ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 9, Number 1
JKCSEZ 9(1)
February 20, 1965 

The time-lag-effect of alkali salts on the gelation of sodium alginate-CaSO4·1 /2H2O is compared with Miyake's data, and then the formation rate of the elastics measured by the continuous method (an improved Schwedoff's method) and the change of rigidity with metallic oxides are studied as follows: (1) The gelation processes of sodium alginate and CaSO4·1/2H2O-aqueous sol are studied by measuring, continuously the increases of tensions ofsamples. (2) The time-lag-effect of Na3PO4 on the formation rate of the elastic gel is larger than that of Na2CO3, but the difference between the effects of the two alkali salts on the rate is found not so greater than predicted in Miyake's data. (3) Any regularities of the effect on the rate by metallic oxides are not observed. The increasing effects of the rates of SiO2 and MgO are relatively large, and that of ZnO is relatively small. However, Al2O3, Sb2O3 and TiO2show some decreasing effects. As a result it is noted that the regularities do not depend on the effect of oxide species and their amounts. (4) It is not found proportionality between the rigidity and the gelation rate. However, the increasing effect of the rigidity with the addition of metallic oxides can be observed. The rigidity increasing rate of MgO is the largest of them.