Lightweight polyethylene terephthalate bead foams with good interfacial adhesion and thermal insulation performance fabricated by supercritical carbon dioxide secondary foaming strategy

This paper reported the novel supercritical carbon dioxide (scCO₂) secondary foaming and molding strategy to prepare the thermal-insulation polyethylene terephthalate (PET) bead foam part with good interfacial adhesion and high expansion ratio. The incorporation of porous structure could effectively enhance the blowing agent solubility and fabricate the system viscosity difference, which contributed to the expansion and further welding of the expanded PET beads. Under the optimum foaming conditions, PET bead foam parts with excellent comprehensive performance were successfully prepared by molding method in the confined space via scCO₂ secondary foaming, and the corresponding welding mechanism of PET beads was further investigated. The obtained foam parts possessed good tensile and compressive properties, reaching 1.03 and 1.27 MPa (at 20% strain) respectively. Besides, the foam part exhibited the low thermal conductivity of 0.060 Wm⁻¹ K⁻¹, which confirmed the improvement of thermal insulation performance owing to the high expansion ratio. © 2023 Wiley Periodicals LLC.