Dr Agnieszka Suliga

A deployment solution for a parabolic sail structure for solar photon thrusters (SPTs) is presented. SPTs decouple the function of collection and reflection of light, achieving many advantages over flat solar sails. Although recent and increasingly realistic studies have concluded SPTs an unattractive option, the motivation behind this work is to progress the novel SPT concepts by resolving two problems identified: presenting a feasible solution for deployment and maintaining tight control over the collector shape; and addressing the space durability of carbon-fibre reinforced epoxy-resin composites for long duration solar sailing missions. Laterally curved bistable reeled composites were manufactured in such a way that their beneficial structural properties and bistable behaviour have been complimented with improved environmental resistance. This was achieved by implementing a cycloaliphatic based coating system reinforced with silicon nano-additive. The effect of curvature and additive on the natural frequency were investigated. In addition, response to vacuum outgassing, UV resistance, surface degradation due to atmospheric oxygen and thermal stability were investigated and improved.

In this work, thin carbon fibre reinforced plastic (CFRP) structures were coated with an organic-inorganic resin system for improved resistance to the low Earth orbit (LEO) environment. Thin structures of this type have been proposed for use in solar sails and other large deployable structures. The ultra-light, long extendible members were primarily composed of aromatic, high stiffness epoxy resin (TGDDM) cured with aromatic polyamines. This resin system was chosen because the high aromatic content provides excellent stiffness and creep resistance that are critical for this application. However, the resin?s aromaticity contributes to degradation by ultraviolet radiation and oxidation. The proposed solution involves shielding aromatic rings and organic chemical bonds that are prone to degradation by UV rays, with a cycloaliphatic resin system additionally reinforced with silicon nanostructures. By applying surface coating a significant decrease in roughness was observed and the surface degradation due to UV radiation prevented.

The purpose of this study is to demonstrate the properties of novel nanocomposites, based on cycloaliphatic epoxy resin additionally reinforced with silicon-containing nanostructures (mono- or octa-functional POSS or nanosilica). The changes in properties are discussed for the varied combinations of cycloaliphatic epoxy with a curing agent (cycloaliphatic amine or anhydride) and the nanomodifier. The in uence of modification on thermal stability, curing behaviour, morphology, surface chemistry, and topography were studied with TGA, DSC, ATR-FTIR, XPS and LCM. The results show that when POSS and/or nanosilica are incorporated to the cycloaliphatic matrix they in uence curing behaviour and glass transition temperatures (Tg), where mono-POSS increases Tg and octa-POSS decreases it with respect to nanosilica. Mono-POSS produces silicon-rich surfaces but tends to agglomerate and increase surface roughness. Octa-POSS and nanosilica penetrate the polymer matrix more deeply and disperse more easily. From the selected modifiers, octa-POSS shows the highest thermal stability.

Carbon fibre reinforced plastics (CFRP) can be found as structural components in various space applications, including the field of ?gossamer? structures used as deployable masts, antennas or hinges. Many of these applications are missions in low Earth orbit (LEO), which is a particularly hazardous environment for polymers and organic materials, such as epoxy resins used in CFRP manufacturing. The incorporation of silicon derivatives in epoxy resin based CFRPs in order to create hybrid organicinorganic networking has been suggested as a way to prolong the life span of ultra-thin composite structures. Two ways of modification were considered during this study; incorporation of polyhedral oligomeric silsesquioxane (POSS) nanoparticles to create so called nanocomposites, and a mixture of POSS with a flexible polydimethylsiloxane (PDMS) in order to achieve a smooth, silicon-rich protective surface. Both mono-functional and octa-functional POSS were selected and their compatibility with aliphatic amine/epoxy resin system was evaluated. The conducted experiment was inspired by the Design of Experiments (DoE) theory to validate the degradation of properties. The suggested method allows the magnitude of individual effects that contribute to the composite ageing and the effectiveness of various silicon derivatives to be evaluated. The results of this study contribute to the development of protection strategies which could help lower the rate of LEO induced degradation of ultra-thin CFRP masts.

In this study, novel nanocomposites were created by incorporation of Silsesquioxane containing eight glycidylether groups (octa-POSS) into a cycloaliphatic epoxy cured by an anhydride. The developed resin system, with different nanoparticle concentrations, was used on the outer layers of an ultra-thin CFRP structure in order to provide better environmental resistance to the environment of low Earth orbit (LEO) which was tested in a ground-simulation facility. The developed resins were subjected to space-like degrading factors and their response to corrosion, radiation and elevated temperatures was monitored by mass loss, together with measuring changes in surface chemistry (ATR-FTIR), functionality development (contact angle measurement and XPS), roughness (scanning laser microscopy) and morphology (SEM). The influence of increasing octa-POSS content on thermo-mechanical properties was measured with DMTA and the strength and modulus of elasticity were determined by flexural test. The addition of octa-POSS in any loading improves the environmental resistance, however, the most significant retention of mass and mechanical and surface properties after space-like exposure was observed in the 20 wt% octa-POSS reinforced cycloaliphatic epoxy. The results presented here may contribute to the development of novel class of nanocomposites which can offer an extended service life in LEO.