Transparency of Acrylic Sheet

Beat me to it!
Polycarbonate is more scratch resistant than acrylic. I've used some as an extra layer of glazing on the fixed panes of my big double patio doors. There are double glazed anyway, but I'm hoping the extra panel and small air gap on the fixed panes will keep the house cosier in Winter.
Del

I'd say it's a toss up, depending on application. I was a little biased toward PC, because I used it to replace the side rear truck window that I busted out, while throwing firewood in my truck.

http://www.streetdirectory.com/travel_guide/203584/home_lighting/replacement_residential_skylights.html

There's some pretty tough PC out there:

http://cyrilhuzeblog.com/2010/03/26/motorcycle-windshields-material-shapes-and-sizes/

Yep, PC holds up to firewood better than acrylic, every time.

I'm sure acrylic was the best back when you were in the business...................of course, black and white television was state of the art too.

A question, wise one..............

If PC is less scratch resistant than acrylic, why not acrylic for eyeglass lenses?

Modern glasses are typically supported by pads on the bridge of the nose and by temple arms (sides) placed over the ears. CR-39 lenses are the most common plastic lenses due to their low weight, high scratch resistance, low dispersion, and low transparency to ultraviolet and infrared radiation.^{[citation needed]} Polycarbonate and Trivex lenses are the lightest and most shatter-resistant, making them the best for impact protection.^[1]

http://en.wikipedia.org/wiki/Glasses

The best of both worlds:

http://www.dow.com/additives/news/2012/20120308a.htm

Well sonny,

First "CR-39 should not be confused with polycarbonate". From your citation.

I never said, "PC is less scratch resistant than acrylic,". You put words in my mouth there.

PC is used in glasses because it is tougher, as you suggest.

It IS NOT a better transmitter of light, which was the question, If I remember correctly.

CR-39 was developed for B-17 bomber fuel tank reinforcement. I was not around for that. Even I am not that old.

Just admit that you are wrong, and the old man is RIGHT, again!

Why does being right all the time make you so grumpy?

It's in my genes.

Compared with the following price:

1. Acrylics with Non scratch coatings.

2. Polycarbonate

Which one is cheaper?

Also, if for cutting, which one is easier?

Thanks

My design window size will be similar as 3x4 foot and the location will not be very prone to wind.

May I use the information kiosks as a guideline? Could you help me to check the thickness of acrylic sheet?

Thanks

My kiosks windows are all vertical, so there's no bowing. I use 1/8 inch thick Uv stabilized acrylic.

For horizontal mounting I'd go with 1/4 inch or thicker. Or, Domed Skylights, but they are expensive.

• Installing Skylights|DoItYourself.com
• Pros and Cons of The Acrylic Skylight
• Choosing a Skylight

In any case, you do not want water to pool on the skylight. so don't mount it on the horizontal without some pitch.

Anyone has design data for an acrylic pane or PC pane:

Pane size vs thickness vs wind load.

One more thing, is acrylic pane easier to creep for long term load than that of PC?

OK, acrylic ie Perspex, score and crack with the right Stanley blade and a rabbits foot, but a fine finish saw at a low angle and go steady, or order at the right size, polycarb, there is not score and crack option, same saw technique. I have heard that both pc and acrylic yellow and don't yellow. Look at pet, as mentioned, harder to break than both, non yellowing, and at 3mm, can be bent cold, and doesn't form a white line.

But fixing. Don't go round with a drill and screw it down every 100mm, unless your temperature never fluctuates. It will crack when things warm up or cool down. Best way is allow some expansion room, and hang it from the top, so it stays vertical. the bus shelters may be done like this, with a gasket around. Glue a strip say 15mm deep on the top, hook it over a similar strip on your window, trap it with a frame. Thickness, 3 or 5mm are the standard, 5mm would kill it 3mm would do it.

cnc jim

Agreed, GA.

You may want to look UV PETG. It clarity is close to acrylic and is more durable.

Polycarbonate yellows as it ages, esp. due to the UV in sunlight. Acrylic does not.

The initial clarity is about the same. Polycarbonate is tougher, and less likely to chip, but it is also softer and more prone to scratching - though you can get both coated with a thin anti-scratch layer.

Here's a more thorough comparison:

http://www.hydrosight.com/technology/polycarbonate_vs_acrylic.php

Polycarbonate yellows as it ages, esp. due to the UV in sunlight. Acrylic does not.I will accept that you have experience in this and are correctly remembering it as so. In my experience the opposite is true. UNLESS you had the uv protected Acrylic and i didn't. And i had uv protected PC where you didn't. I don't know which part of the world the OP is in but here in OZ the UV is extreme and unprotected sheeting lasts no more than a couple of years.

I find it interesting that there are 2 materials presently under consideration as alternatives to glass and each material has at least one "good answer" vote. I vote for polycarbonate because of its superior impact resistance and resistance to stress cracking.

The piece of PC I bought to replace my truck window, is guaranteed against yellowing or cracking, for 10 years. Throwing big chunks of wood at it though, would probably void the warranty.

When I found that motorcycle windshields were made from PC, I was convinced. Those see a lot of sunlight.

_{Don't tell Lyn he's wrong.}

And motorcycle helmets (the cheaper kind) are made from Polycarbonate. Not from acrylic. The visors are all made out of polycarbonate, specifically lexan They scratch, but don't break. Shards from a shattering face shield would be bad.

I don't like acrylic if I have to drill a hole and screw it onto something. It always breaks out. Otherwise, as a window pane drop in replacement, I have used both, and they both seem to work.

They all scratch.

It'll be interesting to see how the Dow anti-scratch additive works out.

You're right. They all scratch.

Get some of this. I believe the coating is considered to be an acrylic. Everyone gets to be right, and you get the best product available.

http://www.usplastic.com/catalog/item.aspx?itemid=23753&catid=704

One important point that needs to be considered:

• If one throws something hard and heavy at glass it will break. This feature may be beneficial in order to form an easy escape route in the unlikely event of a fire developing within the building.

...which is why glass forms part of the Building Regulations for domestic premises in the UK.

Good point PW! I'd hate to see the guy fit his house with indestructible windows, and not be able to get out in a fire.

I find it hard to imagine somebody trying to escape from a house fire through a skylight...