Impact of cryogenic aging and test-environment on mechanical properties and tribological performance of PI-based materials

This study investigates the effect of test-environment, temperature, and cryogenic aging in liquid nitrogen for 5 months on mechanical and tribological performance of polyimide (PI) and PI composites. Tribological tests were conducted at 25 °C in air, and at both 25 °C and −100 °C in a high vacuum (10 -5 Pa) environment. Impact of cryogenic aging, testing condition on PI-based materials varied depending on the polymer structure and composition. Cryogenic aging led to embrittlement, increasing the coefficient of friction and wear rate up to 77 % and 165 %, respectively. Some polyimides exhibited the lowest coefficient of friction (0.04) in vacuum at 25 °C, while the temperature reduction to −100 o C in vacuum generally decreased the tribological performance, increased contact stresses and abrasive wear of the materials. • Cryogenic aging impacts fracture toughness depending on structure and filler content. • Tribological performance was affected by long-term cryogenic aging. • Test-environment, temperature, and polyimide structure influence wear mechanisms.