Polycarbonate is a lot tougher than acrylic. While acrylic is about eight times stronger than untempered glass, polycarbonate is about 200 times stronger. It's used in DOT-approved helmet face shields, as well as racecar windows and machine-tool safety shields. Laminated layers of polycarbonate can even be used to stop bullets, though you don't want to annoy anyone that much if all you have between you and a high-caliber argument is a motorcycle windshield. Polycarbonate is easier to scratch, but windshield manufacturers get around this by adding a protective layer of hard-coating.