Low-Earth-Orbit space environment characteristics of nano-filler reinforced polymer matrix composites

Abstract

In this thesis, low Earth orbit (LEO) space environment characteristics of nano-filler reinforced epoxy matrix nanocomposites were investigated. Prior to the investigation, understanding of LEO space environment effects on typical composite materials was carried. Designing and manufacturing LEO space environment simulation facility, simulation of major LEO space environment hazards characterized by high vacuum $(~10^{-5} Torr)$, ultraviolet (UV) radiation (<200nm wavelength), temperature cycling (-70℃ ~ 100℃), and atomic oxygen atmosphere $(AO flux of ~10^16 atoms/cm^2·s and kinetic energy of ~0.04eV)$ took place. Under the simulated LEO space environment, graphite/epoxy composites, which have been widely applied to space structures, were tested to study the LEO space environment effects on the composites. Tensile properties, as well as mass loss of the graphite/epoxy composites, after being exposed to AO atmosphere and the synergistic LEO space environment, were investigated. The surface morphology of the composites under LEO space environment effects was also observed by scanning electron microscope (SEM). Experimental results showed that LEO environment and its synergistic effects cause considerable damage to the surface and material properties of composites. Multi-walled carbon nanotube (MWNT) reinforced and $Al_2O_3$ nanotube reinforced epoxy matrix nanocomposites were fabricated with different nanotube weight percent (wt.%) concentrations. Ultra-sonication and homogenization were simultaneously employed to disperse the nano-fillers into epoxy resin. Both nano-filler reinforced composites were tested under the simulated LEO environment. LEO space environment characteristics of MWNT/epoxy and $Al_2O_3$ nanotube/epoxy nanocomposites were investigated. The tensile and thermal properties, as well as, mass loss of the nanocomposites with various nanotube concentrations (0.0-2.0 wt.%) after being exposed to the simulated LEO environment effects were investiga...