Organic-inorganic PVA/Carbon microwave absorption composites: Tuning rheology to enable structurally diverse fabrication

Organic-inorganic microwave absorption composites have garnered significant interest due to their low density, excellent processing properties and adjustable functional properties. Meanwhile, there is an obvious optimized loop relationship between their processing strategies, composite structures and microwave absorption properties. However, there has been no systematic exploration of the relationships among their rheological properties, processing strategies, structure and properties. Within organic-inorganic microwave absorption composites, Polyvinyl alcohol (PVA)/microwave absorbent composites have tunable rheological properties. Hence, in this study, the rheological properties of PVA/N-doped carbon microwave absorbent (CMA) composites are investigated, especially viscosity and viscoelasticity. Based on their tunable rheological properties, PVA/CMA composites with diverse structures and properties are prepared, including fibers (one-dimensional), films (twodimensional), aerogels (three-dimensional), and textile composites. Variable rheological properties lead to different processing strategies, which result in PVA/CMA composites with different structures and microwave absorption properties. The results demonstrate that PVA/CMA composites are well-suitable for blade coating and aerogel molding when the G'/G" < 1, while they are more suitable for wet-spinning and screen-printing when the G'/G" > 1. Moreover, owing to its porous structure, the aerogel achieves a reflection loss of-56.46 dB and an absorption bandwidth of 7.15 GHz, which is superior to the other three composites. This study provides an important reference for the diversified preparation of PVA/microwave absorbent composites in terms of structure and properties.