Results of pre-flight tests of a novel cyanate ester laminate before exposure to low earth orbit

A novel patented cyanate ester (CE) resin, developed at the University of Bristol was selected for study in the Euro Materials Ageing 1 campaign (AO-2020-EMA, European Space Agency/CNES). Cyanate esters offer an attractive combination of low dielectric constant, coupled with high glass transition temperature and this example, incorporating silicon to enhance resistance to atomic oxygen in the space environment, demonstrates ease of processing. A carbon fibre reinforced polymer (CFRP) sample has been flown to the International Space Station (ISS) and is now being exposed on the Bartolomeo platform of the ISS for a period of 12 months. The flexural properties of 2.4-mm thick CFRP specimens were tested according to ASTM D790–10 and the flexural modulus was determined to be 68.81 (σ = 2.18) GPa. A sample of the laminate (25 mm × 25 mm × 2.44 mm) was machined with a shallow V shaped groove and subjected to a standard thermal outgassing test (ECSS-Q-ST-70-02C) which involved exposure to a vacuum pressure below 10 −5 mbar and a temperature of 125 °C for 24 h. The CE CFRP laminate lost a total of 0.53 % of its mass (the recovery mass loss was 0.15 %) and 0.01 % of the mass was collected as volatile material (subsequently identified as a polydimethylsiloxane). The CFRP sample was characterized by acquiring the UV–Vis-NIR reflection spectra from 200 to 2500 nm and by measuring the solar absorptance (α) and thermal emittance (ε). The reflectance for the CFRP sample increased from 0.105 (measured at 1500 nm) to 0.135, but the (α/ ε) ratio remained unchanged. When exposed to atomic oxygen (a flux of 3.43 × 10 15 atoms/cm 2 .s) the CFRP sample lost a mass of 13.863 mg ( i.e. an erosion yield of 4 × 10 −24 cm 3 /atom) after an ATOX fluence of 1.20 × 10 21 atoms/cm 2 . The CE CFRP sample passed its pre-flight tests and the samples are now undergoing exposure in low Earth orbit. • A novel cyanate ester is being exposed on the ISS for 12 months. • AO exposure (1.20 × 10 21 atoms/cm 2 ) led to an erosion yield of 4 × 10 −24 cm 3 /atom. • Minimal mass loss (0.53 %) after 10 −5 mbar/125 °C (24 h) 0.01 % was PDMS. • Ratio of α/ ε unchanged after exposure to equivalent of 2900 sun hours. • 2.4-mm thick CFRP specimens yielded a flexural modulus of 68.81 GPa.