Change in Micro-Morphology and Micro-Mechanical Properties of Thermally Modified Moso Bamboo

Investigation of mechanical, physical and thermoacoustic properties of a novel light-weight dense wall panels made of bamboo Phyllostachys Bambusides

This study was conducted to evaluate the properties of lightweight sandwich panels made from low diameter bamboo particles, Phyllostachys Bambusides collected from Gilan province, Iran, as core layer, combined with thin wall bamboo strips as faces. The effects of three individual variables such as density of core layer (350-550 kg/m3), resin consumption in core layer (7.5-9.5%) and resin consumption in faces (175-275 g/m2) on some important physical, mechanical and thermos-acoustic properties of the panels were investigated. Response surface methodology was used to statistically analyse the results and optimization process. The average values for the mechanical properties of the sandwich panels were obtained as 17.16 MPa, 5669 MPa, 0.02 MPa, 17.60 MPa, 1.83 MPa, 0.03 MPa, and 913.3 MPA for modulus of rupture, modulus of elasticity, internal bonding, compression strength parallel to face grain, compression strength perpendicular to face grain, shear strength, and screw holding, respectively. Finally, thermal conductivity and noise reduction coefficient of the panels were respectively gained as 0.01 W/mk and 0.31. The results of technical and thermo- acoustic properties of the panels showed that the light weight sandwich panels from bamboo residues would be a suitable and sustainable alternative as an insulation material for sustainable and green construction.

Effects of Thermal Treatment on the Mechanical Properties of Bamboo Fiber Bundles

Bamboo is known as a typical kind of functional gradient natural composite. In this paper, fiber bundles were extracted manually from various parts of the stem in the radial direction, namely the outer, middle, and inner parts. After heat treatment, the mechanical properties of the fiber bundles were studied, including the tensile strength, elastic modulus, and fracture modes. The micromechanical properties of the fiber cell walls were also analyzed. The results showed that the mean tensile strength of the bamboo fiber bundles decreased from 423.29 to 191.61 MPa and the modulus of elasticity increased from 21.29 GPa to 27.43 GPa with the increase in temperature. The elastic modulus and hardness of the fiber cell walls showed a positive correlation with temperature, with the modulus of elasticity and the hardness increasing from 15.96 to 18.70 GPa and 0.36 to 0.47 GPa, respectively. From the outside to the inside of the bamboo stems, the tensile strength and elastic modulus showed a slight decrease. The fracture behavior of the fiber bundles near the outside approximates ductile fracture, while that of the bundles near to the inside tend to be a brittle fracture. The fracture surfaces of the bamboo bundles and the single fibers became smoother after heat treatment. The results show that bamboo fiber bundles distributed near the outside are most suitable for industrial development under heat treatment at 180 °C. Therefore, this study can provide a reasonable scientific basis for the selective utilization, functional optimization, and bionic utilization of bamboo materials, which has very important theoretical and practical significance.

Study on Bamboo Longitudinal Flattening Technology

In this paper, we introduced a bamboo longitudinal flattening technology and analyzed the effects of the softening–flattening process on the physical and mechanical properties of moso bamboo. This is a newer bamboo processing technology that can enhance the utilization and reduce pollution compared with traditional bamboo-based products. Results showed that the parenchyma cells distorted and compacted due to the flattening process. The hemicellulose and cellulose content decreased, while the content of lignin presented an increasing tendency. As expected, the dimensional stability of moso bamboo enhanced due to the decrement of hemicellulose. The softening–flattening process positively contributed to the micro-mechanical properties of treated bamboo specimens. For example, the hardness and modulus of elasticity of the untreated bamboo sample increased from 0.58 and 15.7 GPa to 0.8 and 17.5 GPa, respectively. In addition, the changes in cellulose crystallinity and mechanical properties were also investigated in this paper. The cellulose crystallinity increased from 37.5% to 43.2%, significantly. However, the modulus of rupture of the flattened bamboo board decreased from 9000 to 7500 MPa due to the grooves made by the flattening roller. The MOE of flattening bamboo board showed the same decreasing tendency.