Material

Thermoplastic elastomers are available in hardnesses from 35º Shore A to 80º Shore D. They can be used as a replacement for vulcanized rubber, as well as softened PVC. The greatest advantage of TPE materials compared to vulcanized rubber is that they can be shaped in an easy way, such as by extrusion and injection moulding. Moreover, waste can be recycled. There are a number of variants of TPE with various substances as “carriers”, and there are characteristic differences between these.

Advantages:

• Broad hardness interval
• Good flexibility at low temperatures
• An environmentally friendly alternative in many cases
• Waste can be recycled
• Can replace softened PVC or rubber
• High friction can be achieved at low shore values
• Can be enamelled with the right pre-treatment

Limitations:

• Relatively expensive material
• Some qualities have limited chemical resistance
• Risk for settlement after compression

Abbreviation:

TPE

Colouring options:

Almost unlimited

Common applications:

Shoe soles, toothbrushes, bumpers, spoilers, buckles, ice skates, toys, etc.

Polyvinyl chloride in its pure form is a colourless polymer with a softening temperature of around 80ºC and a density of 1.4 g/cubic centimetres. Polyvinyl chloride plastic is usually mixed with various additives such as softeners, fillers, lubricants and stabilisers, which means that there are a large number of qualities with widely varying characteristics. The characteristics’ variation is highly dependent on the additives, but in purely general terms, polyvinyl chloride plastic has good chemical durability. They have a low softening point, however.

Advantages:

• By mixing in softeners, everything from a soft to a rigid thermoplastic can be obtained.
• High chemical resistance
• Rigid PVC has good dimension stability
• Low price

Limitations:

• Relatively low softening temperature
• Rigid and brittle at low temperatures
• Relatively high density relative to other thermoplastic materials
• Is corroded by ketones. Some qualities are exaggerated or degraded by chlorinated or aromatic hydrocarbons, esters, some aromatic esters or amines and nitro compounds.

Abbreviation:

PVC

Colouring options:

Almost unlimited

Common applications:

Pipes (even chemically resistant), building panels, corrugated sheets, casements, door posts, profiles, insulation material (or wire and the like), shrink hoses, bottles and containers (oil, shampoo, etc.), imitation leather (clothes and luggage), wallpaper, rigid cellular plastic (sandwich elements, insulation), soft cellular plastic (shoe soles, toys, synthetic leather), etc.

Polystyrene is a clear, colourless, hard and rigid thermoplastic. Polystyrene softens at 100ºC and has a density of 1.05 g/cubic centimetre. The benefits of polystyrene plastic include hardness and rigidity, low shape shrinkage, low water absorption, good insulating characteristics and a relatively low price. However, it is brittle and sensitive to UV light, has poor chemical durability and has a somewhat low softening temperature. PS also has a low resistance to oils and solvents.

Advantages:

• Hard and rigid material
• Unlimited dyeing potential
• Available in various levels of quality
• Low water absorption
• Good electrical insulation characteristics
• Low formwork drying shrinkage
• Low price

Limitations:

• Brittle
• Low softening temperature
• Tendency to form micro-stress fissures
• Low resistance to oils and solvents
• Yellows and becomes brittle outdoors (UV radiation)

Abbreviation:

PS

Colouring options:

Unlimited

Common applications:

Packaging, disposables (cups, spoons, etc.), household items, cellular plastic, etc.

Polypropylene, without additives is white to colourless, similar to polyethylene but more rigid. Good mechanical characteristics even at high temperatures. High fatigue strength, low density 0.90 g/cubic centimetre, good electrical characteristics, good chemical resistance and good mechanical characteristics make propylene plastic usable in a number of different contexts, especially were high demands are set on temperature resistance and mechanical stability. Propylene plastic is often in copolymers with ethylene, which results in better low-temperature characteristics (especially impact strength). The same effect is achieved by mixing in small amounts of rubber, e.g. EPDM in the homopolymer. PP is readily broken down by UV radiation and must be stabilised for outdoor use.

