefore, in this research, we aimed to measure and analyse the swelling pressure and kinetics of bamboo blocks. The results show that similar to wood, the swelling kinetics of bamboo depend on its density: the denser the tissue, the higher the maximum swelling value recorded. The maximum tangential swelling measured was about 5%–6%, which is lower than the value for the most commonly used wood species. Swelling pressure ranged from 1.16 MPa to 1.39 MPa, depending on the bamboo density: the denser the sample, the shorter the time required to reach maximum swelling pressure. Like in wood, the smallest linear increase in size due to swelling was observed in the longitudinal direction (0.71%). However, opposite to wood, more pronounced swelling was recorded in the radial direction (over 7%) than in the tangential direction (nearly 6%). The results show that bamboo’s swelling behaviour makes it a good material for use in variable humidity conditions, being more favourable than the unmodified wood of many species.

Pull-out strength of the glued-in joint in laminated bamboo structure

The glued-in joint has proven its reliability, practicality, and flexibility in timber and concrete structures since first proposed. To study the pull-out strength of the glued-in joint in laminated bamboo structure, 27 specimens in pull-pull configuration were conducted. The influence of parameters, i.e., edge distance of the rebar, glue thickness, rebar diameter, anchorage length, were all tested by monotonic pull-out tests parallel to the grain. Three failure modes were characterized by the experimental results, referring to the splitting of laminated bamboo block, pull-out, and failure of rebar after yielding. Concluded from the experimental results, it is found that the first failure mode could be avoided by restricting the edge distance of the rebar in a reasonable range. The initial stiffness and load-carrying capacity of the latter two failure modes were recognized to be estimated in terms of the rebar diameter and anchorage length. Based on the existed theory, the feasibility of the traditional method was discussed and a simplified formula was developed based on the experimental results and theoretical derivation, which showed that the deviation is less than 6%. Finally, recommendations were made for the design of glued-in joint in the laminated bamboo structure.

Effect of bamboo pith ring on the stability of the gluing interface

As a natural bamboo structure, bamboo pith ring (BPR) is commonly discarded from bamboo composites because it influences the gluing process and might cause complex handling. This study founds that the cells in BPR and bamboo middle (BM) are vertically staggered, forming vertical interlacing layers at the bonding interface in Arc-shaped Bamboo Natural Laminated Lumber (ABNLL). The role of BPR in the bonding interface was analyzed from macroscopic to cell wall scale. The retention of BPR can reduce the longitudinal, radial, and tangential deformation of bamboo blocks and composites during shrinkage and swelling. This phenomenon may be since the deformation direction of the cells in BPR and BM is vertical in the process of water absorption and dehydration, and the existence of BPR inhibits the deformation of BM. The deformation of cells in different directions in BPR and BM results from microfibrils' arrangement and chemical properties. The arrangement direction of microfibrils in BPR and BM is perpendicular to each other, leading to the vertical deformation of cell deformation in water absorption and water loss. BPR has low crystallinity (24.01%), a large microfibril angle (16.22°), high hemicellulose content, and is more sensitive to water, so BPR has a faster deformation rate and larger deformation range than BM. BPR has little effect on the mechanical properties of bamboo composites. In addition, retaining BPR increased the mass and thickness of bamboo by 7.43% and 9.40%, respectively.

Competition patterns and biodegradation results of multiple fungal species on Moso bamboo (Phyllostachys edulis)

