Polymethyl methacrylate was developed and brought to market maturity in the first half of the 20th century by the German chemist Walter Bauer, among others. As a typical thermoplastic, PMMA can also be molded into almost any shape under the influence of heat and then hardened again. This results in a wide variety of very elegant shapes for a wide range of applications.

PMMA has a comparatively high hardness and impact strength and is therefore often used as a shatterproof alternative to conventional mineral glass.

Polycarbonate bears a certain resemblance to PMMA. This is also a transparent thermoplastic, but it is much softer and thus has a completely different range of applications.

As with many thermoplastics, the properties of acrylic glass can also be specifically varied during the manufacturing process and adapted to the intended use. As a result, many properties cannot be precisely specified for Plexiglas. The following list, however, provides a reliable listing of the most important values. PMMA is

• lighter than mineral glass,
• resistant to alcohol,
• weather and UV resistant, and
• very impact resistant.

Irrespective of this, products for special applications can deviate specifically from these values and have other properties.

The physical properties of PMMA make it well suited for use in Exterior

Polymethyl methacrylate is one of the plastics that are ideal for outdoor use due to their physical, mechanical and chemical properties. For example, acrylic is highly resistant to weathering and absorbs UV radiation. The refractive index and other optical properties are comparable to or exceed those of conventional mineral glass. At the same time, cast PMMA is optically of significantly higher quality than extruded polymethyl methacrylate.

PMMA is resistant to gasoline and oils as well as a wide range of acids and alkalis. Benzene, ethanol and acetone, on the other hand, cause stress corrosion cracking and destroy PMMA on contact.

A high resistance to fracture

A density of 1.19 g/cm³ and very high impact strength make PMMA an ideal and superior replacement for mineral glass. With a 30 times greater impact resistance, for example, it can be regarded as virtually unbreakable at a significantly lower weight. The lower scratch resistance of the plastic compared with mineral glass can be significantly increased by special surface coatings.

In addition, polymethyl methacrylate is easier to work with than mineral glass. It is easy to drill, mill, saw and glue.

The thermal properties favor the special flexibility of PMMA

As a thermoplastic, polymethylmethacrylate can be reversibly deformed at temperatures above 100 °C. Between -40 °C and 80 °C, acrylic is dimensionally stable, but exhibits very high thermal expansion. On average, it is 1.5 per mil, but this can quickly lead to material shrinkage of 5 to 10 centimeters in the case of a large patio roof. One of the most common processing errors of acrylic is failure to take this considerable thermal expansion into account. PMMA sheets must necessarily be mounted with sufficient tolerance.

Polymethyl methacrylate is flammable. However, the flame extinguishes as soon as the ignition source is removed.

Like any polymer, PMMA is also obtained by polymerizing individual monomers. Thus, polymethyl methacrylate can be synthesized by radical or anionic polymerization of methyl methacrylate.

In contrast to other plastics, the chemical, physical and mechanical properties of PMMA cannot be influenced by the selection of reaction partners, but by specifically influencing the reaction conditions. Thus, a change in the reaction temperature always results in a variation of the chain length. This influences the physical properties of the finished product.

Today, large-scale production of PMMA is carried out by two different processes:

• Extrusion - In this process, the plastic is forced through a die during polymerization and then shaped into the desired form.
• Casting - In this process for producing PMMA, the plastic is cast directly into the desired shape, for example as an acrylic sheet.

Extruded and cast polymethyl methacrylate differ from each other, sometimes very significantly, in individual properties. Extruded PMMA, for example, is generally softer and more prone to cracking. Cast polymethyl methacrylate is therefore more suitable for demanding applications, as it is considered to be of higher quality.

In addition to the casting process for the production of high-quality PMMA products, the following processes are particularly suitable for the production of various acrylic glass products:

• Injection molding - In this process, polymerized PMMA is liquefied and pressed under pressure into the desired shape, where it finally cools. This process can be used to form workpieces up to a mass of about 150 kilograms.
• Centrifugal casting - This process is particularly suitable for synthesizing rotationally symmetrical workpieces, such as pipes and hoses. The molded material is pressed into a mold rotating about its central axis and pressed against the wall of the mold by the resulting centrifugal force. Workpieces produced by centrifugal casting are characterized by high strength and very few pores.
• Extrusion - This process is similar to injection molding. However, the polymethyl methacrylate is synthesized during the injection process.

