Recycling Polyethylene into High‐Value Porous Carbon Composites for Microwave Absorption

Abstract

The recycling of solid plastic waste has been a major challenge to the sustainable development of today's society. Herein, one of the commonly wasted plastic raw materials, linear low‐density polyethylene (LLDPE), is used as the carbon source to explore high‐value porous carbon composites for microwave absorption applications. The carbon composites are simply obtained through the delicate carbonization of LLDPE, followed by in situ introducing Ni nanoparticles (NPs) into the carbon monolith. The porous carbon composites show a minimum reflection loss (RLmin) value of −52.2 dB at 1.65 mm, which demonstrates excellent microwave absorption properties of the wasted plastic‐derived carbon materials. In addition, the anticorrosion performance of the carbon composites is evaluated by electrochemical technique. Above all, the current study provides a new idea and simple strategy for processing wasted plastics to high‐value porous carbon materials.

Urea-Assisted Green Synthesis of CeO2 Nanoparticles/Porous Carbon Composites for Microwave Absorption

“…First, as shown in Figure a, the distinct three-dimensional porous structure and multiple reflections and scattering at interfaces in the samples are analyzed. The structure in discussion works to increase the attenuation of incident EMW by extending their routes of propagation . Second, the Maxwell–Garnett model is taken into account, which shows that the porous structure of porous carbon efficiently lowers the composite material’s dielectric constant, increasing the materials’ impedance matching capabilities .…”

“…The structure in discussion works to increase the attenuation of incident EMW by extending their routes of propagation. 68 Second, the Maxwell−Garnett model is taken into account, which shows that the porous structure of porous carbon efficiently lowers the composite material's dielectric constant, increasing the materials' impedance matching capabilities. 69 11b), where R is the resistance of CeO 2 and N-doped porous carbon, r is the resistance due to the dipole orientation in the heterostructure, and C is the equivalent capacitance of the heterostructure.…”

A Novel Low-Density-Biomass-Carbon Composite Coated with Carpet-like and Dandelion-Shaped Rare-Earth-Doped Cobalt Ferrite for Enhanced Microwave Absorption

“…A larger absolute R L value signifies less reflection and a greater proportion of the wave penetrating into the absorber, indicating superior absorption performance [ 15 , 42 ]. The R L value could be accurately determined by application of a specified mathematical formulation, grounded in the principles of transmission line theory [ 43 ]: R L (dB) = 20 log|( Z 0 − Z in )/( Z 0 + Z in )|, where Z 0 represents the fundamental impedance for surrounding vacuum or air, whereas Z in signifies the resistive property encountered by an incoming wave at the interface of the microwave-absorption material. Typically, the input impedance ( Z in ) of the microwave-absorption material can be derived using the mathematical expression outlined below: Z in = Z 0 ( μ r / ε r ) 1/2 tanh[ j ( ε r μ r ) 1/2 (2 πdf/c )] where the thickness of the absorption layer, denoted by d , along with the velocity of EW in a vacuum, c , and the frequency of the incoming EW, f , play vital roles in determining the performance of the absorber.…”

“…A larger absolute R L value signifies less reflection and a greater proportion of the wave penetrating into the absorber, indicating superior absorption performance [15,42]. The R L value could be accurately determined by application of a specified mathematical formulation, grounded in the principles of transmission line theory [43]:…”