Impact of thermal treatment on the crystallization behavior and mechanical properties of semicrystalline PLGA

Poly (lactic-co-glycolic acid) (PLGA) copolymers with high glycolic acid (GA) content (PLGA80 with 80 mol% and PLGA90 with 90 mol%) are promising candidates for sustainable food packaging due to their degradability and favorable barrier properties. However, their processability is challenging and the relationship between thermal behavior, microstructure, and mechanical performance is poorly understood. This study investigates the influence of thermal processing parameters, specifically drying and thermopressing temperature, on the crystallization behavior and mechanical properties. The thermal processing behavior is first simulated by preheating the pellets at selected preheating temperatures (210–250 °C for PLGA90 and 190–200 °C for PLGA80) and analyzed using DSC, TGA, POM, and WAXS. Increasing preheating temperature reduces the degree of crystallinity from 23% to 2% for PLGA90 pellets and from 17% to 2% for PLGA80 pellets, and increases crystal size for both copolymers. At critical preheating temperatures (250 °C for PLGA90 and 200 °C for PLGA80), no clear crystallization peak was detected. Films produced under these different conditions exhibit predominantly amorphous structures, due to fast cooling rate and/or thermal degradation during thermopressing. For PLGA90, Young’s modulus decreases from 440 ± 40 MPa when processed at 210 °C to 230 ± 35 MPa when processed at 230 °C, while elongation at break increases from 190 ± 90 % to 740 ± 175%, respectively. Processing temperatures close to the melting point are therefore advantageous for maintaining a high Young’s modulus, whereas higher processing temperatures yield exceptional ductility, an important property for flexible film packaging. Depending on the targeted application, the processing temperature of PLGA films can thus be tailored to balance their stiffness and ductility. • Crystallization of PLGA pellets is governed by processing temperature. • Amorphous structure obtained by disruption of the melt memory. • Processing temperature tunes stiffness-ductility balance in PLGA. • Insights of PLGA thermal processing for packaging applications.