Destructuration of cotton under elevated pressure

Dry and wet cotton linters were compressed under elevated pressure in a home-made Bridgman anvil press designed to reach 2.5 GPa and 180 °C. The structural organisation of cotton was changed under the joint action of temperature and pressure. Cotton having high moisture content shows that only a thin surface layer is partially destructured to a compact mat of nanofibres, while the initial cotton fibres are only deformed inside the sample. For dried cotton, the whole sample undergoes a destructuration into a compact mat of nanometre-sized fibres. The mechanical properties were studied by nano-indentation and dynamic mechanical analysis. Compressed dry cotton has higher modulus (10.3 GPa) than wet cotton (6.8 GPa). We postulate that the transverse elastic modulus of cotton microfibrils is around the value of 10 GPa. This work showed that nano-sized fibrils can also be separated in the solid state without flow, and re-compacted to form a solid object.