Cost of acrylic per sq ft.

John,

You seem to be getting a very good buy. A square foot of 0.118" thick acrylic weighs about

0.72 lbs. (June 14, 2004 issue) lists GP acrylic as selling at $0.96-1.01/lb. The old "rule-of-thumb" is that a processing will double the price paid for the resin. At $1.00/lb resin cost, you could expect to pay around $1.44 per sq. foot of 0.118" sheet.

Regards,

Ernie

Thanks Ernie I suppose the lower cost could be due to the sheet I'm buying is extruded vs. cell cast. I understand that they add something to the PMMA to make it melt better for extrusion and fab work. Extruded acrylic is supposed to be the economy version, but it still seems very clear, UV/weather resistant and distortion free for my purposes.

Thanks, John

The starting monomer for both casting and extrusion resin is methyl methacrylate (MMA).

A typical casting process starts with 99.5+% MMA and partially polymerizes it to something like 25% polymer in MMA. The polymerization is stopped, and the polymer solution is later polymerized either between plates (cell cast) or between continuous belts (continuous cast). The cell casting process involves lot of labor, and the belt process requires very expensive equipment that produces very few pounds of polymer per $ of investment. This is why cast sheet is expensive.

To get from MMA monomer to extruded sheet also involves at least two, usually three steps. In the most common process of today: 1. MMA plus about 5% of a comonomer, usually ethyl acrylate, are partially polymerized, similar to cast sheet, 2. then the polymerization is finished in extruder like reactor; the polymer from the extruder is small "cubes". As mentioned above, the "cubes" sell for around $1/lb. 3. Typically, a different company buys the cubes from the resin manufacturer and extrudes it into sheet. The productivity rates in these three steps are much much higher than in the cast sheet, thus the selling price of the sheet is lower.

In my opinion, cell cast used to be the best quality, with continuous cast a close second, but for many applications extruded sheet can be a very good choice.

Good luck,

Ernie

polymerized,

Thanks for sharing that. The margins must be very slim. I was beginning to think they misquoted the price, but now I have the material in hand. Thanks again, John