We propose a mathematical model of heat-mass exchange processes in polymeric wound composite under solidification. The model takes into account the processes of moisture evaporation and isolation of gasses of the products of reaction of solidification. Based on the results of numerical simulation of heat-mass exchange, it is revealed that the growth of pressure produced by gas isolation in composite polymeric materials under solidification can bring the material to the rise of strains in a non-solidified material, which can be sufficient for destruction of continuousness of the composite and for the growth of defects (cavities or delaminations).