In case of rubber-toughened plastics using a transparent polymer, however, it is significantly difficult to keep the transparency because of the light scattering at the
interface between two materials due to the difference in the refractive index [5,6]. Furthermore, it has been known that the light scattering can be reduced by adjusting the
refractive indices of both phases [7–9]. Ethylene–vinyl acetate copolymer (EVA), known as a rubbery material