To further current knowledge of how strain effects the structure of impinging flames and how these effects play a role in the surface modification of polymer films. two premixed impinging flames are modeled using the SPIN application of the CHEMKIN software: in Case 1, a methane - air flame, and in Case 2, a methane - air flame with 4.5% nitrous oxide additive. In Case 1, the quenching activates six reactions that consume O, H, and OH, while H2O2 and HO2 are produced. In Case 2, the quenching and N2O additive further consume the oxidizing species, while HNO, N2O, NO, and NO2 are produced in significant quantities through activation of six additional reactions. It is shown that the strain applied to the flame by impingement on the cool stagnation surface leads to secondary reactions in the quench zone that are directly responsible for the modification of the polymer film surface.