Composites: Part A 204 (2026) 109641

Keywords: Smart materials, Environmental degradation, Microstructural analysis

Shape memory phthalonitrile (SMPN) resins have been exposed in low Earth orbit (LEO) environment aboard the China Space Station (CSS). The exposure experiment included one SMPN sample in its original flat shape and another in a temporary U shape. After exposure, the mass loss rate of the SMPN remains below 6.5%. Although SEM revealed severe surface erosion to a depth of approximately 28 mu m and FTIR indicated damage to the aliphatic segment of SMPN, the results of nanoindentation, DMA, and TGA tests show that the fundamental properties of the exposed SMPN remained largely unaffected. It is worth noting that the SMPN sample with a temporary U shape still retained its temporary shape after exposure and could recover its original shape upon thermal stimulation, achieving a shape recovery rate of approximately 97%. Microstructural analysis of the recovery sample indicates that the outer surface of the exposed U-shaped SMPN displays gradient damage characteristics, which could inform the optimization of damage-resistant designs in spacecraft structures. Despite the surface erosion, this study demonstrates that the SMPN maintains stable performance after space exposure, indicating its potential to serve as a material suitable for space environments.

Rongxiang Hu, Fenghua Zhang, Yanju Liu, Liwu Liu , Zhengxian Liu, Jinsong Leng

Low earth orbit environment effects on shape memory phthalonitrile resins.pdf