Carbonized Silk Fiber Mat: a Flexible and Broadband Microwave Absorber, and the Length Effect

• Published in: ACS sustainable chemistry & engineering 2021-09, Vol.9 (38), p.12747-12754
• Main Authors: Hou, Yi, Quan, Jing, Su, Xinran, Deng, Chaoran, Yang, Yong, Khoo, Boo Cheong
• Format: Article
• Language: English
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.1c02857

Sustainable manufacture of renewable materials without compromising performance remains a challenge to material scientists. Biomass material is acknowledged as a cost-effective approach to alleviate the situation. In this work, carbonized silk fiber (average 5 μm diameter) mats were derived from silkworms through degumming and subsequent one-step carbonization process at high temperature. It is demonstrated that the resultant mats are able to show great flexibility and high-efficiency microwave attenuation performance by optimizing the annealing process. At the optical carbonization temperature of 650 °C, the carbonized silk fiber mat/silicone composite could exhibit a minimal reflection loss (RL) value of −70 dB at 17.6 GHz and 2.5 mm thickness. At 3.2 mm thickness, an effective absorption bandwidth (EAB, RL < −10 dB) as wide as 8.7 GHz (9.3–18 GHz) is achieved. Such a broad bandwidth is mainly attributed to the long fiber length and well-connected conductive network in the mat, which leads to promoted permittivity at a low filling ratio (5 wt %). Combining the great flexibility, broad bandwidth, lightweight, and low cost with a simple fabrication process, the established carbonized silk fiber mat could be an environmentally friendly alternative to currently existing traditional absorber materials for microwave attenuation in electromagnetic compatibility applications.