An investigation of mercerization in decayed oak wood by a white rot fungus (Lentinula edodes)

The crystal transformation of cellulose I to cellulose II during alkali swelling was investigated in decayed oak wood that was used for shiitake mushroom cultivation and the results were compared with those of sound wood using X-ray diffraction analysis and ultraviolet microscopy. During mercerization, the sapwood cellulose of decayed wood was easily transformed into Na-cellulose I and then Na-cellulose I was easily converted into cellulose II after washing and drying. The sapwood cellulose of sound wood was converted more slowly to Na-cellulose I and very little Na-cellulose was converted to cellulose II. Na-cellulose I of sound wood can be reconverted to cellulose I during washing and drying. Therefore, it could be concluded that lignin prevented the alkali swelling of wood cellulose and the transformation from cellulose I to cellulose II. The decay of crystalline cellulose might cause an increase in the susceptibility of alkali swelling, so that the degree of mercerization may be also affected.