Team K.a.L.M.

**Eventorizon** · 24th March 2015, 21:40

Get a small piece and hit it with a hammer. If it deforms without breaking, it will be near HDPE, if it shatters its closer to LDPE and if it in between it may have some PET in it too... note: this is all coming from a handout I got in Materials for Designers at uni so its pretty vague :-P

**Ellis** · 24th March 2015, 23:12

Would be surprised if LDPE is the more shatter prone. Why would lower density be more brittle, surely it'd be even softer and more malleable than a high density variant?

**overkill** · 24th March 2015, 23:42

I find that stiffness & brittleness increases as the density goes down. UHMW-PE is softer than HDPE, which is softer than LDPE; sometimes there is very little difference between them. Manufacturers often have variations within each type IE I have some UMHW with a higher melting point and another which has more wear resistance.

EDIT: I found this interesting comparison article: http://en.wikipedia.org/wiki/Polyeth...ene_.28HDPE.29 it makes linear LDPE sound particularly interesting.

**Niels - Team K.a.L.M.** · 25th March 2015, 02:17

I swung a 4kg hammer at the stuff and it flexes a little but didn't deform.

From what i know, LDPE is easier to break than HDPE.

But yeah, it's more malleable that regular hdpe and therefore screws will get ripped out easier.
It's because I have tons of it that I use it.

**cavecrusher** · 25th March 2015, 06:12

Originally Posted by Eventorizon

Hit it with a hammer.

very scientific :P

Then again, that's how a izod/charpy notch test works...

**Eventorizon** · 25th March 2015, 06:42

Originally Posted by Ellis

Would be surprised if LDPE is the more shatter prone. Why would lower density be more brittle, surely it'd be even softer and more malleable than a high density variant?

Those chopping boards you used on Tormenta 1 were LDPE, need I say more? ;-) LDPE has shorter polymer chains and as a result breaks more easily as there are less crosses and linkages. (I hope I remembered that right)