Studies on The Measurement Method of Porosity of Paper

The measurement methods of paper by the porosity testers of six kinds, Gurley densometer, Emiel Greiner porositymeter, Schopper air permeability meter, Emanueli porositymeter, Oken type denso-aspero meter and smoother, were examined, and further the relationships between these testers were theoretically and experimentally obtained.(1) In the relation between the Gurley densometer (G) and the Emiel Greiner porositymeter (E), the theoretical formulas agreed well with the experimental values. But, in the range of low air resistance, the experimental values by the Emiel Greiner porositymeter were smaller than the theoretical ones, whereas in the range of high air resistance, that relation was reverse.The relationship between two testers was shown by the following theoretical formulas.Ve=83046.6/0.803tG+513.34 … (1) VE= (979+0.675Ve) /1033 Ve … (2)were Ve and VE in cc/5mintG in sec/100cc (2) In the relation between the Schopper air permeability meter (S) and the Gurley densometer or the Emiel Greiner porositymeter, the theoretical formulas agreed very well with the experimental values.Especially, the theoretical formula of relation between the Schopper and the Gurley was in better agreement with the experimental values than that relation between the Emiel Greiner and the Gurley.The relationship between the Schopper and the Gurley was shown by the following theoretical formula.tG=24096.38/Vs … (3)where tG in sec/100ccVs in cc/5in(3) In the relation between the Emanueli porositymeter (M) and the Gurley densometer, the theoretical formula also agreed well with the experimental values, and this formula was as followsAM=43.478×tG/d … (4) ortG=523.023×P1/P2… (5)where AM in a unit of Emanuelid is thickness in cmtG in sec/100ccP1 or P2 is a differernt pressure (4) The Oken type denso-asperometer (O) and the Smoother (SM) have close relation with usual tester as the Gurley densometer etc.These testers were suitable for a manufacturing process test of high air resistance paper because these testers have superior accuracy and especially made the rapid test possible.The relationship between the Gurley and the Smoother was shown by follows experimental formulas;in the case which standard head was used, log HSM=-1.146log tG+5.122…(6) in the case which cramp type head was used, log Hsm=-0.638 log tG+4.247… (7)The relationship between the Gurley densometer and the Oken type denso-aspero meter was shown by the following experimental formula, log T0=0.965 log tG+0.0818… (8)