ABSTRACT The biodegradation of lignocellulosic materials in nature is a complex process. To investigate the fungal competition patterns and degradation on Moso bamboo (Phyllostachys edulis), four wood decay fungi, including white-rot and brown-rot fungi, were selected as the test fungi in this research. Bamboo blocks were pre-colonized by different fungi then paired to form dual cultures. The results showed different competition outcomes among these fungi on potato dextrose agar, forest soil, and bamboo. Whit-rot fungus Trametes versicolor was highly competitive on bamboo where it could replace brown-rot fungi, and the biodegradation of bamboo was more severe in dual cultures, especially in the combination of Trametes versicolor and Gloeophyllum trabeum. The degradation of the bamboo components also differed with the monocultures and dual cultures. In monocultures of brown-rot fungi, cellulose was the most severely degraded component among the three primary components; while in monocultures of white-rot fungi, lignin was the most severely degraded component instead. The degradation of hemicellulose and lignin was more significant than that of cellulose in the dual cultures containing white-rot fungi. These results suggest that dual culturing of decay fungi has the potential to improve biomass utilization of bamboo and reduce the chemical treatment cost of raw materials.

Agroforestry Suitability for Planning Site-Specific Interventions Using Machine Learning Approaches

Agroforestry in the form of intercropping, boundary plantation, and home garden are parts of traditional land management systems in India. Systematic implementation of agroforestry may help achieve various ecosystem benefits, such as reducing soil erosion, maintaining biodiversity and microclimates, mitigating climate change, and providing food fodder and livelihood. The current study collected ground data for agroforestry patches in the Belpada block, Bolangir district, Odisha state, India. The agroforestry site-suitability analysis employed 15 variables on climate, soil, topography, and proximity, wherein the land use land cover (LULC) map was referred to prescribe the appropriate interventions. The random forest (RF) machine learning model was applied to estimate the relative weight of the determinant variables. The results indicated high accuracy (average suitability >0.87 as indicated by the validation data) and highlighted the dominant influence of the socioeconomic variables compared to soil and climate variables. The results show that >90% of the agricultural land in the study area is suitable for various agroforestry interventions, such as bund plantation and intercropping, based on the cropping intensity. The settlement and wastelands were found to be ideal for home gardens and bamboo block plantations, respectively. The spatially explicit data on agroforestry suitability may provide a baseline map and help the managers and planners. Moreover, the adopted approach can be hosted in cloud-based platforms and applied in the different agro-ecological zones of India, employing the local ground data on various agroforestry interventions. The regional and national scale agroforestry suitability and appropriate interventions map would help the agriculture managers to implement and develop policies.

Observing bamboo dimensional change caused by humidity

Bamboo is a kind of natural biomaterials sensitive to moisture. The change of moisture content in bamboo leads to the cracking and deformation of bamboo. To understand the mechanism of swelling due to moisture change, the swellings were measured on bamboo blocks as well as separated fiber and parenchyma tissue under different humidity conditions in situ by using a dynamic vapor sorption (DVS) instrument and a charge-coupled device (CCD) camera. The results showed that when the relative humidity (RH) was above 40%, the main types of moisture in the bamboo blocks changed, and the area swelling of the bamboo blocks increased rapidly. When equilibrium moisture content (EMC) was 11.91%, the area swellings of the fibers (BF) and the vascular bundles (BV) in the bamboo blocks, and the bamboo blocks were 42.00%, 25.69%, and 4.26%, respectively. The content of the bamboo fiber plays a decisive role in bamboo swelling. For the separated fibers and parenchymal cells, when RH changed from 0% to 90%, the transverse swellings of the fibers and parenchymal cells were 7.24% and 2.22%, respectively. The longitudinal swellings of the fibers and parenchymal cells were 0.62% and 1.24%, respectively. The fibers had a higher transverse swelling rate than that of the parenchyma cells.

