Sustainable Porcine Plasma/Carboxymethyl Chitosan Bioplastics: Tunable Porosity for High-Performance Absorbents

Abstract This study reports the development of injection-moulded bioplastics based on porcine plasma proteins (PPP) blended with carboxymethyl chitosan (CMCH), as sustainable absorbent materials for hygienic-sanitary applications as alternative to conventional polyurethane foams. Glycerol (Gly) was used as a plasticizer, while sodium carbonate (SC) was employed to induce porosity, and genipin (G) as a natural crosslinking agent. The materials were characterized by FTIR, XPS, thermogravimetric analysis, dynamic mechanical analysis, tensile testing, and scanning electron microscopy. The liquid absorption assays included water uptake capacity (WUC), free swell capacity (FSC), centrifuge retention capacity (CRC), absorption under load (AUL), and rewet performance. SC incorporation increased porosity and free swelling, so that PPP-CMCH/Gly_SC reached 3600 WUC%. Conversely, G-crosslinking reduced soluble matter loss and enhanced stiffness and AUL, with PPP-CMCH/Gly/G_SC formulation achieved a superior balance reaching an AUL of 5.97 g/g and rewet values as low as 0.77 g. This bioplastic reached FSC, CRC and AUL values of about 52%, 22% and 100% with respect to a commercial PU foam. Overall, the combined porosity-inducing and crosslinking strategy enabled a balance between absorbency and mechanical integrity.