Lexan is a tradename (from GE) for polycarbonate whereas Plexiglass is a
tradename (can't recall whose) for acrylic.
In general, polycarbonate is a much stronger, impact resistant, tough
material that is NOT very scratch resistant unless it is hardcoated. If
polycarbonate is subjected to some alcohol cleaners and any petroleum
products it will craze (develop micro-cracks) that signifigantly weakens
its impact and flexural properties. You may have been able to find some
aircraft grade, pre-coated polycarbonate which would be terrific stuff.
Polycarbonate can be cut or machined pretty easily and can be punched or
sheared very readily.
Acrylic is a very hard plastic that WILL scratch but is more scratch
resistant than plain polycarbonate (the same hard-coats can be applied
to acrylics). Acrylic does not have the flexural strength (bendability)
but has much higher rigidity. It is NOT very impact resistant when
compared to polycarbonate but has much better chemical resistance. It
is also pretty cheap and readily available at local hardware stores.
Standard thicknesses are in usually referenced in millimeters. Sawn or
machined/routed edges should be flame-polished or fine-sanded and buffed
smooth to reduce the risk of crack propagation from the rough edges. It
tends to chip when cut and don't even think about trying to punch it.
Sorry for the pocket-protector type dissertation (probably more than you
ever wanted to know about "clear plastic") but accuracy counts from time
to time.
William Zehring wrote:
>
> At 10:07 AM 12/16/98 -0500, you wrote:
> John Blair writes:
>
> >4. Thanks to Bob N. went to a local hardware store and got new plexiglass,
> > actually something similar but more scratch resistant (cant remember it
> > name) and made new windows.
>
> Isn't that Lexan? Aircraft quality plexiglas, essentially. Scratch
> resistant.
>
> Will Zehring
--
"Entropy Happens!"
Michael D. Miles, PE Consulting Design Engineer
(503) 292-1234, FAX: (503) 292-1105, email: mdmiles@home.com
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