Acrylic Polycarbonate Plexiglas Lexan, what to use

[Bender]

Acrylic, Polycarbonate, Plexiglas, Lexan; they are all interchangeable terms in most peoples vocabulary. Getting the terminology correct could save your project from becoming a disaster.

Of all four materials listed above there are really only two plastics involved, polycarbonate and acrylic. Lexan is General Electric's trade name for Polycarbonate and acrylics trade name is Plexiglas.

Acrylic = Plexiglas
Polycarbonate = Lexan

Why does all this matter? In two words I would answer "Impact Resistance." If you’re planning any sort of project involving one of these two transparent materials you will want to know the one major drawback acrylic has to offer. Impact resistance is the key. If you want your project to hold up for any length of time under normal use, polycarbonate is the material of choice. Acrylic has a very low impact resistance and is prone to stress fracturing. Polycarbonate on the other hand has impact resistance 30x that of acrylic. Polycarbonate is also a harder material than acrylic making it less prone to scratching.

Proof:

Acrylic / Plexiglas Extruded

Impact Strength 0.4 ft lbs / in
Hardness Rockwell M: 93

Polycarbonate / Lexan

Impact Strength 12 ft lbs / in
Hardness Rockwell R: 118

These numbers are for the most common types of each material. Higher grades of each material are available but can cost quite a bit more. Even with high grade acrylic and polycarbonate the trend continues. Polycarbonate beats out acrylic in all the areas that make a difference for our uses.

What can acrylic be used for? Window mods are probably ok as long as you’re not playing football with your case. ITX cases, mATX might be pushing it depending on design. For standard ATX acrylic is a very bad choice. Even if you don’t kick your case, micro fracturing can occur around high stress areas. Polycarbonate is more expensive than but the costs far outweigh the disadvantages of acrylic.

Here is a price comparison of what I paid for each material.

Home Depot 24x48 sheet of .25” thick acrylic $30

McMastercarr 24x48 sheet of .25” thick polycarbonate $45
UPS ground for 2 sheets was only $11.75!

Where can you purchase these materials?
Home depot usually stocks acrylic but polycarbonate can be scarce
www.mcmastercarr.com is an excellent choice for either. They even stock bullet resistant polycarbonate sheets!

I hope this is of some use in your future projects

~Bender

 

[tweaker]

THANK YOU! you saved me some time had I bought the cheapie stuff. I bought the better and it was easier to work with and allowed better moddig with no mess ups

Thanx again!

tweaker

 

[four4875]

i bought some cheap plexi once.... it cracked when i was carryin it home...

and to the point: thanks. i was wondering.. WTF?? i've never heard polycarbonate before. (seen mentioned in another thread) thanks for the info, and is this a new sticky?

 

[Paxmax]

Polycarbonate under stress

Just a short addition: Don't put polycarbonates(i.e. lexan, makrolon, pc) under constant stress, microfractures will emerge under time.
If you bolt two peices together make sure that the peice which the screw is going through has good support close-up around the hole!
If you fail that and you get a "microbend" under the screwhead the polycarbonate will crack. PC is very shockresistant but has problems with static load.

 

[Koopa_Fett]

I know it's a lot of money, but I think my pc needs a bullet-proof window.

Thanks for the info, I'm cutting out a window very soon.

 

[Captain Slug]

Polycarbonate is also preferable for appliations where heavy tooling is a requirement. It's higher operating temperature makes it less prone to bubbling, melting, and warping. It is also non-toxic (where-as Acrylic melts quickly and can lech toxic fumes).

On the basis of personal safety alone I only recommend that people use Polycarbonate. Acrylic is meant for professional applications where optical clarity, heat-warping, abrasion resistance, and low cost are required. Such as display cases, Green houses, and office building windows.

And just to be clear, the Bullet-proof properties of Lexan are dependant upon the grade and THICKNESS of the sheets used.

 

[Imacrzyprsn]

Sweet deal, i just picked up a pretty big roll of Lexan! =).

 

[Caffinehog]

I put some polycarbonate in a blowtorch flame once. It doesn't melt. It only kind of burns, too.
What did I have polycarbonate for? I took a polycarbonate tube, roughed up the outside, put some EL wire in the middle, and created a light-up lightsaber that you can actually fight with. Not for me... for a friend of course...

 

[Ubik]

Hmm, where can I find colored transparent acrylic? I don't need big sheets, I'm just undertaking a little side project for the side of my case... All I need is about a square foot each of transparent red and transparent green (I only need it that big so I have some leeway in case I screw up on the cutting).

 

[Cyberwiz01]

For a site that focuses just on plastics
go to
www.usplastics.com for plexi, lexan, or whatever other plastic you want.
The prices seem decent too.

 

[GoldenTiger]

Are you saying that buying a case like this:

http://www.svcompucycle.com/clearaccasat.html

would be a bad idea as it would break and crack just from normal use (I don't move my computers ever, but you're saying something might happen even just with it sitting there?)?

 

[Audioaficionado]

Not bad for ~$70. Get a pexi case for the PS and do the window mod on your hard drives, you could see everything.

 

[bkn_1971]

looks great but it is also just waiting to crack,heck ups it and it will probably arive cracked hahahahahah

 

[NiteSmoker17]

I found a place where you can get colored sheets. http://www.copeplastics.com

 

[RonnieG]

I've got some unlabelled sheets around here. How do I tell if it's acrylic or polycarbonate???

 

[onewecallgod]

i got a sheet of "crystallite" for 10$ at homedepot. 2 feet by 1.5 feet. its about 1/4 inch thick. is this lexan or plexiglass?

 

[RonnieG]

*bump*

 

[krakhead]

i ran acrossed a site that had uv reactive plexi. cant remeber the link. ill try to find it

 

[Captain Slug]

i got a sheet of "crystallite" for 10$ at homedepot. 2 feet by 1.5 feet. its about 1/4 inch thick. is this lexan or plexiglass?

Neither. It's acrylite with is rather fragile. It's material properties are actually worse than glass.

 

[Captain Slug]

I've got some unlabelled sheets around here. How do I tell if it's acrylic or polycarbonate???

If the protective coating doesn't say LEXAN or GE or Rhinex, it's propably arcylic.
The easiest way to tell is to run your keys along the edge. Polycarbonate is fairly easy to scratch but has far better heat resistance and toolng properties.