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

Abstract

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.

In situ preparation of molybdenum-dioxide-incorporated carbonized silk fiber and its application in supercapacitors

“…The conductivity of the CSF derived from each group generally supports the variation in graphitization degree indicated by the Raman spectra, as it has been reported that carbonaceous materials with higher graphitization degrees tend to have higher electrical conductivities ( Hou Y. et al, 2021 ). It can be seen from Supplementary Table S10 that the conductivity of the CSF started to rise when the Mo feeding dosage was 0.1 g/L, reaching its maximum at a dosage of 1 g/L.…”

Recent advance in three-dimensional porous carbon materials for electromagnetic wave absorption

“…Silk is one of the most abundant natural protein fiber materials. In Yang's work [107], silkwormsderived carbonized silk fiber mats (SCF) were successful fabricated, which showed an RL min value of −70 dB at 17.6 GHz and 2.5 mm, and the EAB value of 8.7 GHz (9.3-18 GHz) at 3.2 mm thickness (Fig. 9f).…”

Ultralight biomass-derived carbon fibre aerogels for electromagnetic and acoustic noise mitigation

“…29 It was proved in our previous study that the carbonized silkworm fibre is indeed a great filler for wideband microwave attenuation. 30 In this work, we demonstrate that the dielectric properties of the carbonized silk fibre mat can be well manipulated by the control of the annealing temperature, which can be applied to develop silk derived carbon fibre aerogels (SAs) with gradient impedance through the laminated structure for low reflection EMI shielding. After optimization of the annealing process, the aerogel shows great flexibility, an ultralow density of ∼15 mg cm −3 and an EMI absorption power coefficient ( A ) as high as 0.98 (nearly 20 dB attenuation).…”