According to my science crime buster notes from scinece olympiad
HDPE has a density of .95
LDPE has a density of .92
thus both of these polymers would float in water.
To differenciate between the two you would use 46% Isopropyl Alcohol. If it floats it would be LDPE. If it sinks it would be HDPE.
source:
http://soinc.org/sites/default/files/uploaded_files/crimebusters/PolymersEnclosure.pdf
Chris D
--- On Thu, 10/30/08, Peter Kearney <peterkearney_at_sympatico.ca> wrote:
From: Peter Kearney <peterkearney_at_sympatico.ca>
Subject: [Indoor_Construction] Storing Rubber
To: Indoor_Construction_at_yahoogroups.com
Date: Thursday, October 30, 2008, 12:19 AM
I've stored my rubber for years in ziploc freezer bags inside of a
lightproof container in my basement, with no ill effects.
If I'm not mistaken, what you want are high density polyethylene (HDPE)
freezer bags as opposed to the cheaper low density polyethylene (LDPE)
standard sandwich bags .
HDPE bags are denser than water (I think?) and will sink and the LDPE bags
are slightly less dense than water and will float.
The freezer bags contain no BPA, DEHA or other plasticizers that can outgas
or leach into the rubber.
I'm not sure if Bill Henderson is still on this list, but he was my indoor
model mentor and an expert in all things chemical/materials. He told me all
about it once, but I've completely forgotten what exactly he said (hey, it
was 20 years ago!) but I do know that he recommended the freezer bags, and
it works.
-Peter Kearney
Received on Sat Nov 01 2008 - 08:31:12 CET