The Morphological, Thermal, and Mechanical Properties of Glass Ionomer Modified Polylactic Acid Polymer

This study evaluated the morphological, thermal, and mechanical behavior of polylactic acid (PLA) composites modified with conventional self-cured glass-ionomer cement (GIC) (Fuji VII; GC Corporation, Japan)-fully set and ground into powder-or sodium fluoride (NaF; Merck, USA) under simulated oral hydrolytic degradation. PLA based films containing 0-20 wt% fillers were produced by solvent casting, immersed in phosphate-buffered saline (PBS) at 37°C for up to 28 days, and characterized using scanning electron microscopy, differential scanning calorimetry, and tensile testing. Surface analysis showed that GIC filled PLA maintained a slight roughness and intact morphology with minimal void formation over time, whereas high NaF loading promoted pronounced surface porosity due to filler dissolution and enhanced water ingress. Thermal analysis indicated small increases in glass transition temperature after filler addition and aging, while cold crystallization and melting enthalpies were strongly dependent on filler type and concentration, with 5 wt% GIC supporting high crystallinity and higher loadings progressively suppressing crystal development during aging. Mechanically, pure PLA displayed an initial increase in tensile strength followed by marked deterioration, NaF filled films exhibited concentration dependent weakening particularly at 20 wt%, and PLA containing 5 wt% GIC showed the most stable tensile strength response over 28 days. Overall, PLA containing a low content of GIC, particularly 5 wt%, provides a favorable balance of structural stability and controlled crystallization. These findings warrant further preclinical investigation as a candidate fluoride-releasing and rechargeable material for dental applications. This study does not establish clinical suitability.