Mr BILLINGTON
Thermosetting Plastic
Material Properties - Thermoforming Plastics Continued
PET, or polyethylene terephthalate, is a polymer manufactured from ethylene terephthalate monomors as the most commonly used plastics in the polyester family. It is globally recognized as a safe, non-toxic, strong, lightweight, flexible material that is used widely in the food/drink industry. Around 70% of drinks bottles are manufactured from PET due to its extremely low water absorption, high chemical resistance, shatterproof, naturally colourless and recyclable (Group 1). It is one of the most recycled plastics in the world accounting for over 7 millions tonnes a year with around 40% of energy recovered
PET is also used as a fibre in the textiles industry accounting for 60% of global PET production. Commonly referred to as Polyester it is used widely for home furnishings, shirts, trousers, jackets, hats, bed sheets, blankets & upholstered furniture. It is highly stain resistant with only one class of dye, disperse dye, that will colour it and is often blended with natural fibers to reduce shrinking and wear
As with PVC, there is health concerns over the use of Phthalates as drinks bottles but these are irrelevant given that they are not used to manufacture PET. In fact there is no proven health risk associated with PET. The primary disadvantage of PET use is being non-biodegradable, like most plastics, contributing to huge levels of litter and unnecessary landfill waste. Equally, it is prone to oxidisation and may degrade slighty, affecting the taste of the liquid contained due to Acetaldehyde
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ABS, or Acrylonitrile Butadiene Styrene, is a co-polymer plastic made through a polymerisation of styrene & acrylonitrile in a solution of polybutadiene. It is used primarily for it's high impact resistance, heat resistance, lightweight and toughness. It is widely used for children's toys and product casings as it is naturally white in colour and therefore ideal for mixing with dyes giving an even, long-lasting, fade resistant colour finish. Equally, it's excellent impact strength and low cost ensure products are durable and the internal components are well protected
Unlike most plastics, ABS is easily machined through a range of common processes. It's strength comes from the combination of strength and rigidity from acrylonitrile & styrene polymers, with the toughness of polybutadiene rubber. This does, however, come at a cost of around double that of Polystyrene. It is also used widely in 3D extrusion printing as a durable alternative to PLA
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Acrylic, or Perspex, is commonly used for a wide range of applications for it's transparency, impact resistance, and elasticity. It is formed from acrylate monomors using acrylic acid as a base into Poly(methyl methacrylate), or PMMA. It's transparent properties make it an ideal replacement for glass as it is shatter resistant, due to a high impact strength, and lightweight, with a density over half of glass. It has widely replaced glass in aquariums for this reason as well as its use as screens and lenses
Acrylic, or Perspex, is commonly used for a wide range of applications for it's transparency, impact resistance, and elasticity. It is formed from acrylate monomors using acrylic acid as a base into Poly(methyl methacrylate), or PMMA. It's transparent properties make it an ideal replacement for glass as it is shatter resistant, due to a high impact strength, and lightweight, with a density over half of glass. It has widely replaced glass in aquariums for this reason as well as its use as screens and lenses
Acrylic is available in a array of opaque and translucent colours through the addition of dye pellets, and coatings can be added to enhance certain properties such as infrared light filtering. It is also chemically non-reactive and used widely in the food & medical industry as it releases no toxic chemicals. This property makes acrylic equally suited to outdoor applications such as greenhouses, coupled with it's U.V resistance over other plastics. Acrylic is also very versatile due to its excellent formability when heated
However, Acrylic can be brittle when using a thickness of up to 6mm, making it prone to fracture, and has a lower surface hardness than glass, scratching easily. PMMA also has a higher material cost than glass, is less energy efficient & toxic to manufacture due to chemical fumes produced from polymerisation. It is also non-biodegradable, as with most plastics, and difficult to recycle falling into Group 7, which are rarely taken for recycling.
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Polyhydroxybutyrate (PHB), or Biopol, is a unique polymer that unlike others does not rely on petrochemicals. Instead it is produced by microorganisms that compost biomass from plant sugars as glucose, typically from corn starch, which makes it a completely renewable plastic. By restricting the amount of nutrients (nitrogen) available to the bacteria it begins to absorb carbon from the air and bind it with the glucose it consumes to make a co-polymer. This is then processed into PHB much like other thermoforming plastics. It is classified under the polyester family of polymers and has properties similar to PP
Uniquely, PHB is completely biodegradable and will breakdown in landfill safely over time. This property makes it ideal for high volumesingle use products (cups, razors, cutlery, plasters) but also suited to surgical applications that negate the removal of the implant (stiches, pins). Equally, it is insoluble in water which allows it to sink and prevent waste pollution in rivers/lake/seas. Although seemingly ideal, the manufacture incurs a much higher cost and results in a poor impact/chemical resistance limiting its use for packaging. Recently, PLA (Polylactic Acid) has become a sustainable choice for 3D printing
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