Exploring Glass Fibers Modification Conditions and Designing Lightweight and Efficient Absorbers Based on Glass Fiber @Polypyrrole

Designability of glass fiber (GF) for microwave absorption is frequently neglected in buoyancy matrixes, which overcomes difficulties for their poor polarization loss to realize lightweight and efficient microwave absorption performance. In this study, GF coated with polypyrrole shell (GF@PPy) for multi-layered interface was successfully prepared through surface etching GF and then in-situ growth of PPy. According to the etching process of GF, GF@PPy-t40 (NaOH concentration with 16.67 mol/L, etching time with 40 min) demonstrates the efficient microwave absorption performance. Minimum reflection loss (RLmin) of GF@PPy-t40 (-10.40 dB, 3.0 mm) is 1.5 times that of GF@PPy-w10 (NaOH concentration with 2.78 mol/L) and 1.2 times that of GF@PPy-t60 (etching time with 60 min), which is ascribed to the enhancement of polarized sites caused by surface defects through appropriate etching concentration and time for NaOH. Based on the above etching conditions, we controlled the loading of in-situ polymerized PPy on GF through adjusting the concentration of pyrrole, realizing the impedance matching of 20 wt% GF@PPy in paraffin ring. GF@PPy-c60 (pyrrole concentration as 1.5 g) possesses the best microwave absorption performance, its RLmin is up to −30.40 dB (14.96 GHz, 1.5 mm) and effective absorption bandwidth (EAB) reaches to 4.8 GHz, which is ascribed to its excellent impedance matching. Especially, the density of GF@PPy-c60 can reach to 1.65 g cm−3, which is far below that of commercial GF (2.4–2.7 g cm−3). This modification lighters GF and effectively enhances microwave absorption performance, providing a basis for the radar stealth of GF in the marine environment.