UTILIZATION OF CELLULOSIC WASTES .8. ELECTRON-SPIN-RESONANCE STUDIES OF THE GRINDING OF CELLULOSIC MATERIALS

The grinding efficiencies of a special-rod (VSRM) and balls (VBM) as grinding media, for enzymatic hydrolyses of thermomechanical pulp (TMP ) and Whatman CF11 cellulose powder (CF11), were first compared by usi ng one kind of vibratory mill. The grinding efficiency of the VSRM was about three times that of the VBM , indicating that kinds of grindin g media greatly affect the grinding efficiency of a vibratory mill. Th en the effects of grinding media on free-radical concentrations of gro und CF11 and TMP were investigated, and the relationships between the free-radical concentrations and enzymatic hydrolyses are discussed. Th e free-radical concentrations of CF11 and TMP ground in the VSRM incre ased more rapidly than those in the VBM until a 10-min grinding. How ever, after that, the radical concentration in the VSRM decreased with increasing grinding time, whereas that in the VBM increased continu ously and became greater than that in the VSRM at a 20-min grinding. T hese results suggest that the time course of free-radical concentratio n with grinding may depend on the difference in the grinding mechanism s between the special-rod and the balls and the softening of the wood components. The facts that the extents of hydrolyses of CF11 and TMP w ere slightly greater with the VSRM than with the VBM at the same free -radical concentration, suggest that other factors as well as the numb er of scissions of their intramolecular covalent bonds affect the hydr olyses of ground CF11 and TMP.