Extreme Cold Damages Polymer Seals Used in Spacecraft and Cryogenic Equipment
Researchers found that repeated freezing cycles permanently weaken polyimide materials commonly used in aerospace, refrigeration, and space systems—making them more prone to creeping and failure at room temperature. The discovery could force manufacturers to redesign critical seals and gaskets, or replace them more frequently, affecting supply chains and maintenance costs across industries dependent on cryogenic technology.
Originaltitel: Influence of Cryogenic Cyclic Aging on Room-Temperature Mechanical and Tribological Performance of Polyimide-Based Materials
<p>Cryogenic environments impose severe thermal and mechanical stresses on polymercomponents, yet the effects of long-term cryogenic cycling on their subsequent room-temperatureperformance remain insufficiently understood. This study investigated the influence ofcryogenic cyclic aging on the mechanical and tribological behaviour of polyimide (PI)-basedmaterials, including neat PI and composites reinforced with MoS2, graphite, and/or PTFE.Repeated cryogenic cycling was followed by mechanical characterisation and tribologicaltesting at 25 ◦C in air and vacuum. This work systematically compares neat and filled PImaterials after cryogenic cyclic aging and correlates mechanical changes with transfer-filmformation and wear behaviour. Cryogenic cyclic aging had only minor effects on weightand thermal stability but significantly altered the viscoelastic behaviour, increasing creepand residual strain, with variations depending on the polymer structure and filler content. Fracture toughness showed a statistically significant improvement only for PI2 (upto 93%). Changes in PI1, PI3, PI4, and PI5 fell within the experimental scatter and wereinterpreted as non-significant trends. In air, abrasive wear dominated in unreinforcedPI, while graphite/PI composites exhibited adhesive wear and improved transfer filmformation, reducing wear rates by up to 26%. In vacuum, the wear rate of aged graphite/PIincreased by up to two orders of magnitude.</p>