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

Abstract

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.

Bamboo as Sustainable Building Materials: A Systematic Review of Properties, Treatment Methods, and Standards

“…The failure mode is also a general concern in bamboo specimens tested in axial loading. Zhou et al [54] observed a ductile failure characteristic in Phyllostachys edulis bamboo tested in parallel to grain, similar to the observation of Cui et al [11] on bamboo fiber bundles. Basically, the common mode of failure of bamboo culms tested in parallel to the grain is splitting and end bearing [14,45,82,85].…”

“…Krause et al [10] mentioned that the tensile behavior of Dendrocalamus gigantus is dictated by the fiber volume fractions and independent of the position of the culm wall. Cui et al [11] observed that the tensile strength of bamboo fiber bundles gradually decreases with increasing temperature, which is mainly influenced by the decrease in the relative content of cellulose and hemicellulose. Wu et al [12] confirmed that the tensile strength of an outer bamboo sliver treated with alkali at 60 • C and an inner bamboo sliver treated with alkali at 40 • C will increase up to a maximum of 86.6% and 132%, respectively, compared to untreated bamboo.…”

Effect of processing temperature and polymer types on mechanical properties of bamboo fiber composites

“…The mass loss increases with increasing temperature with significant mass loss observed at holding temperature above 250 °C. The high temperature processing resulted in the thermal degradation of fiber structure, loosening of the cell wall, and generation of pores (Cui et al 2023). Furthermore, tensile tests were performed to investigate the changes in mechanical properties of the bamboo fiber, with results shown in Fig.…”

Quasi-ductile fracture behavior of glubam due to transverse fiber distribution

“…Glubam [13][14][15][16] LBL [17][18][19] Douglas Fir [20] WPC [21] Tensile Due to the mechanical properties [27][28][29][30][31][32][33][34] of the fiber are obviously superior to those of the matrix, there are significant differences in the fracture characteristics of bamboo fibrous composites along and perpendicular to the fiber direction. In addition, this difference is influenced by the distribution of fibers, showing a more complex mode of variation.…”