Enzymatic approach to accelerate the permeability and adhesion of raw bamboo epidermis

Raw bamboo possesses wax layer, which endows the surface hydrophobic property but makes the anti-fungal chemicals enter difficultly. In this work, lipase was utilized to remove the wax layer from bamboo epidermis for increasing the permeability of raw bamboo. The lipase treatment was optimized as 24 h reaction in buffer solution with a pH value of 8.5 and a temperature of 40 ℃. The weight percentage gain (WPG) of water characterizing the permeability of raw bamboo was used to evaluate the treatment effect. In addition, the bonding strength of bamboo surface was assessed using epoxy resin to further investigate the effect of lipase treatment. Compared with untreated bamboo, WPG increased to 14.7% after 72 h, and the bonding strength improved from 0.01 MPa to 0.73 MPa. The phenomenon could be explained by the diminished contact angle of bamboo epidermis, which decreased from 102.4 °to 73.5 °. An in-depth study on how lipase improves the permeability of bamboo epidermis was investigated using the GC-MS, TG, and DSC analyses. This work provides a green processing method to increase the permeability of bamboo epidermis, which will be beneficial for enhancing the fungal and cracking resistance of raw bamboo through chemical impregnation or modification.