Innovative Enhancement of Mechanical and Thermal Properties of Polylactic Acid Foam by Adjusting Crystallization

Polylactic acid (PLA) foam, known for its biodegradability and biocompatibility, faces limitations due to poor melt viscosity and low crystallinity. To address these issues, this research utilizes ethylene‐glycidyl methacrylate copolymer as a chain extender (CE) to enhance PLA and incorporates the nucleating agent diphenylhydrazide sebacic acid (ST‐NAB3) to adjust its crystallization characteristics. The CEPLA/ST‐NAB3 material is developed and foamed using supercritical CO 2 and an intermittent method. Observations by polarizing microscope and differential scanning calorimeter show increases in both the crystallization rate and crystallinity of the CEPLA/ST‐NAB3 sample. When the ST‐NAB3 content is 0.4 wt%, a transformation from spherulite to string crystal morphology occurs. Rheological tests show higher melt strength compared with pure PLA, thereby improving its foaming behavior. When the foaming temperature is 108 °C, the PLA foam with 0.4 wt% ST‐NAB3 has the smallest cell size and the highest cell density, which are 55.38 μm and 3.95 × 10 6 cells cm −3 , respectively. Following annealing treatment, the compressive strength of the CEPLA/ST‐NAB3 foam containing 0.4 wt% ST‐NAB3 increases to 5.35 MPa, while its Vicat softening temperature rises to 87.4 °C. This study offers an effective approach to enhance the performance of PLA foams, expanding their potential applications in various industries.