Design and Technology students have to be familiar with a range of thermoplastic and thermoset plastics, elastomers, their properties and common uses. This article provides an overview of this material to help students revise for the examination.
A brief introduction to plastics
‘Plastics’ are a type of synthetic polymer (a polymer is a long chain of linked molecules in repeating patterns). Human bodies and those of plants and animals are built from natural polymers. For example, cellulose, protein, and DNA are all made from natural polymers. Rubber is a natural polymer and traditionally comes from latex in the sap of rubber trees (although there are now synthetic forms of rubber).
Scientists can create plastics with almost any properties they want – making them lightweight yet strong, waterproof, mouldable into any shape, and incredibly versatile for product design.
Thermoplastics
- Soften when heated
- Most common type of plastic
- Typically recyclable (although not always – i.e. acrylic is not)
- Relatively cheap
- Many colours – including transparent / translucent / opaque
- Weather resistant
- Easily moulded and remoulded (but become weaker each time)
- Can be formed in a variety of ways (vacuum forming, blow moulding, injection moulding)
THERMOPLASTICS
Acetate
Properties
Uses
Excellent transparency – allows people to see product clearly
Glossy – gives a high quality appearance
Reasonable rigidity – provides structure and protection
Food safe – generally considered safe to contact food
Overhead projector sheets
Food packages – especially those that benefit from visibility
Cake box ‘windows’
Cosmetic packaging
Toy and electronic packaging
Fully transparent gift boxes
Acrylic
Properties
Uses
Also known as PMMA (polymethyl methacrylate)
Excellent transparency
Very rigid, hard (although can be scratched)
Glossy – premium high-quality appearance
Excellent weather & UV resistance
Quite brittle – but more shatter resistant than glass
Higher cost compared to other packaging materials
Point-of-sale displays
Storage containers
Packaging designed to be reused multiple times
Counter top display units
PVC / vinyl
Properties
Uses
Polyvinyl Chloride (PVC) is a type of vinyl
Can be hard & rigid OR flexible, depending on additives
Good chemical resistance to many chemicals
Resilient and tough
Lightweight
Not food safe – can leach chemicals into food
Vacuum forming
Blister packs
Tray inserts
PVC pipes
Linoleum flooring (vinyl)
Raincoats / aprons / shower curtains / gloves / boots
Self-adhesive vinyl for printing or cutting using a vinyl cutter (a type of plotter cutter)
Expanded polystyrene
Properties
Uses
Very lightweight
Soft and cushioning
Good sound and heat insulation
Styrofoam™ is a brand name for extruded polystyrene, which is more dense with smaller, more uniform cells
Not recyclable or reworkable like other thermoplastics
Crumbly – not very resilient
Packaging layers inside boxes to protect items during shipping
Insulation in buildings
Bean bag stuffing
Styrofoam™ cups
Model-making
Polystyrene
Properties
Uses
Naturally clear and transparent (can be coloured)
Rigid
Easy to form
Food safe
Good chemical resistance
Brittle
Poor impact resistance
Disposable cups & plates
Plastic knives & forks
Laboratory equipment (petri dishes etc)
Cosmetic containers
HIPS
Properties
Uses
High Impact Polystyrene
Tough, durable and shatter resistant (modified with rubber particles overcoming brittleness)
Rigid
Good chemical resistance
Lightweight
Opaque (not transparent)
UV sensitive (degrades and becomes brittle in sunlight)
Heat sensitive (can warp or deform at low temperatures)
Appliances (computers, inside fridges, TV cases)
Toys and recreational products
Signs and point-of-sale displays
Nylon
Properties
Uses
Very strong and tough
High tensile strength
Flexible
Excellent abrasion resistance
Good chemical resistance
Absorbs moisture
UV sensitive
More expensive
Rope and fishing line
Clothing / textiles
Carpets / rugs
Brush bristles
LDPE
Properties
Uses
Low density polyethylene
Flexible
Good transparency
Good chemical resistance
Good insulation properties
Polyethylene is most common plastic (LDPE + HDPE)
Low tensile strength
Low stiffness
Can be formulated into PE-coated card (also known as poly-coated card), providing a waterproof protective barrier lining / sealing cardboard such as for milk and juice cartons
Plastic bags
Food wrap / cling film
Shrink-wrapped products (the base tray is often polystyrene)
Small squeeze bottles
Electrical cable insulation
HDPE
Properties
Uses
Tough, durable, impact resistant
Hard and rigid / high stiffness
Good chemical resistance
Low permeability – excellent protection against moisture, odors, and flavors
Less flexible than LDPE
Can become brittle and crack under stress
Not transparent
Milk jugs and drink bottles
Shampoo bottles
Fuel tanks
Playground equipment
Recycling bins
PET
Properties
Uses
polyethylene terephthalate (note: this is completely different to LDPE and LDPE despite similar name)
Excellent clarity and transparency
Shatter resistant
Good barrier against moisture and gas
Melts at low heats (not good for hot food)
Water and soft drink bottles
Food packaging and containers
Blister packs
Polyester clothing
Carpet
Polypropylene (PP)
Properties
Uses
Withstands repeated bending/flexing without breaking)
Excellent chemical resistance
High melt point
Stiff
Easy to mould fine detail
Very common plastic
Brittle at very low temperatures
Food containers (yoghurt cups, margarine tubs)
Bottle caps
Flip-top bottles (acts as a hinge)
Storage containers
Outdoor furniture
Wheelable suitcases
Toys and sporting goods
Thermal undergarments
Polycarbonate (PC)
Properties
Uses
