A plastic with special coating that is 250 times stronger than glass and 30 times stronger than acrylic.
Lexan is the brand name for polycarbonate sheet and resin in a wide range of grades.
Lexan is a polycarbonate plastic. Fiberglass is exactly that, fibers of glass bound together with a resin.
Polycarbonate
Most riot shields list the material of construction as Lexan, the trade name for the polycarbonate polymer. The young's modulus of polycarbonate is 2.0-2.4 GPa (gigapascals).
You can buy the panels on multiple websites. One site I found is www.eplastics.com Home Lexan Polycarbonate. They seem to have different brands to look through.
The Resistance to Attack by Aviation Phosphate Ester Fluids (of which Skydrol is) with Polycarbonate (Lexan) is listed as "Poor" and Skydrol "Not Recommended."See also the associated links.
Usually it's a thin shell(lexan, polycarbonate etc) and then a polystyrene(or similar) foamed liner to provide cushioning.
Polycarbonate is a tough and versatile plastic used in bulletproof windows, cellphone casings and eyeglasses. Dr. Hermann Schnelle of Bayer in Germany invented the polycarbonate resin in 1953, just a week before Dr. Daniel Fox of General Electronics made the same discovery. Lexan is the brand name of polycarbonate.
Lexan is the stronger of the two. Polycarbonate is the generic name and is 25 times stronger than acrylic or plexiglass. It is also stronger the PETG another type of clear plastic. It is also bulletproof and you can hammer a nail straight through without breaking the material. Here's some more info on this page about Polycarbonate and other plastics...
Harley windshields are typically made of Lexan which is a hard-coated polycarbonate material. This material is scratch resistant, durable and distortion-resistant.
In order to make a durable sign, a durable type of plastic must be found. Polycarbonate, or lexan, is a very durable type of plastic that will be able to withstand hurricanes if you choose that option.
There are companies that sell golf ball proof windows. One example is sold by Cambridge Doors and Windows. They sell a window called the Lexan XL which is protected by a polycarbonate and is UV-resistant.