Water vapor sorption behavior of bamboo pertaining to its hierarchical structure

Bamboo is an anisotropic, hierarchical, and hygroscopic material. Moisture transport in bamboo is one of the most fundamental properties affecting almost all other physical and mechanical properties of the material. This study investigated the water vapor sorption behaviors of bamboo at various structural levels: cell walls, cells (with pits) and bamboo blocks. The specimens with two sorption directions, longitudinal (L) and transverse (T), were measured by saturated salt solution method and dynamic vapor sorption. The parallel exponential kinetics model was used to analyze the sorption kinetics. The results showed that at the cell wall level, the sorption rate and equilibrium moisture content (EMC) of cell wall in the L specimens were larger than those in the T specimens. The differences were probably caused by the looser cell wall layers in the L specimens. At the cellular scale, pits in the cell wall resulted in an enhanced sorption rate and EMC of the T specimens compared with the L specimens where the pits in the parenchyma cells were only distributed in the lateral walls but not in end walls. At the macro scale, the sorption rate and moisture content of bamboo blocks were largely controlled by the vessel cells. As a hierarchically-structured plant, bamboo performs the biological function of moisture transport at all these scales. This work helps improve the understanding of water transport behavior in bamboo, which may lead to better bamboo drying and impregnation processes.

Creation and structural evaluation of the three-dimensional cellulosic material “White-Colored Bamboo”

Abstract This study reports a new cellulosic material that maintains the original three-dimensional structure of bamboo and is produced by optimization of chemical treatments. Bamboo blocks were prepared from the current year culms of moso bamboo (Phyllostachys edulis) and subjected to three chemical treatments alone or in combination. Based on the color changes and Fourier transform infrared spectra, the combination of alkaline treatment with alcoholysis followed by Wise method was found to be an optimal treatment method. This serial treatment caused the blocks to become completely white and removed non-cellulosic components such as hemicellulose and lignin from the cell walls of the parenchyma as well as those of vascular bundles. This sample was named as “White-Colored Bamboo.” Extensive structural evaluations from anatomical- to nano- level were performed using X-ray computed tomography, X-ray diffraction, and transmission electron microscopy incorporated with the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation technique. These multiple observations showed that the white-colored bamboo maintained its inherent hierarchical structure, thus encouraging to produce functional biomaterials.

Increased strength of laminated bamboo beams using a shear connector adhesive method

At this time the timber with good quality has been difficult to obtain, so the wood is increasingly rare for building construction. To reduce deforestation due to logging for construction materials, it is time to replace wood with bamboo. Laminated bamboo is an engineering building material that has a character like wood. Laminated bamboo structures can encourage the replacement of wood, steel and concrete materials so that the development of laminated bamboo technology can revolutionize the use of bamboo in construction. One of the weaknesses of the laminated bamboo beam structure is the adhesive line between the bamboo lamina. Mechanical lamination using a shear connector prevents horizontal slip between the bamboo lamina. Incising method is a method that makes the adhesive as well as the adhesive as well as the shear connector. Dendrocalamus asper research material with an average age of 4 years. The testing shear strength and tensile strength of bamboo block lamination was carried out based on ASTM D143 (2002). Experimental testing of flexural strength of laminated bamboo beams is carried out using a tool with a Multi Purpose Testing System and data logger. Changes in the structure of bamboo that are applied to lateral pressure are observed using SEM (Scaning Electron Microscopy). The use of Incising method in making laminated bamboo beams can significantly increase the strength of mechanical properties laminated beam structures.

Insecticidal activities of three weed varieties against the Bamboo Powder Post Beetle <i>Dinoderus minutus</i> Fabricius (Coleoptera: Bostrichidae)

The insecticidal activities of crude ethanol extracts of leaves of three weed species, Siam weed, Chromolaena odorata Linn., Milk weed, Euphorbia heterophylla Linn. and Tree Marigold Tithonia diversifolia (Hemsl.) A, Gray on the insect, Dinoderus minutus Fabricius, were investigated on bamboo as substrate. Bamboo blocks were treated with different concentrations: control (positive), control (negative), 20% and 25% of each plant extracts. Twenty-five active adult D. minutus insects were introduced into each setup of five bamboo blocks in 0.32 L jars for 60 days and were replicated four times in a Completely Randomized design in the laboratory. Data were collected on mortality of D. minutus at 5, 10 and 15 days after introduction. The number of holes bored by D. minutus on bamboo blocks after 60 days of storage were counted and the percentage weight loss of bamboo block was calculated using standard procedure. The result showed that the highest and the lowest percentage mortality of D. minutus were recorded in 25% T. diversifolia (94.67±2.67) and control (–) respectively at 15 days after treatment. The number of holes bored by D. minutus on bamboo blocks in the control treatments was higher than the number of holes bored on bamboo blocks treated with different concentrations of the three extracts. The mean percentage weight loss of bamboo blocks obtained at 20% and 25% concentrations of each extract was lower than that of the two control treatments. The maximum wood protection (1.33±0.22) against D. minutes was recorded at 25% concentration of T. diversifolia. The number of D. minutus holes on bamboo block correlated positively (R2 = 0.538; p<0.0001) with the percentage weight loss of bamboo. The three weeds at 20% and 25% concentrations could be used in the management of D. minutus on bamboo.Keywords: Plant extract; Dinoderus minutus; bamboo pest; mortality; weight loss.

