Testing of Superabsorbent Polymers

Applications / Superabsorbent Polymers

Superabsorbent materials such as SAPs have the capacity to absorb extremely large amounts of liquid compared to their mass. This class of materials was developed in the 1960s mainly to retain water for agricultural applications. Since then, superabsorbent materials have been used in various applications and industries such us: wound dressing, surgical pads, diapers and adult diapers, filtration, release of insecticides, potting soil, flood control and prevention, stabilization of waste. Superabsorbents are made of dried polymers that have the capacity to rapidly absorb water or saline solutions and to retain the absorbed liquid. Because mastering this functionality is critical for superabsorbents, it is important in R&D and QC to precisely measure how a specific SAP absorbs a given solution.

ElastoSens™ Bio measures in real time how superabsorbents absorb a liquid solution by measuring the elastic modulus of the forming gel during absorption. The instrument measures the exact time when absorption starts, the speed of absorption (speed of swelling) as well as the final gel elastic modulus. ElastoSens™ Bio can also characterize how superabsorbents react to multiple/sequential intakes and how porosity evolves at low absorption rates.

In this example, the effect of the water-to-superabsorbent ratio on the kinetics of absorption was studied using the ElastoSens™ Bio. The water-to-powder ratio was varied as follows: 100, 150, 200, 250, 300, 350 and 400 g/g. As it can be seen, the absorption kinetics is strongly affected by the water-to-powder ratio. The absorption was initiated more rapidly when the ratio was low. It also clearly appears that the stiffness of the resulting gel was inversely proportional to the water-to-powder ratio. ElastoSens™ Bio can serve to study how chemical and physical conditions affect the absorption of solutions by a superabsorbent polymer (SAP).

The ElastoSens™ Bio also proved to be useful to study the incremental absorption of a solution. It can also be used to study, in vitro, the absorption of physiological liquids and to simulate real life conditions.

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Testing the Swelling of Superabsorbent Polymers (SAP) and Gel Formation using ElastoSens™ Bio

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January 30, 2021