A novel method for measuring mechanical properties of vascular bundles in moso bamboo

Bamboo is a composite material reinforced axially by fibers called vascular bundles. In this paper, the mechanical stripping method was used to isolate vascular bundles from moso bamboo (Phyllostachys edulis), China's most important commercial bamboo species. The paper focuses on analyzing the suitability of this method for measuring the mechanical properties of single vascular bundles with respect to their location within a bamboo culm. Using a confocal laser scanning microscope (CLSM) and video extensometry testing technique, we found that the tensile mechanical properties of vascular bundle can be determined with great accuracy. The method relies on mechanical stripping to prepare samples at a length scale from individual bamboo, which traditionally increases the difficulty of conducting tests. Therefore, to determine the elastic modulus of vascular bundle material, video extensometry was used for efficient strain detection in tensile experiments. This type of sample preparation minimizes the usual problems encountered when mounting samples. The cross-sectional area of the vascular bundle was determined by CLSM measurement using an ultramicrotome as a cutting tool. Applying this method, the elastic modulus and tensile strength of the vascular bundle of moso bamboo were measured to be similar to 44.67 GPa and similar to 709.96 MPa, respectively. It is noteworthy that the tensile mechanical properties of the fibrous sheath areas are higher than those observed over the whole area.