Research on Fabrication and Physico-Chemical Properties of Polypropylene Fiber-Based Multilayer Materials

This study presents the fabrication and physicochemical characterization of polypropylene (PP) fiber-based multilayer materials using a gelatin hydrogel as a binder. A simple manual multilayer fabrication method was developed to assemble controlled nonwoven PP 8-, 16-, and 32-layer fibers into structured composites. The effect of fabrication parameters, particularly the volume of 5% gelatin solution, was optimized, with 150 µL per layer identified as suitable for achieving uniform adhesion and relatively thin structures. The 3 resulting PP multilayer materials were evaluated in terms of thickness distribution, wettability, and swelling behavior. Thickness measurements revealed non-linear scaling with layer number and noticeable structural non-uniformity between edge and central regions, attributed to binder migration and manual processing conditions. Surface wettability of the PP 16-layer fibers showed that untreated samples exhibited hydrophobic behavior (contact angle >90°), while cold plasma-treated samples displayed significantly improved wettability (contact angle <90°), indicating enhanced surface hydrophilicity due to plasma-induced functionalization. Swelling studies demonstrated rapid water uptake within the first hours, followed by stabilization. The overall swelling capacity of the materials remained high at 442,33% by stabilization, with minimal differences between untreated and plasma-treated samples after prolonged immersion, suggesting that plasma treatment did not compromise structural integrity, although a slight reduction in swelling was observed due to increased network stabilization. The study showed that the combination of PP fibers, gelatin binder, and cold plasma treatment enables the fabrication of multilayer materials with tunable physicochemical properties. These materials show promising potential for applications in filtration, biomedical systems, packaging, and absorbent materials.