由生物材料制备的绿色碳泡沫的物理及电磁屏蔽性能

摘要

以梧桐树含纤维的果实为原料、煤焦油沥青为粘合剂,通过粉末模塑法制备了100%绿色碳泡沫,目的是采用生物材料制备高强度,且可应用于物理、热和电磁屏蔽领域的多孔碳泡沫.在1000℃下不使用任何外部保护性气体,通过对梧桐树种子热解进行快速碳化.为比较分析,模制过程中在一些样品中混入了5%(质量分数)的氯化铁.氯化铁作为石墨化催化剂和活化剂,使材料比表面积从88增加到294 m2/g,弯曲强度降低25%.由于材料中引入较多的石墨成分,其热稳定性得到改善,但热导率提高有限(从0.22提高到0.67 W/(m·K)).经催化得到的碳泡沫在X波段的电磁屏蔽效能在20 dB以上,反射率仅为8.26%~10.33%,表明吸收损耗是占主导地位的电磁屏蔽机理.这种新材料轻质、高度多孔,保留有机生物材料互连多孔形态,有望应用于高温隔热材料领域.%100% green carbon foam from the fibrous fruits ofPlatanus 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 ℃ 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.