Microstructural study of carbonized wood after cell wall sectioning

Wooden blocks of Japanese cedar (Cryptomeria japonica) were carbonized at 700 and 1,800 degrees C. The microstructure was analyzed by transmission electron microscopy (TEM) and mu-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 degrees C showed ordered regions in the surface layer of cell walls. This result was supported by polarized mu-Raman analysis. It may be caused by the deposition of carbon compounds volatilized from the cell walls during pulse current heating.