Abstract: A general approach to modeling the mass loss of polymer composites under space conditions is proposed. The case of the effect of radiation-stimulated evaporation on the mass loss of the polymer composite in vacuum upon irradiation with 10–50 keV electrons is considered in detail. It is shown that the energy loss and density of the electron flow, as well as the mass fraction of the filler in the material, affect the mass loss of the polymer composite. In particular, it is found that the mass loss of the studied materials when irradiated in vacuum at a fixed density of the radiation energy flux decreases with increasing electron energy Е0. This is explained by the fact that the smaller Е0, the greater the stopping power; therefore, in larger quantities and in a thinner surface layer of the material, radiolysis products are produced. In this case, the gas permeability of the irradiated layer of the material grows with the energy absorbed in it, and the products of radiolysis are released into the vacuum more quickly. It is established experimentally that, at φ = 1011 cm–2 s–1, the mass loss of the materials studied occurs mainly via radiation-stimulated gas release, and at φ = 1012 cm–2 s–1 and the value of Е0 = 10 keV, the weight of the evaporated material in the total loss mass of polymeric material is more than 50%. © 2020, Pleiades Publishing, Ltd.