Bamboo slivers with high strength and toughness prepared by alkali treatment at a proper temperature

Abstract

Despite bamboo slivers having long been used to manufacture bamboo weaving products, the flexibility is still well below satisfactory, especially for those split from inner layer of bamboo culm. Here, a facile approach was reported to obtain strong and flexible bamboo slivers, in which the slivers from the outer and inner layer of bamboo culm were processed with 5 wt% alkali treatment at various temperatures (23, 40, 60, and 80 °C), respectively. Compared with untreated bamboo slivers, the treated ones were investigated in terms of the microstructure, chemical composition, morphology, tensile and bending performances. The results showed that tensile and bending properties of all treated bamboo slivers were significantly improved, especially for those from inner layer of bamboo culm. The tensile strength of outer bamboo sliver treated at 60 °C and the inner ones treated at 40 °C increased up to the maximum, respectively, increasing by 86.6% and 132.0% compared with the untreated ones. The highest flexibility of the outer- and inner bamboo sliver can be achieved at 80 °C and 60 °C alkali treatment, respectively. The slivers can be completely wound around a nylon rod with a diameter of 10 mm without fracture. The excellent tensile and bending performance of bamboo slivers alkali-treated at proper temperature was largely attributed to tightly cellulose molecule aggregating induced by substantially increasing hydrogen bonding after the partial removal of lignin and hemicellulose. A denser and interlocking cellular structure due to the collapse of parenchyma cells after alkali treatment at proper temperature also partly contributed to the increased tensile and bending strength. The results suggest that strong and flexible bamboo slivers can be prepared by one-spot alkali treatment at a proper temperature, which may widen the application scope of bamboo slivers.