Observation of the fundamental properties of bamboo pith ring

Bamboo pith ring (BPR) is regarded as a particular tissue affecting bamboo processing and is usually discarded, resulting in waste and low utilization of bamboo. To improve the utilization of bamboo and make full use of BPR, the fundamental properties, including morphology, chemical properties, and mechanical properties of BPR by confocal laser-scanning microscope, SEM, IR-image, and nanoindentation, were investigated in this study. On the macroscale, the stone cells in BPR are round or square and closely arranged, and the average thickness of BPR is 404.6 μm. On the cell scale, with the increase in distance from the pith cavity, stone cells show different shapes and sizes. On the cell wall scale, the stone cell in BPR show a multi-layer structure with alternating thick and thin walls, and there are dense pits on the wall layer. Stone cell is mainly composed of cellulose, hemicellulose, and lignin, and hemicellulose and lignin contents are higher than parenchyma cell. The elastic modulus and hardness of the stone cell wall were 6.98 GPa and 491.8 MPa, respectively. Studying BPR morphology, chemical, and mechanical properties are expected to lay a foundation for, among others, bamboo gluing, mechanics research, and drying cracking.