Lexan (polycarbonate) is much more resistant to breaking than Plexiglas (acrylic). Thick Lexan is used in "bulletproof" applications. However, the down side is that Lexan is easier to scratch and yellows faster than Plexiglas. "Scratch-resistant" polycarbonate actually has a thin layer of acrylic on the surface to resist scratches. Neither acrylic nor polycarbonate will be anywhere near the scratch resistance of glass. Also, polycarbonate or acrylic will be much more flexible than glass. If the window is large, it will move in and out easily when pushed, even lightly.
Steve
