Effect of bamboo unit morphology on the preparation of bamboo fibers by steam explosion

Steam explosion is an attractive technology due to its low energy consumption and low environmental impact; however, there is still relatively limited research to improve the extraction efficiency of bamboo fibers. Here, the effects of the morphology of bamboo units on the extraction efficiency of bamboo fibers by steam explosion were fully examined. Based on the differences in morphology of raw materials, five types of bamboo units (bamboo strip, tangential bamboo sliver, radial bamboo sliver, bamboo bundle, and bamboo particle) were selected for steam explosion treatment. The characteristics of bamboo units and the resulting bamboo fibers as well as extraction efficiency were investigated by scanning electron microscopy, specific surface area analysis, fiber yield and aspect ratio calculation, color difference analysis, infrared spectroscopy, and tensile testing. Moreover, the mechanisms behind the improvement in the extraction efficiency of fibers from bamboo units have also been explored. The results showed that the unit morphology of raw materials greatly influenced the preparation of bamboo fibers by steam explosion. The effective fiber yield of bamboo bundles could reach 60.85%, which was 42.51% higher than bamboo strips. The tensile strength and modulus of steam exploded fibers from bamboo bundles could be as high as 531.79 MPa and 23.15 GPa without compromising the fiber properties too much. This is because the specific structure of bamboo bundles was able to facilitate the entry of steam for fiber separation without causing excessive damage to the fibers, showing the most effectiveness. The improvement of the extraction efficiency of steam explosion through tuning the properties of bamboo units is conducive to the cost-effective and efficient preparation of controlled-form bamboo fibers. The results in this work provide fundamental information for the further utilization of fiber extraction by steam explosion.