Axial compressive behavior of Moso Bamboo and its components with respect to fiber-reinforced composite structure

Bamboo is a unique fiber-reinforced bio-composite with fibers embedded into a parenchyma cell matrix. We conducted axial compression tests on bamboo blocks prepared from bottom to top, and from inner to outer portions of the culm. The apparent Young’s modulus and compressive strength of whole thickness bamboo blocks exhibited slight increases with increasing height along the culm, due to slight increases of fiber volume fraction (Vf) from 28.4 to 30.4%. Other blocks showed a significant increase in apparent Young’s modulus and strength from the inner to outer part of the culm wall, mainly owing to a sharp increase of Vf from 17.1 to 59.8%. With a decrease of fiber fraction volume there was a transition from relatively brittle behavior to very ductile behavior in bamboo blocks. Results indicated that stiffness and strength of bamboo was primarily due to fiber in compression, and ductility of bamboo was provided by the parenchyma cell matrix acting as a natural fiber-reinforced composite.

Enzymatic biocatalysis of bamboo chemical constituents to impart antimold properties

Current antimold agents that capitalize on broad spectrum biocidal toxicity for their efficacy can create potential hazards in the environment, as in many cases these biocides are not chemically bonded to the wood. They can therefore leach into the ecosystem to jeopardize off-target organisms. In this study, “bio-catalysis” of potassium iodide (KI) was used to impart non-diffusible antimold properties to 4-year-old bamboo, and the mechanisms of how this system works against Aspergillus niger and Trichoderma viride fungi were also studied. In addition to the bamboo block material tested, powdered samples of lignin, cellulose and hemicellulose were studied to better understand binding of iodide to the chemical subcomponents of the bamboo cell walls. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses were used to investigate the sample chemistries and antimold mechanisms, respectively. The results revealed that a specific ratio of laccase enzyme with a laccase-mediator functioned best in binding KI to bamboo. Lignin samples showed the greatest changes in FTIR, especially relative to the methoxyl groups and aromatic skeleton. Additionally, enzyme activity on lignin moieties showed much more differences than on hemicellulose and cellulose after biocatalyzed KI modification. Moreover, the XPS binding energy readings of 621.1 and 632.7 eV (Aromatic region) for lignin were consistent with I–C binding associated with its phenolic structures. While the 620.7 eV (Aliphatic region) suggested I–C bonding that associated with residual lignin in hemicellulose, no peaks were observed for the iodine 3d XPS spectra of treated cellulose. XPS analyses of the O/C and C1/C2 ratios revealed that the formation of I–C bonds was likely due to the substitution of oxygen-contained groups which were formed from laccase-catalyzed oxidation. Thus, enzyme-catalyzed formation of I–C bonds with bamboo chemical constituents is a highly effectual, as well as an ecological method to protect bamboo against mold colonization in the present research.

