INFLUENCE OF POSS ON DURABILITY OF EPOXY BASED SHAPE MEMORY POLYMER NANOCOMPOSITE IN THE LOW EARTH ORBIT SPACE ENVIRONMENT

Thermally activated shape memory polymers (SMPs) can memorize at low temperature a temporary shape and return at higher temperature to their permanent shape. In the last decades, extended research has been devoted to studying the properties of different SMPs, resulting in numerous SMPs with a wide range of properties. Due to the higher strength-to-weight ratio of the SMP compared to metallic parts, one potential application is to replace components fabricated from heavy metals that are used in spacecraft; for example, deployable space systems in satellites, which operate in the low-Earth orbit (LEO). One of the major requirements from materials that are used in LEO is to be durable to atomic oxygen (AO). Unprotected polymers will erode in LEO by AO at a rate of ~100 µm per year. A potential solution to this problem is to incorporate Polyhedral Oligomeric Silsesquioxane (POSS) molecules into the polymer backbone, forming a SiO₂ passivation layer upon interaction with AO.

In this work, we studied the influence of two types of POSS, having amine and epoxide side groups, on the durability of epoxy-based SMPs to AO, as well as the POSS influence on the SMPs` deployment properties. The ratio between the components was determined to preserve the molar ratio between the amine and the epoxide groups. The samples were thermally cured and the durability to AO was tested in a ground–based AO simulation facility, based on a RF plasma source. The results demonstrate the influence of the POSS on the durability of the SMPs to AO through formation of a passivation layer, as well as its influence on the shape memory deployment velocity.