Design of sandwich-structured para-aramid paper with polyphenylene sulfide non-woven fabric for enhancing mechanical properties and breakdown strength

The rapid development of national defense, military industry, and aerospace puts forward higher requirements to the mechanical property, breakdown strength, dielectric properties, and heat resistance of high-performance aramid paper. However, the vast majority of aramid paper-based materials can hardly have a combination of satisfactory high mechanical properties and breakdown strength due to the porous structure of paper-based materials. Herein, we report a para-aramid chopped fibers/polyphenylene sulfide (ACFs/PPS) composite paper with a sandwich structure by designing the structure of aramid paper. Dense PPS microfiber membrane as robust armor filled and repaired the voids and defects on ACFs/PPS composite paper. Additionally, strong barrier interfaces between PPS film and ACFs/PPS composite paper effectively slow down the transmission of voltage to the inside of the composite paper. Thus we obtain the sandwich-structured ACFs/PPS composite paper with excellent mechanical strength (158.7 MPa) and breakdown strength (55 kV/mm), which are almost 1.5 and 2.5 times higher than ACFs/PPS composite paper, respectively. Besides, excellent mechanical properties and breakdown strength are wonderfully integrated with superior dielectric properties (tanδ <0.0035), chemical stability, and thermal stability (DTGmax > 575 °C), far superior to reported aramid paper-based materials. This work plays an important role in fabricating fabulous multi-attribute combinations of aramid paper-based materials and can also be extended to other materials and structures.