Fabrication and characterization of PVA–cellulose and PVA–clay composites: structural, mechanical, and in vitro degradation studies

This study investigates the structural, mechanical, and degradation properties of PVA composites (0.15–0.25 mm) reinforced with cellulose and kaolin clay, fabricated via solvent casting. The composites (1–5 wt.% filler) were characterized using XRD, FTIR, inverted microscopy, colorimetry, hardness testing, and tensile analysis. XRD revealed cellulose preserved PVA’s semi-crystalline structure, while clay induced intercalation, expanding interlayer spacing. FTIR confirmed hydrogen bonding between PVA and both fillers, with cellulose enhancing hydrophilicity. Microscopy showed cellulose formed fibrous networks, whereas clay created platelet-rich domains. Cellulose composites exhibited higher optical scattering (55% increase in violet light absorption at 5% loading) compared to clay (15%), correlating with surface roughness. Mechanical testing demonstrated clay’s superior reinforcement, increasing tensile strength by 24% (25.5 MPa) but reducing ductility (105% elongation), while cellulose balanced strength (22 MPa) and flexibility (155% elongation). In vitro degradation in PBS revealed cellulose accelerated weight loss (5.3% over 15 days) due to hydrophilic networks, while clay impeded degradation (3.5%) via tortuous pathways. Thermal analysis highlighted clay’s stabilizing effect, delaying decomposition by 50 °C versue pure PVA. The results indicate that cellulose-reinforced composites are promising for biomedical applications requiring controlled degradability, whereas clay-reinforced composites exhibit superior durability and moisture resistance, making them suitable for packaging. These findings highlight the trade-offs associated with filler selection in tailoring PVA properties for specific end uses.