Transparent and mechanically robust poly (para-phenylene terephthamide) PPTA nanopaper toward electrical insulation based on nanoscale fibrillated aramid-fibers

Due to chemically inert surface and poor interfacial interaction, PPTA (poly (para-phenylene terephthamide)) fiber-based specialty paper suffers from microvoids and limited physical properties. In this work, PPTA pulps were treated by DMSO/KOH to achieve nanofibrillated aramid fibers(similar to 20 nm in diameter), which can form stable aqueous dispersion. In this way, PPTA nanopaper with densely-packed nanofiber networks was prepared through vacuum-assisted filtration process, and the interfacial interaction between PPTA nanofibers was further enhanced by hot-pressing. It is noteworthy that PPTA nanopaper turns to be transparent and remains good flexibility in comparison with PPTA micropaper. More importantly, PPTA nanopaper shows a high mechanical strength of similar to 159.6 MPa, high Young's modulus of similar to 4.2 GPa, and elongation at break of similar to 4%, respectively. Meanwhile, PPTA nanopaper possesses an increased UV-resistant property mainly due to the densely-packed paper structure. The Weibull distribution model predicts the dielectric breakdown strength of PPTA nanopaper as high as 92.8 kV/mm.