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polymethylmethacrylate (PMMA)<br>methyl methacrylate resin
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( C <sub>5</sub> O <sub>2</sub> H <sub>8</sub>)<sub>''n''</sub>
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varies
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119 g/cm³
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130-140 °C (265-285 °F)
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2000 °C (392 °F)
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('''PMMA''') or poly (methyl 2-methylpropanoate) is the Synthetic Polymer of Methyl Methacrylate . This Thermoplastic and Transparent Plastic is sold by the tradenames '''Plexiglas''', '''Limacryl''', '''R-Cast''', '''Perspex''', '''Plazcryl''', '''Acrylex''', '''Acrylite''', '''Acrylplast''', '''Altuglas''', '''Polycast''' and '''Lucite''' and is commonly called '''acrylic glass''' or simply '''acrylic'''.
The material was developed in 1928 in various laboratories and was brought to market in 1933 by Rohm And Haas Company .
, the Monomer that makes up PMMA]]
The material is often used as an alternative to Glass . Differences in the properties of the two materials include
- PMMA 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.
- PMMA has a higher Impact Strength than glass and does not shatter but instead breaks into large dull pieces.
- PMMA is softer and more easily scratched than glass. This can be overcome with scratch-resistant coatings.
- PMMA is typically processed at a lower temperature than glass, just 240-250 °C.
- PMMA Transmits more light (up to 93% of visible light) than conventional glass. MatWeb material property database - Overview of General Purpose Acrylic molding resin However, there exist special optical grades of glass that can transmit up to 98% of light. http://www.matweb.com/search/SpecificMaterial.asp?bassnum=CGLACO23 MatWeb material property database - High optical transmitance glass
- Unlike glass, PMMA does not filter .
- PMMA allows Infrared light of up to 2800 Nm Wavelength to pass. IR of longer wavelengths, up to 25,000 nm, are essentially blocked. Special formulations of colored PMMA exist to allow specific IR wavelengths to pass while blocking Visible Light (for Remote Control or heat sensor applications, for example).
PMMA can be joined using Cyanoacrylate cement (so-called "Superglue"), or by using liquid Di- or Trichloromethane to dissolve the plastic at the joint which then fuses and sets, forming an almost invisible Weld . PMMA can also be easily polished to restore cut edges to full transparency.
To produce 1 Kg of PMMA, about 2 kg of Petroleum is needed. In the presence of oxygen, PMMA ignites at 460° C and burns completely to form only Carbon Dioxide and Water .
The polymer of methyl acrylate, PMA or poly(methyl acrylate), is similar to poly(methyl methacrylate), except for the lack of methyl groups on the backbone carbon chain. Polymethyl acrylate and polyethyl acrylate, Encyclopædia Britannica PMA is a soft white rubbery material that is softer than PMMA because its long polymer chains are thinner and smoother and can more easily slide past each other.
PMMA or Acrylic is a versatile material and has been used in a wide range of fields and applications.
- PMMA Acrylic glass is commonly used for constructing residential and commercial Aquarium s.
- PMMA is used in the lenses of exterior lights of automobiles. Kutz, Myer, Handbook of Materials Selection. John Wiley & Sons 2002. pg 341
- The spectator protection in Ice Hockey stadiums is made of PMMA.
- Motorcycle Helmet visors
- Police vehicles for Riot Control often have the regular glass replaced with acrylic to protect the occupants from thrown objects.
- Lucite was used for windows on the Bathyscaphe Trieste which descended to the lowest point on the ocean floor, the Challenger Deep .
- Polycast acrylic sheet is the most widely used material in aircraft transparencies (windows). In applications where the aircraft is pressurized, stretched acrylic is used.
- PMMA has a good degree of compatibility with Human Tissue , and can be used for replacement Intraocular Lens es in the Eye when the original lens has been removed in the treatment of Cataract s. Hard Contact Lens es are frequently made of this material. Soft contact lenses are often made of a related polymer, where acrylate monomers containing one or more Hydroxyl Group s make them Hydrophilic .
- In and not so much like a glue in Arthroplasty . Although sticky, it primarily fills the spaces between the prosthesis and the bone preventing motion. It has a Young's Modulus between Cancellous Bone and Cortical Bone . Thus it is a load sharing entity in the body not causing Bone Resorption . Miller, Review of Orthopaedics, 4th Edition, p 129.
- Denture s are often made of PMMA, and can be colour-matched to the patient's teeth. In Cosmetic Surgery , tiny PMMA microspheres suspended in some biological fluid are injected under the skin to reduce wrinkles or scars permanently.
- Acrylic Paint essentially consists of PMMA suspended in Water ; however since PMMA is Hydrophobic , a substance with both hydrophobic and Hydrophilic groups needs to be added to facilitate the Suspension .
- Modern Furniture makers, especially in the 1960s and 1970s, seeking to give their products a Space Age esthetic incorporated Lucite and other PMMA products into their designs, especially office chairs. Many other products (for example, guitars) are sometimes made with acrylic glass, giving otherwise ordinary objects a transparent or futuristic look.
- Perspex has been used as a surface to paint on, for example by Salvador Dalí .
- Occasionally used as a Glass substitute in Picture Framing , due to its relatively inexpensive cost, light weight, and shatter-resistant nature, as well as the fact that it can be ordered in larger sizes than standard picture-framing glass. Conventional glass may or may not be preferred.
- From approximately the 1960s onward, sculptors and glass artists began using acrylics, especially taking advantage of the material's flexibility, light weight, cost and its capacity to refract and filter light.
- The material is used to produce Laserdisc s, and sometimes also for DVD s, but the more expensive Polycarbonate (also used for CD s) has better properties when exposed to moisture.
- Used for the "bubble" on the front of submarines such as Alicia (submarine) .
- Artificial fingernails are made of acrylic.
- In the 1960s, luthier have also made acrylic guitars.
- Recently a Blacklight -reactive Tattoo Ink using PMMA Microcapsule s was developed. This ink is reportedly safe for use, and claims to be Food And Drug Administration approved for use on wildlife that may enter the food supply.
- In Semiconductor research and industry, PMMA aids as a Resist in the Electron Beam Lithography process. A solution consisting of the polymer in a Solvent is used to Spin Coat Silicon wafers with a thin film. Patterns on this can be made by an electron beam (using an Electron Microscope ), deep UV light (shorter wavelength than the standard Photolithography process), or X-ray s. Exposure to these creates chain scission or (de- Cross-linking ) within the PMMA, allowing for the selective removal of exposed areas by a chemical developer, making it a positive photoresist. PMMA's advantage is that it allows for extremely high resolution (nanoscale) patterns to be made. It is an invaluable tool in Nanotechnology .
- Small strips of PMMA are used as Dosimeter devices during the Gamma Irradiation process. The optical density of PMMA changes as the Gamma dose increases and can be measured with a Spectrophotometer .
- It is used as a light guide for the backlights in TFT-LCDs .
- Ludwig-Musser makes a line of acrylic drums called Vistalites. They are well known as being used by Led Zeppelin drummer John Bonham .
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