Phewww - just read through all 42 pages of this thread while researching Acrylic Vs Glass for my projects.
I came across a site that has interesting information about Acrylic.
http://www.hydrosight.com/glass-vs-acrylic-a-comparision
Some interesting facts (all copied from the site listed)
Acrylic glass is less dense – its density can range from 1150-1190 kg/m3. This is less than half the density of glass which ranges 2400 to 2800 kg/m3. Transportation and assembling of acrylic building materials are consequently easier and cheaper.
Acrylic glass has a higher impact strength than glass and will not shatter. Shattering is wanted by most applications where tempered (tough-ended) glass is used, e.g in automobiles. However it is not wanted for most others. Non-shattering makes Acrylic the ideal material for applications where it would induce fatal losses, like in submarine windows. Polycarbonate is also a great material that does not shatter.
Acrylic glass transmits more light than glass. Up to 92% of visible light is transmitted through acrylic. Mineral glass transmits 80-90%, depending on type of glass and manufacturer. This is especially relevant, when comparing load bearing transparent materials. These windows are mostly several centimeters thick. Load bearing mineral glass that we know of is derived from bullet-proof glass – in relation to acrylic it appears milky.
Resistance Against Chemical Attack: Acrylic is frequently used in aggressive environments. For example chlorine levels in today's swimming pools have no notable effect on acrylic. Whereas mineral glazing, that is used in the same environment deteriorates quickly. Mineral glazing for this purpose is layered and separated with plastic foil. This foil degrades quickly under these conditions.
Heat Insulation: The value of Thermal Conductivity – abbreviated ? is higher for acrylic than for glass. ? for most types of acrylic is 0.19 W/mK.
The surface of acrylic is softer and more easily scratched than mineral glass. It is advised to check acrylic cleaning guidlines in order to prevent abrasive or chemical damage. However, it is easy to polish acrylic in order to remove blemishes. Scuffed mineral glass would need to be replaced.
Two or more acrylic blocks can be bonded seamlessly to form one structure.
While there are benefits to both Plexiglas and mineral glass viewing panels depending on the application, in recent years, acrylic has surpassed mineral glass in versatility and multiple uses.
Acrylic Panels are sold under various names and brands. Some of them are:
PMMA, Polymethyl methacrylate, methyl methacrylate, Plexiglas, Perspex, Plazcryl, Acrylite, Acrylplast, Altuglas, R-Cast, Polycast, Lucite and ShinkoLite-A
however
ONE VERY DISTURBING ASPECT OF PLEXIGLASS (Acrylite in the USA)
Plexiglass(Acrylite) is owned by a German company called Evonik Degussa Gmbh.
A subsidiary of Degussa and I.G.Farben, the Degesch , produced the pest control poison Zyklon B. Zyklon B was used in the gas chambers of Auschwitz-Birkenau as the main means for mass murder. These war crimes during World War II should not be forgotten. Today the relation between Degussa and the survivors of the holocaust has improved. Degussa has come to terms with its history.
http://www.hydrosight.com/plexiglas-acrylic-made-by-rohm/
Dont know about you, but for me this is a very very god reason to never buy anything Evonik Degussa Gmbh. YMMV.