One‐Step Fabrication of Lightweight PLA Foam Boards With Enhanced Compressive Performance and Thermal Insulation

ABSTRACT An integrated foaming and molding strategy was developed to produce lightweight poly(lactic acid) (PLA) foam boards from pellets modified with dicumyl peroxide and trimethylolpropane triacrylate (TMPTA) using supercritical CO 2 . Torque, spectroscopic, gel content and rheological analyses provided indirect evidence consistent with crosslinked structure formation, while increased complex viscosity and elastic response suggested improved melt strength. Concurrent pellet expansion and interparticle bonding enabled board formation within a single foaming cycle, eliminating separate secondary molding. At 135°C and 15 MPa, PLAD T0.75 achieved the highest volumetric expansion ratio of 32.80 and the lowest density of 0.038 g cm −3 . PLAD T0.5 exhibited balanced cellular morphology and functional performance, with an expansion ratio of 30.76, a density of 0.041 g cm −3 , a compressive stress of 2.51 MPa at 80% strain and a thermal conductivity of 0.037 W m −1 K −1 . It also exhibited the lowest compressive creep strain among all samples at 100°C and 0.2 MPa after 1 h. Increasing TMPTA to 1 wt% caused cell coarsening and reduced overall performance. These findings demonstrate the importance of balancing the extent of reactive modification with cellular structure. They provide a practical, simplified route to PLA foam boards combining low density, compressive load‐bearing capacity and thermal insulation.