Water Transport and Swelling Kinetics in NaOH-Saponified Chitosan-g-poly(acrylic acid) Superabsorbent Hydrogels: Model Discrimination and Phenomenological Interpretation

Dimas Prasetyo, Rahmayetty ., Jayanudin ., Endarto Yudo Wardhono, Widya Ernayati Kosimaningrum, Rudi Hartono

Abstract

This study reanalyzes the time-dependent swelling data of NaOH-saponified chitosan-graft-poly(acrylic acid) (Cs-g-PAA) superabsorbent hydrogels using complementary empirical, diffusional, and relaxation-based models. Five formulations differed in the degree of acrylic acid neutralization and nominal N,N′-methylenebisacrylamide (MBA) loading. The Schott, Peleg, Weibull, and Voigt models described the complete swelling-ratio profiles, whereas the Ritger–Peppas model was restricted to the initial fractional-uptake region, and the mixed diffusion–relaxation model provided a phenomenological partitioning of two kinetic contributions. Cs-g-PAA-4, prepared at 50% neutralization and with 0.015 g MBA, showed the highest swelling capacity. This result is associated with the lower nominal crosslinker loading but does not independently establish the crosslink density. Statistical indicators were interpreted only within comparable response-variable and data-range frameworks. The mixed model provided high fitting accuracy for most formulations, whereas the Weibull model adequately described the nonlinear swelling profile of Cs-g-PAA-4. These fits support, but do not directly prove, contributions from water transport and time-dependent network rearrangement. The conclusions are limited to the investigated Cs-g-PAA system in distilled water at 27 ± 1 °C.

Keywords

References

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DOI: 10.14416/j.asep.2026.09.013

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