Engineering Plastics

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Engineering plastics

Engineering plastics are a group of plastic materials that have better mechanical and/or thermal properties than the more widely used commodity plastics (such as polystyrene, PVC, polypropylene and polyethylene).  Being more expensive, engineering plastics are produced in lower quantities and tend to be used for smaller objects or low-volume applications (such as mechanical parts), rather than for bulk and high-volume ends (like containers and packaging).  

The term usually refers to thermoplastic materials rather than thermosetting ones. Examples of engineering plastics include acrylonitrile butadiene styrene (ABS), used for car bumpers, dashboard trim and Lego bricks; polycarbonates, used in motorcycle helmets; and polyamides (nylons), used for skis and ski boots.  Engineering plastics have gradually replaced traditional engineering materials such as wood or metal in many applications. Besides equalling or surpassing them in weight/strength and other properties, engineering plastics are much easier to manufacture, especially in complicated shapes.

Acrylonitrile butadiene styrene

Acrylonitrile Butadiene Styrene (ABS) is an opaque thermoplastic and amorphous polymer. “Thermoplastic” (as opposed to “thermoset”) has to do with the way the material responds to heat. Thermoplastics become liquid (i.e. have a “glass transition”) at a certain temperature (221 degrees Fahrenheit in the case of ABS plastic). They can be heated to their melting point, cooled, and re-heated again without significant degradation. Instead of burning, thermoplastics like ABS liquefy which allows them to be easily injection molded and then subsequently recycled. By contrast, thermoset plastics can only be heated once (typically during the injection molding process). The first heating causes thermoset materials to set (similar to a 2-part epoxy), resulting in a chemical change that cannot be reversed. If you tried to heat a thermoset plastic to a high temperature a second time it would simply burn. This characteristic makes thermoset materials poor candidates for recycling. ABS is also an amorphous material meaning that it does not exhibit the ordered characteristics of crystalline solids.

ABS is most commonly polymerized through the process of emulsion (the mixture of multiple products that don’t typically combine into a single product). A well known example of an emulsified product is milk. ABS is also created, albeit less commonly, by a patented process known as continuous mass polymerization. Globally, the most common methodology to create ABS is the emulsion process.

ABS has a strong resistance to corrosive chemicals and/or physical impacts. It is very easy to machine and has a low melting temperature making it particularly simple to use in injection molding manufacturing processes or 3D printing on an FDM machine. ABS is also relatively inexpensive (prices, currently around $1.50 per pound, typically fall somewhere between those of Polypropylene  (“PP”) and Polycarbonate (“PC”). ABS plastic is not typically used in high heat situations due to its low melting point.  All of these characteristics lead to ABS being used in a large number of applications across a wide range of industries.

Polycarbonates

Polycarbonate is a dimensionally stable, transparent thermoplastic with a structure that allows for outstanding impact resistance. With high-performance properties, Polycarbonate is the leading plastic material for various applications that demand high functioning temperatures and safety features. Because of its durable make-up, polycarbonate is often the preferred thermoplastic over materials like PMMA and Acrylic. Polycarbonates are unique in its working temperatures and ability to experience minimal degradation between heating and cooling points. Polycarbonate features a high working temperature of 266 degrees Fahrenheit and cooling temperatures at -40 degrees Fahrenheit.

Features of polycarbonate

PC is a good material of choice in industry due to its versatile characteristics, eco-friendly processing and recyclability. They have the unique set of chemical and physical properties making them suitable over glass, PMMA, PE, etc.  

 

Toughness and High Impact Strength

Polycarbonate has high strength that makes it resistant to impact and fracture and hence provides safety and comfort in application demanding high reliability & performance. They are virtually unbreakable.  

Transmittance

PC is an extremely clear plastic and can transmit over 90% of light as good as glass. PC sheets are available in a wide range of shades which can be customized depending on the end-user application.

Lightweight

The benefits allows provides OEMs virtually unlimited possibilities for design compared with glass. The property allows increased efficiency, makes installation process easier and reduces overall transportation costs.  

Protection from UV Radiations

Polycarbonates can be designed to block ultraviolet radiation and provide 100% protection from the sun’s harmful UV rays.   Optical Nature – Thanks to its amorphous structure, PC offers excellent optical properties. Refractive index of clear polycarbonate is 1.584.  

Chemical Resistance

Polycarbonate exhibits good chemical resistance against diluted acids, aliphatic hydrocarbons and alcohols; moderate chemical resistance against oils and greases. PC is readily attacked by diluted alkalis, aromatic and halogenated hydrocarbons. Manufacturers recommend to clean PC sheets with certain cleaning agents which do not affect its chemical nature. It is sensitive to abrasive alkaline cleaners.  

 

 

Heat Resistance

Polycarbonates offers good heat resistance and are thermally stable upto 135°C. Further heat resistance can be improved by adding flame retardants without impacting material properties.

Applications of polycarbonates

Popular uses of polycarbonate can include aircraft parts, data storage devices, dome lights, eye protection, multiwall sheets, electronic components and more. Due to polycarbonates ability to withstand extreme temperatures for prolonged periods of time, it is often used in components for various industries, including:

  • Aircrafts and Aerospace Components
  • Greenhouses and Agriculture
  • Industrial Lighting
  • Electronic Components
  • Automotive Components
  • Machinery Guards

 


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