Copolymer systems based on various molar ratios of methyl methacrylate (MMA)/butyl acrylate (BA) and different mass content of N-methylolacrylamide (NMA), as a crosslinking agent, were investigated. The influence of temperature, 150 degrees C, under conditions similar to those used in the textile industry, and effect of ultraviolet (UV) irradiation were examined. The changes of mechanical properties were found to be connected with the cross-linking and/or degradation mechanisms. The effect of copolymer composition on the mechanical properties was established, especially during UV degradation.