Preparation and Characterization of PHBV/PLA/TPS Blends Containing Citric Acid-Modified Thermoplastic Starch

The aim of this study was to modify the structural, mechanical, thermal, rheological, and morphological properties of PHBV-based blends through the incorporation of PLA and citric acid-modified thermoplastic starch (TPS). Although PHBV is a biodegradable polymer with environmental advantages, its processing challenges and relatively low mechanical performance limit its practical applications, which can be addressed by blending it with PLA and TPS to tailor the properties of the resulting materials. TPS was prepared by plasticizing corn starch with glycerol and incorporating different concentrations of citric acid (0, 5, and 10 wt %). Subsequently, PHBV/PLA/TPS blends were obtained by extrusion and characterized by Fourier-transform infrared spectroscopy (FTIR), tensile testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), rheological measurements, and scanning electron microscopy (SEM). The results demonstrated that the addition of citric acid altered the morphology, mechanical properties, and thermal behavior of TPS, while its effects on the PHBV/PLA/TPS blends depended strongly on blend composition. Among the TPS formulations, T5 exhibited the highest tensile strength (9.6 MPa), whereas 40PH/30P/30T0 showed the highest tensile strength among the blends (18.7 MPa). The 40PH/40P/20T10 formulation exhibited the most homogeneous morphology and the highest thermal stability among the ternary blends, with a maximum degradation temperature of 295 °C. Overall, the incorporation of PLA and citric acid-modified TPS enabled the properties of PHBV-based blends to be tailored through changes in composition and TPS modification, demonstrating their potential for the development of biodegradable materials with improved and tunable performance.