Extremely tough (virtually unbreakable)
Excellent optical clarity and transparency
Can leach BPA (bisphenol A, which mimics estrogen – a hormone in the human body), leading to replacement in food-contact applications)
Difficult to recycle
More expensive
Safety glasses
Phone / laptop housings
Car headlight lenses
Riot shields
Laminated layers in bullet proof glass
CDs / DVDs
ABS
Properties
Uses
Acrylonitrile butadiene styrene
Good impact resistance and toughness
Easy to machine, drill, and paint
“Versatile workhorse” plastic, tough enough for structural parts
Not food safe
Lego and toys
Computer keyboards and housings
Instruments like recorders and clarinets
3D printing filament
Thermosetting plastics
- Cannot be remelted
- Hard, rigid, and heat-resistant
- Often brittle compared to thermoplastics
- Harder to recycle (however can sometimes be ground into flakes or fibres for composite products etc)
THERMOSETTING PLASTICS
Polyester resin
Properties
Uses
Used as part of glass reinforced plastic (GRP) (also known as fibreglass)
Durable, with good chemical and weather resistance
Vapour is toxic and flammable
Begins curing immediately once catalyst added – limited working time
Glass fibres can cause irritation
Sticky, messy, and hard to clean up
Boat hulls
Cladding panels
Swimming pools
Water tanks
Melamine
Properties
Uses
Full name: melamine formaldehyde (MF)
Hard, scratch-resistant surface
Stain resistant
Can be molded with decorative patterns/colors
Not microwave safe – can release formaldehyde at high temperatures
Kids plates, cups, tableware
Laminated benchtop surfaces
Furniture veneers
Melamine coated chipboard
Serving trays
Urea formaldehyde
Properties
Uses
A resin with excellent adhesive strength
Hard and durable
Heat resistant
Releases formaldehyde gas (many applications are being phased out for this reason)
Brittle and can crack
Prone to discolouration with time
Poor outdoor durability
Adhesive in plywood, MDF, chipboard and other manufactured wood products
Laminates
Wrinkle resistant fabrics
Coatings for electrical products like lamps
Injected as a shaving cream-like foam into cavities in walls etc, after which it is heated to harden, providing insulation (banned in some countries)
Phenol formaldehyde
Properties
Uses
Also known as phenolic resin
Strong and durable
Waterproof
Heat resistant
More expensive than urea formaldehyde
Dark brown/black (can’t be made clear)
Requires heat and pressure to cure
Releases formaldehyde (but less than urea formaldehyde)
Marine/exterior grade plywood
Laboratory countertops
Billiard balls (i.e. used in pool)
Laminated film on top of manufactured boards
Anti-slip surfaces
Epoxy resin
Properties
Uses
Sticks well to most materials
Very strong and durable
Waterproof
Cures at room temperature after two components are mixed together (no special equipment needed)
Clear / transparent options
Expensive compared to other glue
Toxic fumes while mixing
Yellows / degrades in UV light
Difficult to remove / repair
High strength structural repairs (joints in boat building etc)
Floor coatings
Arts & crafts
Elastomers
- A type of polymer with elastic properties at room temperature (can stretched or deform and then return to its original shape when the force is removed)
- The word comes from “elastic polymer”
- Often more flexible when heated and stiffer when cold
- Widely used in applications requiring flexibility, vibration damping, or sealing
Thermoplastic Elastomers (TPEs) behave like rubber at room temperature but can be melted and reshaped when heated, making them recyclable and easily formed.
ELASTOMERS
Rubber
Properties
Uses
Can be natural (from rubber trees) or synthetic, like styrene-butadiene rubber (SBR)
Flexible
Resistant to water (provides good sealing)
Absorbs vibration / shock
Provides friction / grip, without damaging surfaces
Degrades in sunlight – cracks and becomes brittle
Tyres
Jar seals
Hoses (not normal garden hosese these are often PVC)
Conveyor belts
Rubber bands
Window seals
Latex is the milky white sap from rubber trees (can be synthetic), while rubber is the finished, solid product made from processing latex
Silicone
Properties
Uses
Flexible, soft, and pliable
Waterproof
Food safe and non-toxic
Extreme temperature resistance – can go in hot oven without melting
UV/weather resistant – doesn’t degrade in sunlight like rubber or become brittle with age
More expensive than rubber
Can’t match rubber’s strength for tyres etc
Phone cases
Flexible baking pans (muffin trays etc)
Spatulas
Food container seals
Baby dummies and baby bottle teats
Medical tubing
Neoprene
Properties
Uses
Stretchy synthetic black rubber
Strong, durable – tear resistant
Excellent thermal insulation
Waterproof – can be made breathable with tiny holes
Often has a polyester (PET) fabric layer bonded to one side
Not environmentally friendly – difficult to recycle and doesn’t biodegrade
Some people have allergic reactions & smells odd
Wetsuits
Knee / wrist supports
Gaskets / seals
Laptop sleeves
Drink / can coolers
TPU
Properties
Uses
Thermoplastic polyurethane
An example of a thermoplastic elastomer
Good elasticity
Strong – and better abrasion resistance than rubber
Easy to process – just melt and mould/form
Quite expensive
Can yellow with UV exposure
Shoe soles
Inflatable products
Flexible 3D printing filament
Watch bands and goggle straps
Gasket: a shaped piece of material that fills the space between two surfaces to create a seal, preventing leaks of liquids, gases, or pressure. When compressed, the gasket deforms to fill every tiny microscopic gap. They are often clamped between flanges or adjoining surfaces. Examples: rubber rings to make glass jars air tight; rubber rings to stop taps leaking.
