Enhanced Dielectric Strength and Mechanical Properties in PMIA Micro-Nano Paper by Interface Plasma Fluorination Treatment

Poly(m-phenylene isophthalamide) (PMIA) is renowned for its superior insulating and mechanical properties, holding immense promise in ultrahigh-voltage transmission systems. To further enhance the mechanical robustness of nanofiber-based paper, microfibers have been employed as reinforcement fillers. However, interfacial issues have emerged as a challenge, compromising the insulation properties. In this work, we present the realization of synergistically enhanced breakdown strength and mechanical properties in the PMIA micro-nano composite paper, achieved by interface fluorination treatment. With an optimized fluorination time of 60 s, the composite structure becomes more compact, greatly enhancing its overall integrity. The fluorine-rich interface provides potential electron traps and hydrogen bond sites, which play a crucial role in enhancing both electrical insulation and mechanical properties. The breakdown strength is increased by 19.5%, achieving a high value of 295.6 kV/mm. Concurrently, Young’s modulus and tensile strength are enhanced to 4.04 GPa and 24.38 MPa with increases of 32.9% and 14.8%, respectively. However, it is noteworthy that excessive plasma fluorination can induce surface structural damage to microfibers, impeding the adhesion of nanofibers. It leads to a deterioration in both electrical and mechanical properties. Moreover, the optimized paper shows exceptional flexibility, foldability, and colorability, opening new avenues for their utilization in demanding electrical environments.