Multiscale-void-containing low-density polyethylene/waste plastic porous carbon composites with electromagnetic shielding interference and thermal management capabilities†

The problems of inadequate waste plastic (WP) treatment methods, serious electromagnetic hazards, and the difficulty of metal-based electromagnetic shielding interference (EMI) materials to meet the demand have become increasingly prominent. This work uses WP and melamine as raw materials, combined with CaCO₃ in WP as a self-sacrificial template agent, to synthesize nitrogen-doped waste plastic porous carbon (WPPC) by sintering. N doping endows WPPC-3 with high hydrophobicity, high electrical conductivity, and high EMI efficiency (20.5 dB in the Ku-band). First-principles calculations also demonstrate that WPPC-3 has a much better conductive structure than WPPC-0. The low-density polyethylene (LDPE)/template agent (TEM)-40 and LDPE/graphite tailing (GT)-70 have high toughness and high EMI efficiency, respectively. The EMI SE_T of the multi-scale pore structure functional composite material modified with WPPC (MSP-WPPC) increases by 670.93% in the Ku-band, compared with LDPE/GT-40. The synergistic effect of the matrix pore and WPPC mesoporous structure greatly improves the multiple reflection and absorption loss of MSP-WPPC. Polyethylene glycol (PEG) effectively fills the pore space within the structure of MSP-WPPC, thereby conferring upon MSP-WPPC/PEG the remarkable capacity for thermal management. The benefits of multi-solid waste utilization, low cost, and wide frequency EMI make MSP-WPPC/PEG well-suited for the military, construction, and communication industries. It will be a creative solution to the above problems.