Facile fabrication of sepiolite functionalized composites with tunable dielectric properties and their superior microwave absorption performance
2020
Shang, Qiong | Feng, Huixia | Feng, Zeyu | Chen, Nali | Tan, Lin | Qiu, Jianhui | Wu, Hongjing
Although various materials have been studied for the purpose of microwave absorption (MA), natural sepiolite (SEP) has never been reported as MA absorber. Herein, the series of sepiolite@polyaniline composites (SEP@PANI-x) with “skeleton/skin” structure were fabricated through a facile in-situ polymerization technique and firstly developed as MA materials. The electrical conductivity and dielectric properties can be well controlled via modulating the PANI content in the composites. With a lower mass ratio of 30 wt%, it is worth noting that the optimized SEP@PANI-50 could simultaneously display the optimal minimum reflection loss (RLₘᵢₙ) of −50.23 dB and effective absorption bandwidth (EAB, RL < -10 dB) of 5.01 GHz with thicknesses of 2.5 and 1.8 mm, respectively. Moreover, when changing absorber thickness (1.5–5.0 mm), the RLₘᵢₙ values lower than −20 dB (99% absorption) are all achieved and the EAB ranges the entire Ku, X, and C bands. Such excellent MA performance comes from rich conductive network and polarization relaxation, which ultimately balance the impedance matching and attenuation ability. In view of its facile synthesis route, low-cost, lightweight and excellent MA performance, SEP@PANI-50 would be a very promising MA candidate in many practical applications. More importantly, we also think that our findings will expand the application of SEP-based composites in the electromagnetic field.
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