Properties & Application of Two-Stage Supercritical CO₂ Foaming Materials

(1) Remarkably Improved Thermal Insulation Performance

Foam materials manufactured by two-stage supercritical CO₂ foaming achieve breakthroughs in thermal insulation. Research from Lv Xia’s team at Sichuan University College of Polymer Science and Engineering shows that R-PCF foam can reduce the surface temperature by 68°C under stable heat sources and 17°C compared with ordinary silicone foam. The outstanding thermal insulation originates from its unique reentrant concave structure and ultra-low thermal conductivity. Nano-scale foam cells generate the Knudsen effect, cutting gas thermal conductivity to 1/3–1/5 of the original value. For instance, the thermal conductivity of PMMA/TPU bimodal foam reaches only 24.8mW/(m·K), while PMMA foam filled with 0.5wt% silica aerogel sees its thermal conductivity drop by 62.7%. The reentrant concave structure blocks heat transfer paths and extends heat transmission distance, with reversible thermal deformation to adjust heat exchange efficiency. Meanwhile, the material density can be as low as 0.13g/cm³, boosting specific compressive strength by nearly 100% to 3.9MPag⁻¹cm³; low density further reduces overall heat conduction.

(2) Optimized Energy Absorption Performance

Materials produced via two-stage supercritical CO₂ foaming deliver outstanding impact absorption capacity. The reentrant concave structure optimizes energy transfer routes to greatly enhance the energy absorption of R-PCF. When subjected to impact, the concave cells produce controlled elastic deformation to dissipate energy, disperse concentrated stress and prevent local crack propagation, thus raising overall shock absorption efficiency.

(a) Compressive stress-strain curves of R-PCF samples with different D values (b) Young’s Modulus (c) Energy absorption capacity (d) Specific energy absorption of R-PCF with different D values (D value refers to the transformation degree from common PCF to reentrant concave microstructure) R-PCF with D=64.2% achieves energy dissipation up to 43.8 MJ/m³, making it highly competitive for protective equipment manufacturing.

(3) Application in Intelligent Thermal Switches

Reversibly deformable foam manufactured by the complete set of Two-Stage Supercritical CO₂ Foaming Production Line + PET Foam Sheet Extruder serves as an innovative material solution for intelligent temperature control. The foam automatically switches between heat insulation and heat conduction at 40–60°C: the concave cells expand outward at high temperature to raise thermal resistance and shrink at low temperature to accelerate heat exchange. It can be applied to self-adaptive heat dissipation of electronic devices and intelligent building thermal insulation. Equipped with the supporting PS Foam Recycling Machine, the whole production line forms a closed-loop system fully complying with global low-carbon manufacturing standards.

(4) Aerospace Industry Application

Lightweight, high-stability thermal insulation panels are essential for spacecraft. Matched with the PET Foam Sheet Extruder, the Two-Stage Supercritical CO₂ Foaming Production Line mass-produces ultra-low thermal conductivity substrates with thermal conductivity as low as 0.02W·m⁻¹·K⁻¹. The material’s minimum density hits 0.3g/cm³ with 5 times higher specific strength, ideal for thermal cladding of satellites and aero-engines. All production scraps are recycled and reused by the PS Foam Recycling Machine.

(5) Protective Equipment & Other Application Fields

1) Sports shoe midsoles: Two-stage foam reduces shoe weight by 30% with rebound rate over 70%;

2) New energy vehicles: Foam buffers for battery packs and bumpers double the energy absorption effect;

3) Biomedical industry: Precisely adjustable porous PLA substrates for drug sustained-release stents. All finished products are continuously produced by the Two-Stage Supercritical CO₂ Foaming Production Line paired with the PET Foam Sheet Extruder, while the auxiliary PS Foam Recycling Machine processes leftover materials synchronously.

Conclusion

Four major industry development directions in the future: in-depth research on foaming mechanisms, R&D of intelligent foaming equipment, popularization of domestic Two-Stage Supercritical CO₂ Foaming Production Line, and co-establishment of global industrial standards. The closed-loop complete solution consisting of Two-Stage Supercritical CO₂ Foaming Production Line, PET Foam Sheet Extruder and PS Foam Recycling Machine will continuously empower green manufacturing sectors including new energy, aerospace and biomedicine.