Fabrication of Ultralightweight Poly(lactic acid)/Pentaerythritol/Carbon Nanotube Composite Foams with Enhanced Heat Insulation and Compressive Properties by Supercritical CO2

Uniform dispersion of the carbon nanotube (CNT) within the polymer matrix is crucial for maximizing its reinforcement effects. To achieve this, pentaerythritol (PENTA) and CNTs were simultaneously introduced into the polylactic acid (PLA) matrix in this work. PENTA crystallizes prior to PLA, acting as a heterogeneous nucleating agent that promotes the formation of matrix microcrystals, which increases the migration resistance of the CNT, effectively suppressing CNT agglomeration and enhancing CNT dispersion uniformity. The uniform dispersion of CNTs induced by PENTA significantly enhanced the melt strength and foaming performance of PLA. Meanwhile, the introduction of CNTs reduced the thermal radiation and enhanced the mechanical properties. By leveraging these synergistic effects, ultralight PLA/PENTA/CNT foams were fabricated via supercritical CO₂ (scCO₂) foaming, which exhibited excellent thermal insulation and mechanical properties, with an expansion ratio up to 54, a thermal conductivity as low as 29.22 mW·m^–1·K^–1, and a specific compressive modulus as high as 102.10 MPa·g^–1·cm³. Therefore, this work provides a green and sustainable method for the preparation of PLA foam with exceptional heat insulation and compression performance.