The development of biocomposites using renewable resources is a cost-effective and long-term solution to environmental and resource issues. Hydrogels [Poly Sodium Acrylate (PSA)] were created by variable percentages of crosslinker concentration, and banana–cellulose microfibril (CMF) was used as a filler in this study for better reinforcement. When the concentration of crosslinker is increased, the number of covalent crosslinks increases, limiting the movement of water molecules and lowering the diffusion coefficient, equilibrium water content, the initial rate of swelling, and the theoretical equilibrium swelling ratio. The swelling behaviour of reinforced PSA with high concentrations of CMF was unexpected; the hydrophilic OH groups of CMF increase the diffusion of water molecules from the swelling medium to inside the PSA, allowing for better mechanical behaviour of gels without sacrificing the swelling response. The swelling behaviour and swelling exponent of a hydrogel were determined at various temperatures, pH levels, and physiological fluid models. The swelling exponent's maximum value was discovered to be 0.5, which suggests that the hydrogel's water diffusion was non-Fickian in nature. The swelling ratio was found to rise with rising temperature and to have a lower value than that at room temperature. It was also proven that elevating the pH of the medium from 1 to 7 improved the PSA/CMF hydrogels' swelling response. The swelling behaviour of PSA/CMF hydrogels was also investigated as the concentration of CMF rose from 0.2 to 1%. The equilibrium water content, swelling kinetics, and water transport mechanisms were all investigated. The Flory–Rehner equation was applied to determine crosslinking density, polymer mesh size, and molecular weight between crosslinks.

Preparation and evaluation of physicochemical studies of novel natural cellulose microfibril (CMF) reinforced poly (sodium acrylate) hydrogel
    Abstract
        Graphical abstract
    1 Introduction
    2 Materials and methods
        2.1 Chemicals
        2.2 Preparation of materials
            2.2.1 Preparation of CMF
            2.2.2 Preparation of hydrogel
            2.2.3 Physiological fluids’ preparation
    3 Methods: physicochemical characterisation
        3.1 Swelling measurements
            3.1.1 Swelling and diffusion behaviour
        3.2 Network parameters of hydrogel
            3.2.1 Determination of molecular weight between the crosslinks, 
            3.2.2 Determination of mesh size, ξ and crosslinking density, 
    4 Results and discussion
        4.1 Effect of crosslinker concentration on the swelling response of PSA hydrogels
        4.2 Effect of CMF concentration on the swelling ratio of hydrogels
        4.3 Effect of pH on the swelling response of PSACMF hydrogel
        4.4 Effect of physiological fluids on the swelling ratio of PSACMF hydrogels
        4.5 Network parameters of PSACMF hydrogels
    5 Conclusion
    Acknowledgements 
    References

• Nithya Ramasamy(Department of Plastic Technology, Central Institute of Petrochemicals Engineering and Technology (CIPET), Institute of Petrochemicals Technology (IPT), Chennai, Tamil Nadu, India, Department of Chemical Engineering, Anna University, Chennai, Tamil Nadu, India)
• Anbudayanidhi Sivalingam(Department of Plastics Technology, Central Institute of Petrochemicals Engineering and Technology (CIPET), Institute of Petrochemicals Technology (IPT), Chennai, Tamil Nadu, India)
• Shanmuga Sundar Saravanabhavan(Department of Biotechnology, Aarupadai Veedu Institute of Technology, Vinayaka Mission’s Research Foundation (Deemed to be University), Paiyanoor, Tamil Nadu, India)
• Kavitha Nagarasampatti Palani(Department of Chemical Engineering, Sri Venkateswara College of Engineering, Chennai, Tamil Nadu, India)
• Balasubramanian Natesan(Centre for Energy Storage Technologies, Anna University, Chennai, India, Department of Chemical Engineering, Anna University, Chennai, Tamil Nadu, India)