A review of extraction and characteristics of bast fibres

Bio-based products have many merits compared to traditional products, comprising low cost, low density, and biodegradability. Bast fibres are potential to be one of the main components of bioproducts. Although many papers have been published focusing on bast fibres, none of them has reviewed all approaches applied to extract bast fibres, and properties of bast fibres. This study presents detail characteristics of common bast fibres, including hemp, flax, kenaf, ramie, and jute, and all strategies that have been employed to extract these bast fibres. In summary, mechanical decortication and retting are the two main methods for bast fibre extraction. The main challenge of decortication is fibre wrapping around the rotating machine parts, and low fibre purity. Post-decortication cleaning is necessary to increase fibre purity. However, it is difficulty to remove shives from fibres, due the tangling nature of bast fibre. Properly designed retting process can produce high purity fibre; however, the main drawback is the generation of wastewater. Properties of bast fibre are highly variable, depending on the chemical composition and the environment conditions. Promising characteristics of bast fibres are low density and reasonably high mechanical properties which make them suitable to replace synthetic fibres; however, low thermal stability, hydrophilic properties, and low free surface energy of bast fibres are weak attributes for bioproducts. Technology is required to be developed to address the challenges for bast fibre extraction and the undesired properties of bast fibre.