Methyl methacrylate (MMA), methyl acrylate (MA), and vinyl acetate (VAc) grafted pulps were beaten for six hours in water, ethanol and acetone, and the handsheets were made from them in the presence of water after removing the medium.
The influence of degree of grafting on the paper properties were discussed in connection with a microscopic observation of the beaten pulp.
1) Freeness of the beaten grafted pulp increases irrespective of beaten state.
2) Tensile strength of the paper made from the water beaten grafted pulp decreases with increasing degree of grafting, but that of the acetone beaten MA and VAc grafted pulp increases, that of the acetone beaten MMA grafted pulp shows only a relatively slight decrease. In the case of beating in ethanol, the strength of the paper from VAc grafted pulp increases slightly, while that of other pulps decreases.
3) Fold endurance of the paper made from the water beaten grafted pulp decreases remarkably with increasing degree of grafting. In the case of beating in ethanol and acetone, the strength of the paper from the acetone beaten MA and VAc grafted pulp increases, but that of others is almost unchanged.
4) Air resistance of the paper made from the water beaten grafted pulp decreases, but in the case of beating MA grafted pulp in acetone and VAc grafted pulp in ethanol or acetone increases remarkably.
5) A linear relationship is found between water retention value of beaten pulp and tensile strength of the paper, between solid fraction and logarithm of air resistance of the paper irrespective of beating medium and kinds of the grafted pulp.
The fact that grafted pulps show the different beating states (see photomicrographs) is due to the differences of the degree of affinity of the grafted polymer for the medium and the degree of grafting.
The reason why the paper made from the water beaten original pulp gives higher tensile strength than the highest value of the paper made from the acetone beaten grafted pulp although the solid fraction and the wax surface strength of the former is lower than those of the latter seems to be mainly due to the abundance of short fiber fraction owing to the overbeating in the latter.
Tensile strength and thickness of the paper using acetone in sheet preparation are also compared with those of the paper using water and lower strength are obtained in the case of using acetone.