A Flexible Sandwich Structure Carbon Fiber Cloth with Resin Coating Composite Improves Electromagnetic Wave Absorption Performance at Low Frequency

In order to improve the electromagnetic wave absorbing performance of carbon fiber cloth at low frequency and reduce the secondary pollution caused by the shielding mechanism, a flexible sandwich composite was designed by a physical mixing coating process. This was composed of a graphene layer that absorbed waves, a carbon fiber cloth layer that reflected waves, and a graphite layer that absorbed transmitted waves. The influence of the content of graphene was studied by a control variable method on the electromatic and mechanical properties. The structures of defect polarization relaxation and dipole polarization relaxation of graphene, the interfacial polarization and electron polarization of graphite, the conductive network formed in the carbon fiber cloth, and the interfacial polarization of each part, combined together to improve the impedance matching and wave multiple reflections of the material. The study found that the sample with 40% graphene had the most outstanding absorbing performance. The minimum reflection loss value was −18.62 dB, while the frequency was 2.15 GHz and the minimum reflection loss value compared to the sample with no graphene increased 76%. The composites can be mainly applied in the field of flexible electromagnetic protection, such as the preparation of stealth tent, protective covers of electronic boxes, helmet materials for high-speed train drivers, etc.

Activated Carbon Fiber Cloth/Biomimetic Apatite: A Dual Drug Delivery System

A biomaterial that is both bioactive and capable of controlled drug release is highly attractive for bone regeneration. In previous works, we demonstrated the possibility of combining activated carbon fiber cloth (ACC) and biomimetic apatite (such as calcium-deficient hydroxyapatite (CDA)) to develop an efficient material for bone regeneration. The aim to use the adsorption properties of an activated carbon/biomimetic apatite composite to synthetize a biomaterial to be used as a controlled drug release system after implantation. The adsorption and desorption of tetracycline and aspirin were first investigated in the ACC and CDA components and then on ACC/CDA composite. The results showed that drug adsorption and release are dependent on the adsorbent material and the drug polarity/hydrophilicity, leading to two distinct modes of drug adsorption and release. Consequently, a double adsorption approach was successfully performed, leading to a multifunctional and innovative ACC-aspirin/CDA-tetracycline implantable biomaterial. In a second step, in vitro tests emphasized a better affinity of the drug (tetracycline or aspirin)-loaded ACC/CDA materials towards human primary osteoblast viability and proliferation. Then, in vivo experiments on a large cortical bone defect in rats was carried out to test biocompatibility and bone regeneration ability. Data clearly highlighted a significant acceleration of bone reconstruction in the presence of the ACC/CDA patch. The ability of the aspirin-loaded ACC/CDA material to release the drug in situ for improving bone healing was also underlined, as a proof of concept. This work highlights the possibility of bone patches with controlled (multi)drug release features being used for bone tissue repair.