Polymethyl methacrylate PMMA

PMMA

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Polymethyl methacrylate, which is abbreviated as PMMA, is a clear plastic, used as a shatterproof replacement for glass. On both sides of the Atlantic PMMA is also marketed as Plexiglas.

PMMA is more than just plastic and paint. Often lubricating oils and hydraulic fluids tend to get really viscous and even gummy when they get really cold. This is a real pain when you're trying to operate heavy equipment in really cold weather. But when a little bit PMMA is dissolved in these oils and fluids, they don't get viscous in the cold, and machines can be operated down to -100 ^oC (-150 ^oF), that is, presuming the rest of the machine can take that kind of cold!

PMMA is a vinyl polymer, made by free radical vinyl polymerization from the monomer methyl methacrylate.

• Plastic Optical Fiber
  abbreviated POF, typically uses PMMA as the core material, and fluorinated polymers for the clad material. In large-diameter fibers, 96% of the cross section is the core that allows the transmission of light.
  It is being focused on for the following fields in particular: 
  • Digital home appliance interfaces
  • Home networks
  • Car networks 
  • Illuminations 
  
  
• Non textile applications
  - sheets
  - glass replacement

• flat yarn
• monofilament
• fibers

• POF is strong and very difficult to bend. There is only a small loss even when bent to a 25mm radius. Therefore, it can be installed within walls or other narrow areas. It is also suitable for lighting in tight locations.
   
• Installation work is extremely simple. There are several methods, but the one common for transmission is the Hot Plate method. In this method, it takes advantage of the fact that the material used is plastic, so that fiber ends are heated and softened, then pushed against a mirrored surface. The process is quick and can be repeated with very little deviation. Therefore, installation is simple even for those who have never handled optical fiber.
   
• Normally, a 650nm (red) LED is used as the light source for POF optical transceiver modules. Since this is within the visible light spectrum, it acts as an eye safety feature because the user can easily tell when he/she is in danger of directly viewing the light beam. Also, since 650nm will be the wavelength used for a large number of DVD light sources, we can expect the cost to drop even further.
• POF is not suitable for long-distance transmission. compared with quartz fiber, there is a large transmission loss. However home and office applications do not require transmission over great distances, having a need for ease-of-use, low cost, and stability instead. POF is best suited for use in these environments.
   
• Since POF is strong against vibration and bending, in addition to its conventional uses in high-speed trains and automobiles it has also recently been applied to car networks inside the vehicle due to an increasing multimedia demand from drivers.
   
• Since POF transmits very little infrared light, it can be used for cold lighting (lighting that do not produce heat), for semiconductor manufacturing equipment and the lighting displays of artwork.

Principles of Optical Fiber

Optical fiber transmits light. But, what prevents the light from escaping from the fiber? The answer is based on a principle that we experience every day.

While swimming at the beach as a child, have you ever thought that you were safely in shallow water only to be surprised to find that it was too deep to touch the bottom? When you look straight down into a clear lake or puddle, you can see its bottom. However, when you view it at an angle and look off into the distance, the distant scenery is reflected upside down. This is caused by the difference in the index of refraction between the water and air, which you probably learned about in grade school.

Although optical fiber appears to be only a simple thread, it is actually composed 2 structures similar to water and air. The area where light is transmitted is called the core, and the external area is called the clad.   When light enters the area between 2 materials with different indexes of refraction (boundary face), the light will be either entirely reflected or a portion of it will be refracted, depending on the angle. If the light can be kept at an angle where it is entirely reflected, it will become trapped inside and transmitted along the fiber.