The microstructure of Moso bamboo (Phyllostachys heterocycla) with tung oil thermal treatment

Bamboo has a natural anisotropic porous structure. Previous studies have shown strong correlations between the properties and microstructure of bamboo. In this study, we examined the microstructure of Moso bamboo to reveal the mechanism of enhanced properties with tung oil thermal treatment. The morphological and chemical microstructure of Moso bamboo were characterized using scanning electron microscopy (SEM) and Raman spectroscopy. We found that tung oil film presented in the cell wall, cell lumen, and intercellular space after tung oil thermal treatment, which could decrease the water permeability in the cell wall. Additionally, the pits in vessels showed significant shrinkage in the short-axis orientation with thermal treatment in tung oil, and the shrinkage rate was nearly 50% with a temperature of tung oil over 140°C, which prevented the transportation of water through the pit. The content of tung oil in bamboo was reduced by more than 50% with an increase of tung oil temperature from 140°C to 200°C, which further supported the results of changed bamboo morphology. Altogether, these findings offer further support for the enhanced hydrophobic property of bamboo after tung oil thermal treatment.