Photochemical nanomodification of polymer surfaces: aerospace applications

Abstract

Engineering operations in space require the optimization of a wide variety of procedures and the design of new, lighter and more durable materials. One of the main concerns of human-operated space activities is exposure to radiation, attaining doses that may eventually exceed those considered within safety limits. Polymers are perhaps the most promising materials for radiation absorption (due to their relatively high hydrogen content), generally low specific weight and wide variety of mechanical properties. Their response to space environment is, however, greatly dependent on factors such as chemical composition, thermal treatment and stress state under service conditions. Their structural makeup can lead to a decrease in durability, especially under harsh radiation (e.g. ultraviolet) and/or chemical (e.g. ozone)attack. It is known that the response of different kinds of polymers can be very different, from generation of surface roughness (and subsequent increase in surface area) to breakup and disintegration. This work aims to study in a systemic way the effects of combined ultraviolet/ozone irradiation on the surface properties of a variety of polymers, in order to shed light on the nanoscale mechanisms of surtface modification. Treated and reference samples will be studied by means of Atomic Force Microscopy and both optical (interferometric) and mechanical profiling. Images obtained will be processed with professional software in order to obtain quantitative parameters to assess the level of (nano)modification in each case. This information will eventually be useful for the assessment of different applications of polymer materials in the space environment.