Physical and electromagnetic shielding properties of green carbon foam prepared from biomaterials
(1. Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072, China;
2. School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China)
Abstract: 100% green carbon foam from the fibrous fruits of Platanus Orientalis-L (Plane) along with the tar oil as binder has been prepared using a powder molding technique. The objective was to develop a porous monolithic carbon from biomaterials with a considerable strength necessary for various physical, thermal and electromagnetic shielding applications. Fast carbonization was carried out at 1000 °C under the cover of Plane tree pyrolyzed seeds without using any external protective gas. For comparative analysis, some samples were mixed with 5% (mass fraction) iron chloride during the molding process. Iron chloride being a graphitization catalyst and activating agent helped in increasing the specific surface area from 88 to 294 m2/g with a 25% decrease in flexural strength. Thermal stability was improved due to the incorporation of more graphitic phases in the sample resulting in a little higher thermal conductivity from 0.22 to 0.67 W/(m·K). The catalytic carbon foam exhibited shielding effectiveness of more than 20 dB over the X-band frequency. Absorption was dominant with only 8.26%-10.33% reflectance, indicating an absorption dominant shielding mechanism. The new material is quite suitable for high temperature thermal insulation being lightweight, highly porous with interconnected porous morphology most of which is preserved from the original biomaterial.
Key words: carbon foam; biomass; pyrolysis; powder molding; electromagnetic properties