Compressive failure mechanism and buckling analysis of the graded hierarchical bamboo structure

Bamboo is a unique unidirectional biocomposite, which consists of vascular bundles (VBs) as the reinforcement and parenchyma cells (PCs) as the matrix. The non-uniform distribution of VBs embedded in the matrix makes bamboo a functionally graded material. In order to investigate the compressive behavior of bamboo as a function of its components, compression tests were performed on specific bamboo samples with different VB volume fraction (V vb), collected from different positions in the culm wall. The results show that both compressive strength and modulus increased linearly with V vb, while the plastic deformation of samples in the compression decreased with increasing V vb. This indicates that VBs dominate the compressive strength and modulus of bamboo, while the ductile performance of the bamboo is determined by the foam-like PCs. Scanning electron microscope observation indicated that VBs buckling were the main cause of failure. The Euler theory was applied to investigate the buckling behavior of bamboo blocks, showing that theoretical buckling strength when only considering the effect of VBs was much lower than with the test results, with the theoretical buckling strength being closer to test results when considering both the effect of VBs and PCs. It is therefore necessary to consider the contribution of PCs to resist buckling in bamboo, as their foam-like structure can effectively prevent the large-scale buckling of VBs.

Study on Compressive Strength of Bamboo-Aluminum Composite

The advantages of aluminum alloy are found expression in lightweight and high strength, while bamboo features in density and thermal insulation. It’s necessary to explore composition effect of bamboo-aluminum composite. Specimens were prepared by filling aluminum alloy hollow profile with bamboo blocks, and then stress-time curves were collected in process of compression. Its ultimate strength reached 56 MPa, and residual strength is about 40% of its ultimate strength. The bamboo-aluminum composite has good mechanical properties and reliability for structural components and is worthy of wide applications.

Study of moso bamboo’s permeability and mechanical properties

In this article, moso bamboo blocks were first treated with hydrochloric acid solvents with different concentrations or microwave treatments with various microwave output power and treatment durations. The results showed that the crystalliferous region of cellulose of moso bamboo blocks formed porous or swelling type structures under hydrochloric acid pretreatment conditions; the mechanical strength of the moso bamboo decreased when the percentage of hydrochloric acid pretreatment solvents increased from 0 to 3%. When the moso bamboo blocks were treated with microwave, the internal water was transformed into steam, and the water vapor destroyed the cell walls of the vessel, sieve tube, and parenchyma cells in the moso bamboo block, resulting in a significant improvement in the permeability of moso bamboo. In order to ensure that the moso bamboo samples did not burn by microwave heating, the samples had to be immersed in water. The process of water gasification inside the Moso bamboo was not violent. Therefore, the mechanical strength of the moso bamboo had decreased only slightly, and a weak relationship was found between the mechanical strength of the moso bamboo samples and the microwave treatment durations.

Study on the Mould-Resistant Properties of Moso Bamboo Treated with High Pressure and Amylase

Starch of moso bamboo mainly exists in the elongated parenchyma cells, and it is difficult for amylase to enter moso bamboo and dissolve the starch. Therefore, the mould resistance capability of moso bamboo’s products cannot meet the need for bamboo to resist fungal decay. In this experiment, moso bamboo blocks were first treated at six levels of pressure and for six different treatment durations. The results showed that reducing sugar content was decreased dramatically from 0.92 mg/L to 0.19 mg/L and the starch content decreased from 1.18% to 0.96% when the pressure was increased from 0 psi to 100 psi. Regression analysis showed that the effects of an individual amylase reaction and individual pressure treatment on the starch or reducing sugar content were significant with a high correlation coefficient. Three traditional types of moso bamboo moulds (Aspergillus niger, Penicillium citrinum, and Trichoderma viride) were then used for mould resistance testing. The results revealed that the mould resistance capability of moso bamboo blocks could be greatly improved by the combined effect of enzyme activity and pressure treatment. Mould resistance was enhanced by increasing the pressure or prolonging the treatment time. This research could provide a new method for the protection of bamboo from mould attack.

