| Topic: |
Science > Physics |
| User: |
"Mark Fergerson" |
| Date: |
04 Feb 2005 02:16:14 PM |
| Object: |
Stupid question; telling plexi from polycarb |
I ought to know this, but memory fades and Google is a flood I can't
find my teaspoon-full of info in..
I place a sheet of transparent plastic between crossed polarizers and
_don't_ see colors; which am I looking at? I wear "high-index polycarb"
eyeglasses and they show colors, but neither of two sheets of what I
thought were different materials (one plexi, the other polycarb) do.
Any other quick 'n' dirty ways to tell one from the other, including
destructive tests (in a typical home shop, no lab available)?
Mark L. Fergerson
.
|
|
| User: "Franz Heymann" |
|
| Title: Re: Stupid question; telling plexi from polycarb |
04 Feb 2005 04:17:00 PM |
|
|
"Mark Fergerson" <nunya@biz.ness> wrote in message
news:hKQMd.9235$6u.1990@fed1read02...
I ought to know this, but memory fades and Google is a flood I
can't
find my teaspoon-full of info in..
I place a sheet of transparent plastic between crossed polarizers
and
_don't_ see colors; which am I looking at? I wear "high-index
polycarb"
eyeglasses and they show colors, but neither of two sheets of what I
thought were different materials (one plexi, the other polycarb) do.
In the late 1940's a friend of mine used perspex (plexiglas) models to
investigate strains in civil engineering structures by studying the
colours of which you speak. I think you have to put the material
under stress to see colour bands..
Any other quick 'n' dirty ways to tell one from the other,
including
destructive tests (in a typical home shop, no lab available)?
Mark L. Fergerson
.
|
|
|
| User: "Mark Fergerson" |
|
| Title: Re: Stupid question; telling plexi from polycarb |
05 Feb 2005 08:54:46 AM |
|
|
Franz Heymann wrote:
"Mark Fergerson" <nunya@biz.ness> wrote in message
news:hKQMd.9235$6u.1990@fed1read02...
I place a sheet of transparent plastic between crossed polarizers
and _don't_ see colors; which am I looking at? I wear "high-index
polycarb"eyeglasses and they show colors, but neither of two sheets of what I
thought were different materials (one plexi, the other polycarb) do.
In the late 1940's a friend of mine used perspex (plexiglas) models to
investigate strains in civil engineering structures by studying the
colours of which you speak. I think you have to put the material
under stress to see colour bands..
Both sheets were clamped in a bench vise for convenience (I don't
have three hands), but I suppose stresses parallel to line of sight
don't make bands? I'll carefully set a small bench anvil on one top
corner and see if that works.
This is weird; one lens of my glasses shows gently curved bands, the
other sharp jagged ones reminiscent of those of crystals.
Mark L. Fergerson
.
|
|
|
|
|
| User: "Monk Kiy" |
|
| Title: Re: Stupid question; telling plexi from polycarb |
04 Feb 2005 02:55:56 PM |
|
|
"Mark Fergerson" <nunya@biz.ness> wrote in message
news:hKQMd.9235$6u.1990@fed1read02...
I ought to know this, but memory fades and Google is a flood I can't
find my teaspoon-full of info in..
I place a sheet of transparent plastic between crossed polarizers and
_don't_ see colors; which am I looking at? I wear "high-index polycarb"
eyeglasses and they show colors, but neither of two sheets of what I
thought were different materials (one plexi, the other polycarb) do.
Any other quick 'n' dirty ways to tell one from the other, including
destructive tests (in a typical home shop, no lab available)?
Mark L. Fergerson
the sheets are more uniform, and thinner than your glasses which have been
heat stressed.
poly carb is harder than plexi try scratch testing
.
|
|
|
|
| User: "Uncle Al" |
|
| Title: Re: Stupid question; telling plexi from polycarb |
04 Feb 2005 03:25:00 PM |
|
|
Mark Fergerson wrote:
I ought to know this, but memory fades and Google is a flood I can't
find my teaspoon-full of info in..
I place a sheet of transparent plastic between crossed polarizers and
_don't_ see colors; which am I looking at? I wear "high-index polycarb"
eyeglasses and they show colors, but neither of two sheets of what I
thought were different materials (one plexi, the other polycarb) do.
Any other quick 'n' dirty ways to tell one from the other, including
destructive tests (in a typical home shop, no lab available)?
Look at a sheet at a high angle. Plexiglas is not nearly as
dispersive as polycarb. You'll see a rainbow with polycarb.
Polarization has nothing to do with it. Polycarb has a much higher
index of refraction, so look at critical angle. Plexiglas smells of
acrylic monomer if you abrade it with sandpaper, snap off a piece, or
touch it with a hot wire. Polycarb smells like phenolics if you
pyrolyze it.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
|
|
|
| User: "tj Frazir" |
|
| Title: Re: Stupid question; telling plexi from polycarb |
04 Feb 2005 05:09:51 PM |
|
|
Burn a pice ,,smell like styrofoam plastic or hair ?
fire is for shure.
.
|
|
|
|
|
| User: "tj Frazir" |
|
| Title: Re: Stupid question; telling plexi from polycarb burn it |
04 Feb 2005 05:16:25 PM |
|
|
quick and dirty ,,fire up a corner and smell it.
Hair ,,plastic ,,I bet if I lit a joint you could small waht kind.
Nylon , hair , then plasics ,
Burn a pice and smell it is the quick dirty method.
Idonno what the ***** uncle stupid was tinking.
Uncle unifickle is a chemist but was absent on burn day .
.
|
|
|
|
|
Related Articles |
|
|
