Compatibilization Strategies for PLA/PCL Blends: Tuning Thermal, Mechanical, and Biodegradation Properties via Functionalized PCL Derivatives

The limited miscibility of poly (lactic acid) (PLA) and polycaprolactone (PCL) restricts their broader use despite their biodegradability and mechanical performance. This study prepared PLA blends with functionalized PCL derivatives-PCL-grafted maleic anhydride (PCL-g-MA) and PCL-grafted glycidyl methacrylate (PCL-g-GMA) through melt blending, aiming to enhance interfacial adhesion and optimize performance. Thermogravimetric analysis (TGA) revealed increased thermal stability in the blends, with a degradation onset temperature (Tonset) rising from 290°C in neat PLA to 310°C in PLA/PCL-g-GMA blends. Mechanical testing showed that tensile strength decreased from 52.4 MPa to 39.2 MPa as PCL-g-GMA content increased from 10 to 40 wt%, while impact strength improved from 3.5 kJ/m2 to 5.5 kJ/m2. Differential scanning calorimetry (DSC) confirmed a reduction in glass transition temperature (Tg) from −6°C to −12°C with increasing PCL-g-GMA content, indicating a plasticizing effect. Soil burial biodegradation tests showed that weight loss increased from 2.1% to 15.5% over 45 days as the PCL-g-GMA content increased. SEM images revealed finer dispersion and improved interfacial adhesion in PCL-g-GMA blends compared to PCL-g-MA. These results demonstrate that reactive compatibilization with PCL-g-GMA and PCL-g-MA improves phase compatibility, thermal stability, toughness, and biodegradability of PLA/PCL blends, making them promising candidates for sustainable packaging and biomedical applications.