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

Abstract

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.