The aircraft windshield on smaller aircraft is usually made from polycarbonate, a type of plastic, while pressurized airplanes use a sandwich of plastic and glass layers, called a laminate, up to 20mm thick. This is necessary to absorb the impact of birds, insects and other debris that may collide with the windshield as the airplane flies at close to the speed of sound

AIRCRAFT WINDSHIELD AND WINDOW CARE AND MAINTENANCE
You can keep your aircraft windshield and windows looking and performing like new by using the proper care products and techniques, and by understanding a little about the material you are working with
First, most aircraft windows are acrylic plastic (as opposed to “Lexan” or polycarbonate), and acrylic plastic is scratchable. Proper care involves preventing scratches that are preventable and properly taking care of those that are not.
When cleaning a window, always remove as much abrasive dirt as possible without touching the surface. Ideally this would involve flushing the surface with water and allowing the accumulated bug residue to soak, possibly with a little dish washing liquid added to the water. If a little rubbing is needed, do it lightly with your bare hand. After a final flushing with more water and carefully drying with a clean soft cloth, use a good grade cleaner/polish intended for acrylic windows, following the manufacturers directions.
We need to step back here and take a look at cleaner/polishes. Everybody seems to have a favorite, from great and proper to poor and very dangerous. The good ones, at least those that are safe to use on acrylic plastics, tend to be the commercial ones, intended to be used on this specific material. The bad ones, including the very dangerous, tend to be materials never intended to be used as an aircraft window cleaner/polish, such as lass cleaners and furniture polish. Glass cleaners invariably contain ammonia, a killer of acrylics. DO NOT use anything containing ammonia on acrylic plastics. It will cause crazing (thousands of microscopic cracks) in short order. Furniture polish seems to be safer, but its long term use is undocumented and reports indicate it builds up and produces smears that are hard to polish off. Something to consider about furniture polish – it is intended to be used indoors, not outdoors, and on furniture, not aircraft windows. Furthermore, it’s not much less expensive than many aircraft window products.