Microstructural study of carbonized wood after cell wall sectioning

Wooden blocks of Japanese cedar (Cryptomeria japonica) were carbonized at 700 and 1,800 °C. The microstructure was analyzed by transmission electron microscopy (TEM) and μ-Raman spectroscopy of the inner planes of wood cell walls. The predominant structure was of a turbostratic nature and no heterogeneity was observed originating from the original cell walls. TEM observations of samples carbonized at 1,800 °C showed ordered regions in the surface layer of cell walls. This result was supported by polarized μ-Raman analysis. It may be caused by the deposition of carbon compounds volatilized from the cell walls during pulse current heating.