Why does transparent plastic become opaque when it breaks?

634 views

My 7yo snapped the clip off of a transparent pink plastic pen. He noticed that at the place where it broke, the transparent pink plastic became opaque white. Why does that happen (instead of it remaining transparent throughout)?

This is best illustrated by the pic I took of the [broken pen](https://imgur.com/S8rasqb).

In: Physics

13 Answers

Anonymous 0 Comments

Plastic polymers are structures of relatively ordered chains of hydrocarbons.

When you put stress on this structure, you’re breaking apart molecular bonds in those chains, causing them to form small void spaces in the structure as they’re displaced and rearranged. These voids refract light differently than the rest of the structure, causing the opacity you observe.

You are viewing 1 out of 13 answers, click here to view all answers.