1) General Information about Plexiglass

plexiglass history type

Poly(methyl methacrylate) (PMMA) is a transparent thermoplastic often used as a lightweight or shatter-resistant alternative to glass.

Although it is not technically a type of glass, the substance has sometimes historically been called acrylic glass. Chemically, it is the synthetic polymer of methyl methacrylate.

The material was developed in 1928 in several different laboratories by many chemists such as William Chalmers, Otto Röhm and Walter Bauer and was first brought to market in 1933 by theRohm and Haas Company, under the trademark Plexiglass. It has since been sold under many different names, including Acrylite, Lucite, and Perspex.

PMMA is an economical alternative to polycarbonate (PC) when extreme strength is not necessary. Additionally, PMMA does not contain the potentially harmful bisphenol-A subunits found in polycarbonate. It is often preferred because of its moderate properties, easy handling and processing, and low cost.

Non-modified PMMA behaves in a brittle manner when loaded, especially under an impact force, and is more prone to scratching than conventional inorganic glass, but modified PMMA can achieve high scratch and impact resistance.

 

 

2) History of Plexiglass

plexiglass history plane

The first acrylic acid was created in 1843. Methacrylic acid, derived from acrylic acid, was formulated in 1865. The reaction between methacrylic acid and methanol results in the ester methyl methacrylate.

In 1877 the German chemist Wilhelm Rudolph Fittig discovered the polymerization process that turns methyl methacrylate into polymethyl methacrylate. In 1933 the brand name "Plexiglas" was patented and registered by another German chemist, Otto Röhm. 

In 1936 ICI Acrylics (now Lucite International) began the first commercially viable production of acrylic safety glass. During World War II both Allied and Axis forces used acrylic glass for submarine periscopes and aircraft windshields, canopies, and gun turrets. Incidentally, airplane pilots whose eyes were damaged by flying shards of PMMA fared much better than those injured by standard glass, demonstrating the much increased compatibility between human tissue and PMMA as compared to glass. 

Nowadays Plexiglas® brandname  is reserved by  E v o n i c   I n d u s t r i e s  as refered at her site  (www.plexiglas.de/PRODUCT/PLEXIGLAS/EN/Pages/default.aspx)

 

 

3) Plexiglass Spieces

plexiglass history eidhThere are several plexiglass qualities.

Mostly used and known cast and extruded.

Each one of them has its own features.

Cast have better properties and their price is usually higher. You may find plexiglass at the market  in sheets in thicknesses between 2mm to 200mm.

Also you may find plexiglass in round and square bars and plexiglass pipes.

 

 

 

 

4) Handling, Cutting and Joining

PMMA can be joined using cyanoacrylate cement (commonly known as superglue), with heat (welding), or by using solvents such as di- or trichloromethane to dissolve the plastic at the joint, which then fuses and sets, forming an almost invisible weld. Scratches may easily be removed by polishing or by heating the surface of the material.

Laser cutting may be used to form intricate designs from PMMA sheets. PMMA vaporizes to gaseous compounds (including its monomers) upon laser cutting, so a very clean cut is made, and cutting is performed very easily. However, the pulsed lasercutting introduces high internal stresses along the cut edge, which on exposure to solvents produce undesirable "stress-crazing" at the cut edge and several millimetres deep.

Even ammonium-based glass-cleaner and almost everything short of soap-and-water produces similar undesirable crazing, sometimes over the entire surface of the cut parts, at great distances from the stressed edge. Annealing the PMMA sheet/parts is therefore an obligatory post-processing step when intending to chemically bond lasercut parts together. This involves heating the parts in an air circulating oven from room temperature up to 90 °C (at a rate of no more than 18 degrees per hour) down to room temperature (at a rate of no more than 12 degrees per hour).

Temperature should be maintained as follows: one hour for 3 mm thickness, two hours for up to 6 mm thickness, four hours for up to 12 mm thickness, and six hours for up to 20 mm thickness. A rapid annealing cycle is reliable for thin sheets and involves placing them in a pre-heated oven to 80 °C for one hour, then removing parts from the oven and allowing to cool to room temperature.

This added time component should be factored into the whole fabrication process, and the alternative Zero-rake sawcutting technique may provide better cost-effectiveness, unless complex non-straight line edges are required. In this respect PMMA has an advantage over competing polymers such as polystyrene and polycarbonate, which require higher laser powers and give more messy and charred laser cuts.

In the majority of applications, it will not shatter. Rather, it breaks into large dull pieces. Since PMMA is softer and more easily scratched than glass, scratch-resistant coatings are often added to PMMA sheets to protect it (as well as possible other functions).

5) Plexiglass Uses

Being transparent and durable, PMMA is a versatile material and has been used in a wide range of fields and applications such as: rear-lights and instrument clusters for vehicles, appliances and lenses for glasses. 

SOURCE: All the above information and pictures are taken by wikipedia you may find them at the following link.

(http://en.wikipedia.org/wiki/Poly(methyl_methacrylate)