In the present work, blends between poly(methyl methacrylate) (PMMA) or its copolymer with butyl methacrylate P(MMA-co-BMA) and poly(ethylene-co-vinyl acetate) (EVA) rubbers obtained applying the reactive blending principles were deeply investigated to clarify the chemistry of the system. A copolymeric phase, which is created in situ, was isolated and its chemical structure was determined through NMR analysis. The blends were also crosslinked with a flexible dimethacrylate to realize semi-interpenetrated networks. The blends were characterized for their properties of interest (mechanical and optical behaviors). Particularly, an accurate investigation of the optical properties as a function of the temperature was performed. (c) 2006 Wiley Periodicals, Inc.