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[…] Hat-tip: Overlawyered […]

Polycarbonate is the next auto window material. The NHTSA has approved its use for non-windshield purposes as long as it meets the same requirements as the current tempered glass. It is expensive, and there are questions about its ability not become too scratched and hazy, but it has some marvelous properties. It maybe that door handles change formed into it, it can used to create an entire car roof, with mult-c0lors on the same molded piece, and it is a couple hundred times stronger than tempered glass: rollover tests have shown it to be unbreakable. It deforms, but doesn’t break. So nothing will escape the car.

Of course, nothing will escape the car if after the crash it is on fire, or sinking into the river. Nothing will get in without tools if the doors are locked or deformation prevents opening. Impossible for a man with sledgehammer to break, it is unlikely you’ll have anything in the car to break it. And perhaps your responding fire department auto extrication unit might not either — at a recent auto extrication course the instructors told us it is very difficult to cut — we might have to drill two holes, run a cable through them, and yank the window out with a winch or another vehicle. This will, of course, take time to call the FD, have them arrive, and get out the required tools. If the car is filling with smoke— well, the lawyers of the relatives can always sue the auto manufacturer for using polycarbonate instead of tempered glass.

My father, chief engineer of the British subsidiary of GM, used to joke (in the 1960s) that there were fewer complaints regarding laminated windshields compared with toughened glass windshields because people with laminated windshields didn’t live to tell the tale. At that time, all UK cars had toughened glass windshields; I don’t know the situation now. Toughened glass should be safer when it shatters, since it crumbles, whereas laminated glass can cut you to pieces if any of your body passes through it. This was of more significant importance before seat belts. The disadvantage of toughened glass is that when it breaks, the whole sheet cracks into small pieces that become difficult to see through.

Since toughened glass should be safer (indeed, it used to be known as “safety glass”) the law suit referenced is completely mysterious to me.

As for polycarbonate, I work with it often, and cannot imagine how it could be practical in automobiles, because of its vulnerability to scratches. Think of a 5-gallon plastic water bottle, all scuffed and “misty” looking. That’s polycarbonate.

“As for polycarbonate, I work with it often, and cannot imagine how it could be practical in automobiles, because of its vulnerability to scratches. Think of a 5-gallon plastic water bottle, all scuffed and “misty” looking. That’s polycarbonate.”

This is one of the issues slowing down its use, but the companies pursuing this think it can be tamed. One solution is to coat the polycarbonate with a “glass-like” hard surface to prevent scratching.

Here is one article discussing this: http://www.allbusiness.com/manufacturing/nonmetallic-mineral-product-mfg/6342892-1.html

I appreciate reading the engineers’ points of view, instead of the lawyers’. That is refreshing. However, “it is a couple hundred times stronger than tempered glass…” ? I doubt that. Maybe you are talking about ductility, not tensile strength. See, glass is damn strong, which is why fiberglass composite is such a good material. Glass is “brittle” though, and that’s what makes it easy to bust via a sharp crack.

BTW, the property that describes the problem with the polymers is that of “hardness”. Glass is nice and hard, which explains why one can clean it with a razorblade, yet not scrape plexiglass in this way.

What would be wrong with putting the polycarbonate in mounting frames that are made to a spec. where the window will pop out (either way) with a certain force applied at a certain point (kinda but not exactly like the deal with city bus windows)? Busting through the glass during a fire is doable, of course, but not as easy as one may think (it may take a couple of shots, even with a brick – no kidding – try it (on your old clunker, before you turn it in for $4,500 😉 )

Whatever you do, the lawyers are gonna sue somebody anyway. Going back to Mr. Olson’s post, then, I think suing the wife is the best bet. Anyone who’s anyone knows about women drivers. It’s an open-and-shut case. So, will be the subsequent divorce. She should have known better than to drive directly into a funnel cloud, the stupid broad, and, she should have set the mini-van down on top of a barn, like most of the mid-westerners do (she may have been a non-mid-westerner, maybe one of them yankee drug dealers).

Even so, those Godless tornadoes are to blame also. They need to learn the RULE OF LAWYERS. Court finds against the defendant with prejudice – defendant must cease and desist from all convective activity for 6 months!

Oh, wait, it happened in Maryland?? Huh? What was that tornado doing there to begin with? (even more reason to sue)

Last time I checked, sunlight degrades polycarbonite. I know of at least two occasions that bullet resistant windows failed, because the people operating the armoured cars didn’t replace the windows at the correct times.

Let’s face it, no matter what you do, some lawyer is going to claim that you didn’t do enough. If you build a car that protects its passengers from a nuclear blast 15 feet away, so that all they get is a few bumps and bruises, you can bet you will be sued for the bumps and bruises.

Quibbles:

“Busting through the glass during a fire is doable, of course, but not as easy as one may think (it may take a couple of shots, even with a brick”
I dunno, tempered glass, as used in US auto side windows, seems relatively easy to break to me. I’ve done it several times (auto extrication training), and burglars do it with great regularity. It only require the force be exerted on a very small area, preferably in one corner, but it doesn’t take all that much force. A small, spring loaded center punch, or even a regular punch or similarly shaped object will do (an antenna for instance). A Fireman’s axe of course works wonders!!, but will bounce right off of polycarbonate.

Jim: UV resistance is the other issue with polycarbonate — “hardness,” as Dave noted, being the other — but at least one proposed solution type is the same for both — two small layers of other materials, one for hardness, one for UV absorbing/reflective material.

There are polycarbonate car parts already. They’re here, and as the UV and hardness problems get worked out, they will expand, because the material has a lot of advantages over both current glass and metal.

The problem is, no matter how many advantages it brings, automakers will be sued for any disadvantages in isolation from any trade-offs. Only the alleged defect will be considered, as in the case of the three girls who rolled their Explorer…