Highly Compressible Polymer Composite Foams with Thermal Heating-Boosted Electromagnetic Wave Absorption Abilities

Area of Science:

• Materials Science
• Nanotechnology
• Electromagnetism

Background:

• Polymer composite foams are promising for electromagnetic (EM) energy attenuation.
• Improving EM attenuation in foams faces challenges.
• Microcellular structures can enhance foam properties.

Purpose of the Study:

• To fabricate compressible thermoplastic urethane (TPU)/carbon nanotube (CNT) composite foams using microcellular injection molding.
• To investigate the effect of CNT content on conductivity and EM attenuation.
• To explore stimulation-dependent EM attenuation properties.

Main Methods:

• Microcellular injection molding of TPU/CNT composite foams.
• Characterization of conductivity and EM attenuation properties.
• Evaluation of EM attenuation under thermal heating and cyclic compression.

Main Results:

• Foamed composites exhibited higher conductivity and EM attenuation than unfoamed ones.
• TPU/CNT foam with 4 wt% CNTs (F(4)) showed optimal reflection loss (RL) of -30.4 dB.
• Stimulation (thermal/compression) further increased EM attenuation, with a record RL of -51.8 dB for a 1.3 mm thick F(4) foam at 333 K.

Conclusions:

• Microcellular structure and increased CNT content enhance EM attenuation in TPU foams.
• Stimulation-dependent EM attenuation is achievable through CNT movement.
• These composite foams are potential candidates for multifunctional materials with tunable EM properties.