In-depth study of the microstructure of bamboo fibres and their relation to the mechanical properties

The mechanical properties of bamboo technical fibre, from the species Guadua angustifolia, have been studied showing values of strength up to 800 MPa and E-modulus up to 43 GPa, proving their adequate tensile properties that make this natural fibre suitable as reinforcement in composite materials. To fully explore the good mechanical properties and to make an adequate use of this new reinforcement, it is indispensable to comprehensively understand the fibre behaviour as a function of the microstructure. Microscopic observations have provided us with an extensive knowledge of the complex microstructure of this natural fibre from the macroscale down to the microscale level where different features like the distribution of the elementary fibres within the fibre bundle, dimensions and layering pattern of the elementary fibres and the main microfibrillar angles could be measured. The Young’s modulus of the elementary fibre is analysed based on the micromechanics of composite materials, commonly used for unidirectional short fibre composites, and the fibre microstructure. The predicted results are in reasonable agreement with experimental data, showing the appropriateness of the model for describing the elementary fibre stiffness. Also, the failure modes of single fibres after tensile testing are analysed by microscopic observations, to have an indication of the stress development in the elementary fibres and the different failure mechanisms.