How can a thin layer of glass have the flexibility of plastic?


Some context: I’m in the market for baby bottles. Some manufacturers produce bottles which they state are plastic on the outside and glass on the inside, so the milk only touches glass when it’s inside the bottle. They explain it as a thin layer of glass that somehow binds to the outer plastic. And somehow it’s also unbreakable or shatter-proof.

The bottle itself has the flexibility of regular plastic, which is very odd to me, I usually expect anything made of glass to be completely stiff.

How is this possible?

Also… is there a way for me to know or somehow check if the inside of the bottle really is glass?

In: 0


Some glasses has a bit of flexibility like gorilla glass used on phone screen.

Still, it’s not much compare to what thin flimsy plastic can have.

Maybe that bottle has thick rigid plastic to match the flexibility?

I don’t think the manufacturer can get away with false ad so I assume it’s true… One way to test it is to pour acetone inside and see if internal surface melt. But there’s a risk that the vapor of it damaging any exposed plastic such as screw of the bottle.

Also there’s a thing called flexiglass that is actually acrylic resin(plastic) and people think it’s a glass. But it’s not food safe so I don’t think it’s the case.

It’s called Invinci-glass, which is basically made by spraying the inside of the plastic bottle with aerosolized glass. It’s an extremely thin coating, but enough to provide a 100% glass interior. The thinner glass is, the more flexible it gets without cracking, and this stuff is *extremely* thin.

When a material is bent, part of it is compressed and part of it stretches out. If I take a sheet of paper and bend it so the “bump” is facing away from me, it means that the side of the paper close to me is being compressed, or smashed against itself on a microscopic level. On the other side, it’s stretching. Now imagine a piece of paper ten times as thick. The paper on each side has to stretch or compress a lot more on the thick sheet than on the thin sheet to create an equal sized bend. If we had a sheet with zero thickness, it would not have to stretch or compress on either side and could be bent into a super tiny circle without breaking. This isn’t possible, but as we approach zero thickness, we stretch the material less and less.

Some materials stretch or compress better than others without breaking. A thick piece of rubber can bend without breaking because the material can stretch a lot on the outside of the curve before ripping. Glass can’t handle this as a material, so it’s usually pretty fragile when it’s thick. When we make the sheet of glass super thin, each side of the bend has to deform very little and we don’t get the glass to its breaking point because it’s barely stretching or compressing