Isolation of Nano Fibres from Hemp and Flax ...

Agricultural feed stocks are one of the readily available and inexpensive lignocellulosic feed stocks for preparing cellulose nano fibrils. The very common method for isolation and separation of cellulosic fibrils from these feed stocks include successive physicochemical techniques. In this paper, a mild chemical treatment was used to remove pectinic substances and lignin, following a mechanical defibrillation using a commercial grinder to isolate nano fibres from agricultural fibres such as flax and hemp. The defibrillation process was optimized based on the strength properties of the nanofibril films. The generated nano fibres have a diameter distribution in the range of 20-100 nm with 80% fibrils in the range of 20-60 nm. The tensile strength and the modulus of the nano papers were 180-200 MPa and 9-11 GPa compared to 100-95 MPa and 5-6 GPa respectively for hemp and flax. The study showed that, the nano papers can impart high strength even in the presence of hemicelluloses present ed in the fibre bundle indicating removal of hemicelluloses to very low extent using intensive chemical treatments which may not be required for feed stocks with fewer amounts of hemicelluloses, such as agricultural fibres. To exploit the strength properties and reinforcing potential of these nano papers, composites were prepared with polycarbonate. The prepared modulus of the composites showed a significant improvement at a fibre loading of 13 wt%.