Chemical composition and thermal stability of cells in different structures of Phyllostachys edulis

  Objective  The macrostructure and physiological functions between the internode and node of Phyllostachys edulis are quite different. Fibers and parenchyma cells are the two main components in either Phyllostachys edulis internodes or nodes, full comparison and understanding of the differences between fibers and parenchyma cells in terms of structures and properties can provide a theoretical basis for their directional separation and efficient utilization.

  Method  The fibers and parenchyma cells in both bamboo internodes and internodes were isolated by physical and chemical separation methods. Subsequently, the chemical composition, thermal stability, and microstructure of bamboo fibers and parenchyma cells were studied by Fourier infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and field emission scanning electron microscopy.

  Result  The morphology of the ends of fibers extracted from the internodes and the bamboo nodes both exhibited sharp and slender shapes. As for parenchyma cells, the long cells and short cells could be clearly distinguished in the internode, while the parenchyma cells in the node showed round, oval, or square cell shapes. The content of cellulose in the internode was higher than that in the node, and the content of lignin in the internode was lower than that in the node, but the hemicellulose content was not significantly different between the internode and the node. The cellulose content in fibers was higher than that in parenchyma cells, the lignin content in fiber was lower than that in parenchyma cells, and the hemicellulose content in fiber was not different from that in parenchyma cells. With respect to thermal stability, the maximum decomposition temperature in internode parenchyma cells was lowest at 390.32 ℃, and the maximum decomposition temperature in node fiber was highest at 393.54 ℃.

  Conclusion  The fiber morphological difference between the internode and the node of bamboo is not very significant. The parenchyma cells in the internode can be divided into long cells and short cells, but distinguishing between long cells and short cells in the node is not obvious. The cellulose and lignin contents are different in fiber and parenchyma cells at different locations, but the hemicellulose contents are not different. The thermal stability of fiber and parenchyma cells in the bamboo node is slightly higher than that in the internode, suggesting that the thermal stability of the bamboo node is slightly higher than that in the internode.