Test Method for Rate of Water Absorption

Depending on the type of superabsorbent polymers, measurement of the rate of water absorption is possible using the tea bag method and the DW method. 

Vortex method A specified amount of solution in a beaker is stirred while a specified amount of superabsorbent polymer is added. The time for the liquid surface to become flat or for the stirrer chip to hide beneath the liquid is measured. 

However, when the rate of water absorption is very fast because of a certain type and particle size, such a measurement is very difficult. Therefore, the use of a method to determine the force to eliminate fluidity (gelation force) is regarded as a reasonable approach. Due to its ease of use, the vortex method (see Table 2) is selected. 

In a manner similar to the method described in the water uptake information four types of superabsorbent polymers were used as common samples and eight organizations determined the rate of water absorption by varying conditions that included particle size, the amount of sample, the method of sample addition to the solution, stirring condition, method to identify the end point, two types of solution, the amount of solution, measurement temperature, and the number of measurements. Based on the results and their analysis, the method for measuring the rate of water absorption for superabsorbent polymers is proposed as follows. 

Testing Method for the Rate of Water Absorption of Superabsorbent Polymers (proposal, only the main text is extracted) 

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