Pengaruh Pola Susunan Laminasi Balok Bambu Tali (Gigantochloa apus Kurz) terhadap Kerapatan, Delaminasi dan Keteguhan Patah

Effect of Lamination Pattern of Tali Bamboo (Gigantochloa apus Kurz) Beam on Density, Delamination, And Rupture StrengthBamboo is a potential species as its price is relatively less expensive than wood logs while it also represents a fast growing plant and is easy to plant. In general bamboos in South Kalimantan have not been exploited optimally. Its utilization for construction purposes is very limited. This study aims to identify the effects of lamination pattern on the density, delamination and rupture impregnability (Modulus of Rupture, MoR) of laminated bamboo blocks, with the combinations of a (reed wall- reed wall), b (reed wall-husk), and c (husk- husk and reed wall-reed wall). The results showed that lamination patterns affected the density, delamination and rupture impregnability of the laminae produced. The average density (kg/cm3) is 0.5321, 0.6923, and 0.6746 for treatments a, b, and c respectively. Delamination percentage (%) is 6.55, 16.65, and 21.1, while the rupture impregnability level (kg/cm2) is 228.99, 152.09,and 171.97 for treatments a, b, and c respectively. Delamination percentage of less than 10% suggets that the laminae produced can be used for building construction. that It is concluded that lamination pattern of reed wall-reed wall gave the best performance of bamboo lamina with the average density of 0.5321 kg/cm3, the delamination percentage of 6.55% , and the rupture impregnability level of 228.99 kg/cm2.

Tensile properties of Moso bamboo (Phyllostachys pubescens) and its components with respect to its fiber-reinforced composite structure

Bamboo is a fiber-reinforced bio-composite since its culm wall is mainly composed of parenchymatous ground tissue in which vascular bundles are embedded. In order to analyze the mechanical properties of bamboo as a function of its components, tensile tests were performed on bamboo blocks and the corresponding volume fractions of fiber and parenchymatous ground tissue were measured. More significant linear relationships were found between tensile properties and volume fractions of the bamboo components. The tensile strength and modulus of elasticity of bamboo fiber and parenchymatous tissue were estimated according to the linear equations obtained by regression analysis. The macrographs of fractured bamboo blocks and the micrographs of fracture surfaces obtained by scanning electron microscope were also analyzed. Further tensile tests on separated bamboo fiber bundles were analyzed. Results show that the tensile strength of bamboo fiber obtained from the tests on bamboo blocks was higher than that on separated fiber bundles. This might be due to the interaction between components in bamboo in which parenchymatous ground tissue can pass loads and distribute the stresses loaded on fibers.

Improvement of softening treatment technology of bamboo

In order to improve the efficiency of softening bamboo block when manufacturing bamboo veneer, chemistry reagents such as NaHCO3 are often adopted during bamboo softening treatment. But the results of Fourier transform infrared spectroscopy (FTIR) showed that the band intensity at 1,733 cm−1, assigned to C=O stretching vibration in xylan, was reduced in the spectrum of softening-treated bamboo with NaHCO3 compared with that of not softening-treated bamboo and softening treatment of bamboo without NaHCO3. That is to say, that the hemicellulose of bamboo was destroyed after softening treatment with NaHCO3, which meant that softening treatment of bamboo with NaHCO3, is not a perfect softening treatment method. Thus, in this paper a softening technology at 120°C for 30 min in a closed container was adopted. The results of FTIR show that there was almost no difference in FTIR spectra between no softening treatment of bamboo and softening treatment of bamboo at 120°C for 30 min, which meant that softening treatment at 120°C for 30 min had no effect on the composition of bamboo. The results of dynamic mechanical analysis (DMA) show that T g of not softening-treated bamboo was 120°C, while T g of softening-treated bamboo at 120°C for 30 min was 88°C. T g of softening-treated bamboo at 120°C for 30 min decreased by 26.7% compared with that of not softening-treated bamboo. The results of hardness show that the hardness of bamboo strip after a softening treatment for 30 min at 120°C decreased by 42.0–54.6% compared with that of not softening-treated bamboo. The results of hardness and DMA show that the effect of softening treatment of bamboo at 120°C for 30 min was resultful.