Originally Posted by Voyager
hey guys im still learning some things about racing but i was browsing a site and saw some things about lexan windows. how are they better than normal windows? i figure they probably dont shatter like glass. but is it lighter. and why dont people use them on normal street cars?
You are correct. Lexan does not shatter.
Lexan has a low modulus of elasticity and is much less stiff than glass. For the equivalent weight of lexan and glass, glass will be much stiffer.
However, it has a much higher impact strength than glass.
People don't use them on normal street cars because of a few reasons:
1) As mentioned before, it's nearly impossible to "break" lexan, which means that traditional methods of emergency egress/ingress are ineffective.
2) Lexan has a very low hardness. This means that it will scratch very easily, much like the surface of an ipod. Over time, road dust, rocks, etc will turn lexan into a hazy mess. There is technology available to "coat" lexan with a high-hardness film, but this coating is not ready for mass production.
3) Lexan degrades in ultraviolet. A glass auto window may last for a thousand years in the sun without any degradation. A lexan window will yellow and become brittle in less than a decade. Films/coatings can reduce this effect but the UV resistance will never be as good as glass.
4) Lexan does not have the dimensional/temperature stability that glass has. Glass can easily withstand temperatures up to 400+ degrees without losing any of its physical properties. Lexan loses some of its physical properties at temperatures as low as 200 degrees fahrenheit, becoming weaker and/or more flexible.