In China, bamboo is a symbol of longevity and vitality, able to survive the hardest natural conditions and remain green all year round. In a storm, bamboo stems bend but do not break, representing the qualities of durability, strength, flexibility and resilience1.
Bamboo is a traditional construction material in Asia. Its strength and flexibility arise from its hollow stems (‘culms’) made from distinct material components. The solid outer shell of the culm is made primarily from longitudinal fibres. A higher density at the outer wall makes it stronger than the inner regions, and results in remarkable stiffness and flexural strength. Running through the centre of bamboo stem are parenchyma cells that store and channel the plant’s nutrients.
At the micro-/nano-scale both the fibres and the matrix contain cellulose nano-fibrils of the same type. However, the structural arrangement of the two materials result in contrasting mechanical properties. Individual fibres may reach a strength of 900 MPa, whilst the matrix can only resist about 50 MPa. There is also a considerable difference in their elastic properties, with the fibres being much stiffer than the matrix.
Bamboo is often treated with alkaline solutions, to modify these properties. Alkaline treatments can turn this rapidly renewable and low-cost resource into soft textiles, and extract fibres to be used in composite materials or as biomass for fuel.
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Image: Dr Enrico Salvati on the B16 beamline at Diamond.