A method of calculating the mechanical properties of nanoscopic plant cellwall components from tissue properties

Biological tissues are made from nano-composite materials and given the rec ent interest in manufacturing synthetic nano-composites an analysis of natu ral nano-composites seems a worthwhile exercise. There is also potential fo r extracting natural nano-fibres and using them as reinforcements in other materials. In this paper a hierarchical mechanical model is formulated to d escribe potato tuber tissue and the model is used to back calculate the pro perties of cell wall nano-fibres. The model contains two structural levels, the cell structure and the cell wall structure. Material properties are as signed at the level of cell wall microfibrils (nano-composite fibres). Forc e deflection data from the compression of cubes of potato tissue were fed i nto the model and the properties of the cell wall microfibrils predicted. T he modulus was found to vary with strain, but had a maximum value of 130 GP a, which is close to predictions from theoretical chemistry for the stiffne ss of cellulose microfibrils. At 8% wall strain (the value at which failure s were suspected to begin), the stress was predicted to be 7.5 GPa which is also close to theoretical chemistry predictions for the strength of cellul ose microfibrils. The large strains and decreasing stiffness indicate the i nfluence of polymers other than cellulose. (C) 2000 Kluwer Academic Publish ers.