EFFECT OF GRINDING ON BOUND WATER IN CELL ULOSIC MATERIALS

From low-temperature differential scanning calorimetric measurements o f water in cotton cellulose powder (Whatman CF11 cellulose powder), wo od meals, and wood-related materials, three kinds of water, nonfreezin g water, freezing bound water, and free water were estimated. Two kind s of freezing bound water were observed in all of the samples investig ated. The amounts of nonfreezing water of CF11 and xylan were 12.7% an d 43.6%, respectively, whereas the values of akamatsu (Pinus densiflor a S. and Z.) and buna (Fagus crenata Bl.) wood meals and thermomechani cal pulp (TMP) were nearly the same, being 28.2-28.3%. When CF11 was g round by a vibratory mill with a special-rod (VSRM) or balls (VBM) as a grinding medium, the amount of nonfreezing water of CF11 increased with increases of grinding time and was greater for the VSRM than for the VBM. The amount of freezing bound water of CF11 decreased rapidly in the early stage of grinding, and did not recover to the original l evel. There was a good correlation between the amount of nonfreezing w ater, crystallinity index, and extent of hydrolysis, regardless of the grinding medium. On the other hand, the degree of increase in the amo unt of nonfreezing water of TMP during grinding was much smaller than that of CF11. This reason is not clear at present.