Comparison of the fabrication process and macro and micro properties of two types of crack-free, flatten bamboo board

The crack-free flattened bamboo board can be fabricated by using high-pressure saturated steam followed by a flattening process. With the application of “notched flattening technology”, the flattened bamboo board can be obtained with a large width and limited length. However, this technology causes the formation of nail holes in the bamboo surface, resulting in the deformation concerning the appearance and mechanical properties of bamboo products. On the other hand, “non-notched flattening technology” can yield flattened bamboo board with a 3.5-m total length without nailing holes on bamboo surface. The present study investigates the fabrication processes, chemical composition, microstructure, cell-wall mechanical properties of bamboo boards, and their practical applications. The obtained results showed that the contents of hemicellulose and cellulose were decreased due to heat treatment. Moreover, the flattening process caused the compression and squeezing of parenchyma cells that were evident through microstructure analysis. Thus, the density and EMC improved due to the flatting process. The improved density and crystallinity degree had a positive impact on the nano-mechanical properties of the bamboo cell wall. The modulus of elasticity and hardness of the control had been increased from 17.3 GPa and 0.49 GPa to 21.2 GPa and 0.73 GPa (non-notched flattened bamboo board), respectively. The improvement in the bamboo cell-wall mechanics had contributed positively to the macro and physical properties of the flattened bamboo board. Furthermore, the introduction of these two types of manufacturing processes of the crack-free flattened bamboo board demonstrates their applications in producing the different types of flattened bamboo board.