Changes in the properties of a polymer or a polymer-based product under the influence of such environmental factors as heat, light, or chemicals can be desirable or undesirable. Scientists from many countries look at some efforts to induce the first and suppress the second. Among their examples are flame retardancy of polyurethane foams, the influence of epoxy-amine ratio on the degradation of epoxy-silica hybrid materials, and modeling dynamical-mechanical properties of vinylester and unsaturated polyester with glass fiber reinforced composites.