Polymethyl methacrylate is a versatile plastic that has a wide range of uses in the following areas:

• In furniture construction, transparency, hardness and good formability ensure a wide range of applications.
• In aquaristics, acrylic glass is far superior to conventional mineral glass due to its good formability and break resistance. With the help of PMMA, lightweight tanks with curved panorama panes can be built.
• In industry, large-area glazing, seals and spotlights are just some of the many applications for polymethyl methacrylate.
• The cosmetics industry uses polymethyl methacrylate in a variety of exfoliating products because of its non-toxicity to humans.
• High-quality dentures are made from dyed polymethyl methacrylate.
• Due to its thermal properties, polymethyl methacrylate is a versatile printing material.
  
  

PMMA can be found in many furnishings

Interior architects and designers have long relied on PMMA as a material for building elegant and modern furniture. The combination of low specific weight, high durability and great book resistance makes polymethyl methacrylate a well-suited material for the following furniture:

• For display cases, modern and curved glass fronts can be realized, which convince with excellent optical properties.
• Innovative seating furniture can be produced by means of various casting processes.
• Modern glass tables usually have high-quality and scratch-resistant table tops made of acrylic glass.

However, PMP (polymethylpentene), which is physically and mechanically quite similar, is less suitable for these purposes and is used primarily for the production of microwaveable tableware.

For display cases, modern and curved glass fronts can be realized, which convince with excellent optical properties

PMMA is an ideal material for shelves and showcases for the stylish presentation of porcelain, books and art objects due to its high optical permeability and stability. In combination with wood and steel, furniture makers design beautifully shaped pieces of furniture.

Innovative seating furniture can be produced by means of various molding processes

Polymethyl methacrylate can be reversibly formed and, due to its high stability, virtually invites people to question traditional shapes and completely reinterpret familiar furnishings such as chairs. Due to its good colorability, PMMA has been a preferred material for furniture designers for some time.

Modern glass tables usually have high quality and scratch resistant acrylic table tops

Special surface coatings ensure that acrylic glass tops are very scratch-resistant. Due to its low density, PMMA is therefore ideally suited for the production of highly transparent table tops for office furniture or dining room furnishings.

The advantages of polymethylmethacrylate in aquarium construction

Polymethylmethacrylate has become indispensable in both professional and amateur aquariums. If the curved shapes for panoramic basins play a major role in public show aquariums, PMMA is convincing in the amateur sector due to its easy workability. Acrylic glass sheets are comparatively light and can be sawed, drilled, milled and glued. This means that even amateur aquarists can quickly and easily fulfill the dream of their own, individually designed tank..

Since even relatively small tanks are subject to a pressure on the panes that should not be underestimated, it makes sense to use high-quality branded plastics when building aquariums, which are usually technically superior to financially cheaper products.

The high scratch resistance makes PMMA a popular plastic for a variety of optical elements

Polymethyl methacrylate has high transparency, great rigidity and dimensional stability as well as great hardness and the highest scratch resistance of all plastics. It also features excellent resistance to weathering. This makes PMMA an ideally suited material for optical instruments, which were previously usually made of crystal glass. These include:

• Eyeglass and watch lenses,
• magnifying glasses, lenses, prisms and diffusing screens,
• optical fibers and fiber optic cables,
• plates with LED coloring, and
• optical storage devices.
  
  

In which industrial sectors is polymethyl methacrylate used?

For industrial manufacturing, polymethyl methacrylate is a raw material that plays a major role in almost all production areas. These include:

• Automotive - Coated PMMA is used here for turn signals, tail lights and trim.
• Construction - Industrial flooring, glazing and coated roofs can be made from PMMA.
• Optics - Coated PMMA is used to make lightweight, high-quality lenses and optical fibers.
• Mechanical engineering - Shatterproof protective hoods and shields are made from PMMA.
  
  

Polymethyl methacrylate increases the durability of make up

Although PMMA is now replaced by other substances in many exfoliating products, it still plays a major role in creams and lotions as a stabilizer and active ingredient carrier. Thus, PMMA in various micro-grains with high oil absorption capacity serves to improve shelf life or to adapt the product to different skin types. PMMA thus belongs to the class of texture additives and is found, among other things, in:

• care products,
• make-ups and
• sun creams
  
  

In n dentistry, polymethyl methacrylate can meet high optical demands

After taking an impression of the jaw, dental technicians use dyed polymethylmethacrylate to produce lightweight, high-quality dentures. Due to its good dyeability, PMMA can be used to manufacture such aids in any desired color.

Important role in 3D printing

Good thermal properties and high dimensional stability make PMMA filaments a popular raw material for 3D printing technology. This process is used for the cost-effective and rapid creation of prototypes or small series. Unlike other printing filaments, however, PMMA has a tendency to warp, i.e. to bulge and, in the worst case, even detach from the printing plate. However, special printing plates and additives provide a remedy here, so that printed workpieces also benefit from the outstanding properties of polmethyl methacrylate.