Model of moisture absorption materials used in the manufacture of spacecraft antennas

In this case study the processes occurring in finding the polyimide films and carbon plastic in the air with different humidity have been analyzed. Various polymeric materials including polyimide film and carbon fiber are used in spacecraft (SC) manufacture. For achievement of desired radio characteristics for composite reflector antennas are coated with a thin reflective metal layer, usually aluminum. It is necessary to know the volume of moisture contained in the bulk material, for elimination of corrosion risk for the sprayed layer. In case of moisture-absorption of the polyimide film and CFRP, the diffusion of water molecules contained in the atmosphere into the material occurs. Fick’s mathematical model is used to determine the amount and sorption kinetics of moisture contained in the ambient air. On the basis of the Fick's equation and conditions arising in the construction of models for thin polymeric materials the equation for calculating the dynamics of moisture absorption polymeric materials was obtained. According to the resulting model of moisture absorption, the diffusion coefficients of materials by thermo gravimetric analysis and comparison of the results obtained, with this model can be determined. The production and selection of material with low moisture absorption value is a trans-promising direction in materials applied to the rocket and space industry. The materials with a small amount of moisture absorbed by the SC allow a longer active life (CAC) and the need for future up-formulations, in particular - with cryogenic equipment.