Polyacrylic Acid Superabsorbent Polymer with Swelling Modulus Control

The patent removes the foaming agent from the polymerization system entirely, replacing it with a different cross-linking approach that does not rely on gas bubble formation. This extraction of the problematic component eliminates the degradation of physical properties while maintaining porous structure through alternative means.

The patent changes the cross-linking density parameter to an optimal range (0.5-5 mmol/kg based on acrylic acid content) that balances permeability and centrifuge retention capacity without requiring foaming agents. This parameter optimization allows the polymer to achieve both high surface area and maintained physical properties.

The patent identifies and implements an optimal cross-linking density range (0.5-5 mmol/kg based on acrylic acid content) that simultaneously achieves high permeability and maintains centrifuge retention capacity. This precise parameter control resolves the trade-off by finding the sweet spot where the cross-linked structure provides sufficient permeability without becoming so dense as to block moisture absorption.

The patent applies partial cross-linking rather than extensive cross-linking, using a controlled amount of cross-linking agent that provides just enough structural integrity and permeability enhancement without creating excessive cross-linking that would block moisture pathways. This partial action approach optimizes both permeability and absorption capacity.