Search

As a common environmental pollutant, microwave can cause great harms to human health. The development of high-performance microwave absorber with lightweight is indeed necessary. Herein, "rattan-like" graphene-based composite aerogels, having macroscopic pores surrounded by plenty of small pores, were designed and fabricated via an in-situ foaming then carbonized approach. Firstly, graphene oxide (GO), nanocellulose and ferrous ions were integrated into an aerogel with uniform large pores via a freeze-casting method. Then, the aerogel was immersed into a H 2 O 2 solution, during which bubble clusters generated in situ. These bubbles were driven into the stacked GO sheets and formed small pores. With the increase of the H 2 O 2 concentration from 0.5 to 10 wt%, the count percentage of the small pores in the aerogel increased from 81.5 to 95.2%. After the final carbonization, the graphene sheets were dually interconnected with magnetic nanoparticles and carbonized nanocellulose. The unique porous structure and dual-connected networks endowed the aerogel with enhanced conductive loss and optimized impedance matching capacity, and thus an excellent microwave absorption performance, whose maximum reflection loss achieves −68.5 dB. Further, the aerogel also exhibited superior sound absorption performance (noise reduction coefficient up to 0.91 in 1000–6300 Hz), and good mechanical stability. [Display omitted] • An in-situ foaming then carbonized process was developed to controllably fabricate "rattan-like" RGO-based aerogel. • By increasing C H2O2 from 0.5 to 10 wt%, the count percentage of small pores in aerogel increased from 81.5 to 95.2%. • "Rattan-like" structure and dual-connected networks endowed the aerogel with excellent microwave absorption capacity. • The aerogel also exhibited superior sound absorption capacity and good mechanical stability. [ABSTRACT FROM AUTHOR]

The widespread usage of carbon fiber-reinforced polymer composites imposes serious challenges in disposing of end-of-life and wasted products. Pyrolysis recycling has become an efficient strategy to decompose the resin matrix and extract the fiber, while the bottleneck lies in maintaining the structural integrity and physicochemical properties of the recycled fibers, along with reconstructing corresponding composites with performance efficiency. In this work, a two-step pyrolysis strategy is demonstrated to decompose the resin matrix and remove the carbon residues without damaging the internal structure of the recycled carbon fiber felts (rCFFs), followed by surface modification to facilitate the reconstruction of rCFFs-reinforced phenolic resin composites. The composites achieve remarkable electromagnetic interference (EMI) shielding performance in the X band with maximum EMI shielding effectiveness value of 70.5 dB, along with impressive flame-retardant performance under a high heat flux of 50 kW/m2. Besides, more than 80 % EMI shielding effectiveness is maintained after 10 pyrolyzing cycles by optimizing the pyrolysis parameters. Catering to maintaining the intrinsic properties of the recycled carbon fibers by proposing comprehensive recycling strategy, the synthesis of rCFFs-based materials is of great significance for promoting the substitution of pristine EMI shielding counterparts and the practical reutilization of carbon fiber resources. [Display omitted] [ABSTRACT FROM AUTHOR]