Plastics Flashcards
Where does PLASTIC come from?
Crude oil
What are POLYMERS?
They are created by bonding molecules together.
What is a MONOMER?
A monomer is a relatively small molecule that can chemically bond to other monomers forming a polymer.
!!REMEMBER ALL PLASTICS ARE POLYMERS!!
What are THERMO SETTING PLASTICS?
Once ‘set’ these plastics cannot be reheated to soften, shape and mould.
The molecules of these plastics are cross linked in three dimensions and this is why they cannot be reshaped or recycled. The bond between the molecules is very strong.
What are THERMOPLASTICS?
These plastics can be re-heated and therefore shaped in various ways.
They become mouldable after reheating as they do not undergo significant chemical change.
Reheating and shaping can be repeated.
The bond between the molecules is weak and become weaker when reheated, allowing reshaping.
Thermoplastics tend to be composed of ‘long chain monomers’.
These types of plastics can be recycled.
Give examples of THERMOSETTING PLASTICS
Adhesives (Araldite) Polyurethane Melamine formaldehyde Urea formaldehyde Polyester resin
Give examples of THERMOPLASTICS
Acrylic Polythene Polyvinyl chloride Polyethylene Polycarbonate
Some extra useful plastics
Styrofoam
Expanded polystyrene
Nylon
What is POLYURETHANE used for?
It’s a thermosetting plastic
This forms the basis of many paints and varnishes because it is very tough and has water resistant qualities
What is MELAMINE FORMALDEHYDE used for?
It’s a thermosetting plastic.
Used in the production of plastic laminates because of its smooth surface and hygienic qualities.
It is also used in electrical plugs and sockets because it can be cast and it is an excellent insulator.
What is UREA FORMALDEHYDE used for?
It’s a thermosetting plastic.
Urea Formaldehyde has physical properties of high hardness and high toughness, making it suitable for strong, knock-resistant electrical fittings. It is also scratch resistant and a very good electrical insulator, making electrical fittings manufactured from this polymer safe to use.
What is POLYESTER RESIN used for?
It’s a thermosetting plastic.
If resins are combined with a material such as fibre glass the result is a very tough material that can resist impact.
This type of material is known as a glass reinforced plastic (GRP) and is used in car body repairs, sailing boats, corrugated sheet because of its lightness, toughness and resistance to water.
What is ACRYLIC used for?
It’s a thermoplastic
This is the most common plastic in a school workshop.
It is purchased usually in the form of sheets and comes in a range of colours. It can be translucent (e.g. smoked), transparent or opaque.
It is resistant to most acids and weather conditions.
What is POLYTHENE used for?
It’s a thermoplastic
Can be moulded into almost any form due to its excellent moulding qualities.
Used for the production of bottles, bowls, toys, tube etc… It is available in large sheets.
There are two types: High density which is rigid and hard, and low density which is tough and flexible.
Machine parts are generally made from high density polystyrene whilst bottles are made from the low density polystyrene.
What is POLYVINYL CHLORIDE used for?
It’s a thermoplastic
Better known as PVC.
It is a tough material which can be purchased as a hard material or alternatively a flexible form.
It can be welded or bonded with an adhesive. It has a range of uses including water pipes, raincoats, long play records, coating on electrical wires and many more
