Polymerization Processes of Epoxy Matrix Composites under Simulated Free Space Conditions

Abstract

The creation of large-size space constructions by deploying structures needs a method for making the shell material rigid after unfolding. The best method is a chemical reaction. There is a negative influence of space environment (high vacuum, atomic oxygen flux, cosmic rays, sun irradiations, sharp temperature variations) on a liquid polymer matrix and on the polymerization process. The authors suggest that the space environment can initiate the polymerization reaction, for example a curing reaction of epoxy resin composition. This paper contains the results of experiments on polymerization processes under the action of separate space environment factors: vacuum and plasma action. For the simulation of space plasma a discharge of microwave plasma and radio-frequency plasma were used. Structures of polymer materials cured under plasma and in the usual curing conditions were compared. The results on degradation processes in uncured epoxy resin under plasma action were taken into account for the curing kinetic study. The fornation of new active groups in liquid composition under plasma action and the ability of new groups to take part in the curing reaction was analysed. A process of layer mixing in uncured epoxy resin during plasma action was observed. The mixing of oxidized layers with initial bulk layers of resin leads to an acceleration of the curing reaction. Due to layer mixing the plasma treatment becomes a method for bulk modification of polymers. A method of utilization of negative free space factors for the curing process of composite materials in free space is proposed. The space plasma can be used for the polymerization process of composite materials on Earth orbit. The composite samples of glass fibres impregnated by the epoxy matrix with 5 mm thickness were polymerized in plasma discharge at low pressure without formation of bubbles.