Novel polyimide-hexagonal boron nitride nanocomposites for synergistic improvement in tribological and radiation shielding properties

Abstract

Polyimide (PI), a high-performance polymer with a high strength-to-weight ratio, thermal stability up to 330 °C, and chemical resistance, is a candidate material for aerospace and automotive applications. However, the poor tribological performance at elevated temperatures and radiation-induced brittle fracture threaten the durability of PI materials. To counter these challenges, novel hexagonal boron nitride (h-BN) based PI nanocomposites were prepared at 2 wt% and 5 wt% h-BN using direct forming. The dispersion of h-BN in the PI matrix was facilitated using ball milling. The glass transition temperature (Tg) of PI-2 wt% and 5 wt% h-BN increased by 18 °C and 20 °C, respectively, compared to neat PI. Tribological characterization using dry ball-on-disk sliding revealed an improvement in wear rate of ∼56 % and ∼70 % for PI-2 wt% and 5 wt% h-BN compared to neat PI at room and high temperatures (300 °C). PI-hBN nanocomposites were subjected to a neutron radiation source. The linear and mass absorption coefficient of PI-2 wt% and 5 wt% h-BN enhanced significantly by 1.9 and 2.2 times, respectively, compared to neat PI. The developed nanocomposites, with their excellent tribological behavior and neutron shielding capacity, have great potential as multifunctional materials for aerospace applications.