Composite materials containing plastic / polymers
COMPOSITE MATERIALS
Fibreglass
Properties
Uses
Glass fibre reinforced plastic (GRP)
Glass fibres come as a cloth or mat, providing reinforcing to polyester resin (can also involve other layers of cloth)
Lighter than steel and very strong
Can be made in a mould or applied to a frame
Boats
Water tanks
Swimming pools
Carbon fibre reinforced plastic (CFRP)
Properties
Uses
Contains tiny strands of carbon (a graphite-like material) and resin, such as epoxy resin
Very, very light and strong (stronger and stiffer than steel, yet lighter even than aluminium)
Conducts electricity
Distinctive woven black pattern created by the fibres (has become a status symbol)
Very expensive
Difficult to make
Difficult to recycle
Can be brittle and suddenly breaks (rather than bends – sudden failure)
Aeroplane bodies
Spacecraft components
Helicopter blades
Wind turbines
Racing car panels
Tennis rackets
Golf clubs
Kevlar® reinforced plastic
Properties
Uses
Kevlar® is a light and super-strong synthetic fibre, with exceptional tensile strength
Frequently used with epoxy resin to make composite products
Difficult to cut (requires special scissors)
Expensive and hard to make
Absorbs moisture (can weaken when wet)
Bulletproof vests
Army/military helmets
Chainsaw pants
Cut resistant gloves
Suspension bridge cables / elevator cables
Tennis racket strings
Braided elastic
Properties
Uses
Has a cotton or polyester outer braid with a stretchy elastane core (also known as Spandex or Lycra)
Good elasticity – can stretch 5-7 times its original length and return to original shape (outer fabric stops it over-stretching and provides structure to stitch to)
Durable and withstands repeated washing
Waist bands and other stretchy elements in clothing
Hair ties
Other composite products that use plastics include melamine coated chipboard and PE coated card.
Environmental impact of plastics
- Most plastics are made from crude oil / fossil fuels, depleting non-renewable resources
- Poor biodegradability: often take hundreds of years to break down, polluting the environment and accumulating in oceans, soil, and eco-systems
- Health risks from microplastics entering food chains & water systems
- Toxic additives: Chemicals like BPA (bisphenol A) can leach into environment and organisms
Biodegradable plastics (bioplastics)
Biodegradable plastics decompose or break down naturally as a result of microbial action.
BIODEGRADABLE PLASTICS
PLA
Properties
Uses
Polylactide (PLA)
Biodegradable plant-based thermoplastic made from fermented glucose extracted from corn / sugarcane etc
Easy to 3D print
Non-toxic
Inexpensive
Low heat resistance
Brittle
3D printed prototypes, toys, decorative items
Disposable packaging
Food safe grades can be used for food packaging
PHB
Properties
Uses
Polyhydroxybutyrate (PHB)
Plastics made from this include those under the brand name BIOPOL®
Biodegradable thermoplastic produced by bacteria fermenting organic waste
When buried in soil it breaks down very rapidly
Very brittle
Expensive to produce – often not commercially viable due to high costs
Internal stitches in wounds (dissolve naturally, no removal needed)
Compostable products
Packaging
Polymorph
Properties
Uses
Modelling plastic with very low melt point (softens in hot water) and can shape by hand
Reusable (can remelt multiple times)
Biodegradable (takes 6 months – 2 years)
Non-toxic
Expensive for large projects
Prototyping and modelling
Custom handles and grips
Repair work / temporary fixes
Arts & crafts
Props / hobby activities
While there’s growing development of bio-based plastics made from renewable sources like corn starch, sugarcane, or algae, these still represent a small fraction of total plastic production.
Recycling codes help to identify different types of plastic
The symbol indicates plastic type, it does not mean the product is made from recycled material, or that it can be recycled in your area.
Amiria has a Bachelor of Architectural Studies, Bachelor of Architecture (First Class Honours) and a Graduate Diploma of Teaching. She is a CIE Accredited Art & Design and Design & Technology Coursework Assessor. Amiria now teaches Art, Design & Technology at ACG Parnell College.