State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, People's Republic of China.
Nanoscale Res Lett. 2013 Jun 22;8(1):293. doi: 10.1186/1556-276X-8-293.
A kind of web-like carbon with interconnected nanoribbons was fabricated using bacterial cellulose pyrolyzed at various temperatures, and the microwave dielectric properties were investigated. Bacterial cellulose was converted into carbonized bacterial cellulose (CBC) with a novel three-dimensional web built of entangled and interconnected cellulose ribbons when the carbonization temperature was below 1,200°C; the web-like structure was destroyed at a temperature of 1,400°C. Composites of CBC impregnated with paraffin wax exhibited high complex permittivity over a frequency range of 2 to 18 GHz, depending on the carbonization temperature. Both real and imaginary parts were the highest for CBC pyrolyzed at 1,200°C. The complex permittivity also strongly depended on CBC loadings. For 7.5 wt.% loading, the real and imaginary permittivities were about 12 and 4.3, respectively, and the minimum reflection loss was -39 dB at 10.9 GHz. For 30 wt.% loading, the real and imaginary permittivities were about 45 and 80, respectively, and the shielding efficiency was more than 24 dB in the measured frequency range and could be up to 39 dB at 18 GHz. The electromagnetic properties were assumed to correlate with both the dielectric relaxation and the novel web-like structure.
采用不同温度热解的细菌纤维素制备了具有互联纳米带的网状碳，并研究了其微波介电性能。当碳化温度低于 1200°C 时，细菌纤维素转化为碳化细菌纤维素（CBC），形成由缠结和互联纤维素带构成的新型三维网状结构；当温度达到 1400°C 时，网状结构被破坏。石蜡浸渍的 CBC 复合材料在 2 至 18GHz 的频率范围内表现出高复介电常数，这取决于碳化温度。在 1200°C 下热解的 CBC 的实部和虚部最高。复介电常数还强烈依赖于 CBC 的负载量。在 7.5wt.%的负载量下，实部和虚部介电常数分别约为 12 和 4.3，在 10.9GHz 时最小反射损耗为-39dB。在 30wt.%的负载量下，实部和虚部介电常数分别约为 45 和 80，在测量的频率范围内屏蔽效率超过 24dB，在 18GHz 时可达 39dB。电磁性能与介电弛豫和新型网状结构有关。
