Re: Plexiglas or whatever

[protek@shreve.net]

Ray,
    I think you are right on all counts.  Lexan is a trade name for a
certain polycarbonate.  They are related to acrylic plastic.  It is used
for bullet proof windows.  I know of people using it for viewports, but
here is my reasoning why not to use it;  I know of no studies of this
material used in viewport designs.  It seems logical, but I just don't know
of any solid figures on it.  It is a lot more durable than acrylic and it
is far more shatter resistant.  I have heard though that it bends more
under stress when used in sub windows.  My friend Harold from Longview
Texas used it in his sub.  He has taken it down to 100 feet before and his
windows are slightly larger than mine.  He used 0.5 inch thick Lexan.
Personally, I think this is too thin for any window at 100 feet.  He
reasoned that Lexan is "250 times stronger" than plexiglass so it did not
need to be thicker.  I don't agree, but he has made 100+ dives, some to
better than 100 feet.  I can see why people want to use it for sub windows.
 However, the acrylic figures are there and it is tried and proven.

Gary


At 11:17 AM 3/31/99 -0800, you wrote:
>Hi,
>
>>From what I can remember is:
>
>1. Lexan is a trade name for one manufacture's polycarbonate.
>
>2. Polycarbonates are simular to acrylic but not the same thing. 
>   Polycarbonates are tougher but more brittle than acrylic. Occasionally
>   a piece of polycarbonate being cut would catch in a saw and kick back
>   causing some nasty cuts. Vicious stuff to work with even with carbide
tipped
>   blades.
>
>3. Because polycarbonate is tougher it is the material used for bullet
>   proof (resistant really) glass.
>
>4. Can polycarbonates for used for view ports? I don't know. I would consult
>   the viewport book.
>
>Regards,
>Ray
>
>> Okay, here's part  what I didn't know.
>> 
>> >David,
>> >    The reason I use, and suggest the use of, acrylic plastics for windows
>> >can easily be summed up. ....The main contender for replacement is
>> >polycarbonate (Lexan)....
>> 
>> ...I just always thought of all this stuff as the same -- "Clear Plastic"
>> -- And the different names being trademarks. Duh. I'm not even sure, but I
>> think I recall the guy at the window place saying the stuff he was putting
>> in my windowframes was "lexan." So... this is apparently polycarbonate
>> which is not what you're using. Is there a common brand name of acrylic
>> thrown around just as carelessly? Is "plexi-glass" (further bastardized by
>> the careless "nucular" crowd into "flexi-glass") something else entirely?
>> 
>> If what I've got in my trailer is polycarbonate (or, to be on topic, if I
>> use a spare hunk of it in an ambient sub or glass-bottomed boat)... can I
>> polish it in a similar way?
>> 
>> 
>> ---------
>> David
>> buchner@wcta.net
>> http://customer.wcta.net/buchner
>> Osage MN USA
>> 
>> 
>
>
>