| Within this study, four developments are presented. First, the Atomic Oxygen Beam Facility at the University of Toronto Institute for Aerospace Studies is further characterized by measuring the charged species component of the beam (mole fraction = 4 x 10-5) and the beam velocity energy spectrum (Maxwellian-like distribution with a peak at 2.1 eV).; Second, using the atomic oxygen beam facility, a series of parameters which relate the hyperthermal atomic oxygen erosion yield of a hydrocarbon polymer to its chemical content and structure is experimentally verified. Ultimately, it was determined that the erosion yield is related linearly to an effective carbon content parameter (gamma). The gamma-parameter accounts for the relative amount of carbon in the polymer, and the role of intramolecular oxygen in determining the reactability of the polymer. Conclusions are reached with respect to the roles of the two driving forces in the eroding process; the chemical potential of the species involved and the kinetic energy of the atomic oxygen.; The third development, which again relates to the erosion process of hydrocarbon polymers, is an original reaction scheme proposed for the interaction of atomic oxygen with DuPont's polyimide KaptonRTM. This scheme is based on the well studied interaction of molecular oxygen with polyimides. The purpose of deriving this reaction scheme is to develop an applied example using the gamma-parameter assumptions. The derivation process concludes with the enumeration of the reaction products of the hyperthermal atomic oxygen interaction process with KaptonRTM.; Taking the knowledge gained about how and why atomic oxygen erodes polymers, and applying it to solve an important engineering problem (ie. inhibiting atomic oxygen erosion in low Earth orbit) is the goal of the final development. Two surface modification processes are explored. Plasma fluorination of Kapton RTM was attempted with only limited success, resulting in a maximum reduction to approximately 50% of the typical untreated sample erosion yield. A second technique, known as 3-Step Silylation or the PhotosilTM Process, was demonstrated successfully with a two order-of-magnitude reduction in erosion yield for a variety of materials including: KaptonRTM , MylarRTM, PEEK, polyethylene, graphite reinforced PEEK and epoxy composites, and the graphite fibres themselves. |