Advantages:

• High fatigue strength
• More rigid than HDPE. There are filled and reinforced qualities with e.g. chalk, talc and fibre glass that compete with ABS
• Maintains its mechanical characteristics better at high temperatures than HDPE
• Low density 900-910 kg/m3
• Chemical resistance similar to that of polyethylene, but not the same tendency to stress crack formation
• Mechanical and electrical characteristics are also retained in water

Limitations:

• Becomes brittle below -20ºC
• Broken down by UV radiation if it is not stabilised
• Is attacked by oxidizing acids
• Heat stability is reduced in contact with copper
• Easier to glue together with other materials, such as wood and aluminium than with itself

Abbreviation:

PP

Colouring options:

Unlimited

Common applications:

Fan propellers, car grills, instrument panels, chassis, bottles, containers, pipes, wheels, door handles, casings for kitchen appliances and hairdryers, rope, medicine and cosmetics packaging, electrical insulation details, toolboxes, etc.

Comment:

Available as homopolymers and copolymers. The copolymer PP-PE has better impact strength in cold than the homopolymer PP. PP is suitable for injection moulding, thermoforming, blow moulding and extrusion and can be stamped, welded, foiled and vacuum-metallised. 

Polycarbonate plastic is a hard and rigid, but very impact resistant thermoplastic. Polycarbonate plastic has very high impact strength, which is retains even at low temperatures down to -40ºC. However, it is sensitive to incipient fractures and microfissures, as well as scratches. PC has good electrical characteristics and good dimension stability. Untreated, the plastic is clear and colourless. Moisture uptake is low and weather durability is good. However, elevated temperatures (60-70ºC or higher) combined with moisture can cause some brittleness. It has relatively good chemical resistance, although it is corroded by strong acids and bases, aromatic and chlorinated hydrocarbons and methanol. Compounds of PC and ABS are available as polymer alloys.

Advantages:

• Extremely high impact strength, even at low temperatures
• Can be obtained glass clear
• Dimension-stable material
• Can be reinforced (e.g. with fibre glass)
• Resistant to weak acids, aliphatic hydrocarbons, paraffin, alcohols (except methanol), animal and vegetable oils and fats
• Good outdoor durability

Limitations:

• Cannot be used in warm water over 60ºC (continuously)
• Poor scratch resistance
• Corroded by oxidizing acids, bases, ammoniac, methanol, aromatic and chlorinated hydrocarbons
• Sensitive to incipient fractures and microfissure formation

Abbreviations:

PC

Common applications:

Pump wheel, propellers, protective helmets, vandal-proofing window panes and glass for outdoor fixtures, protective glass for tail lights on cars, film cassettes, magnet valves, high voltage fixtures, hair dryers, contact lenses, relays, etc.

Polyethylene is a white, colourless thermoplastic that is available in a few variants with different characteristics, the most common of which are:

• LD (low density)-polyethylene: Density 0.910 – 0.940 g/cubic centimetre.
• HD (high density)-polyethylene: Density 0.940 – 0.965 g/cubic centimetre.
• HD polyethylene is more rigid and has a harder surface than LD polyethylene.

Polyethylene is relatively resistant to chemicals (with the exception of strong oxidizing acids and some organic solvents), has low water absorption and can be used together with food. It is also light weight and has good impact strength and a relatively low price. However, PE burns easily and has poor weather durability in its unpigmented form and limited heat resistance. It is also very difficult to glue and difficult to print on. PE has a high linear heat expansion coefficient and low resistance to creeping. The mechanical characteristics are also strongly temperature dependent.

Advantages:

• Very good impact strength across a wide temperature range
• Low water absorption
• Resistant to most chemicals
• Can be used in contact with food
• Is available in multiple variants with varying melting indexes and molecular weights from very weak to semi-rigid material
• Rendered more rigid with fillers or fibre glass
• Low price

Limitations:

• Very high coefficient of longitudinal expansion
• Low resistance to creep under load
• Poor fatigue strength than polypropylene
• Burns fiercely High shape shrinkage
• Sensitive to stress corrosion
• Poor weather resistance (if not black)
• Low scratch resistance
• Mechanical properties strongly temperature dependent

Abbreviation:

PE

Colouring options

Unlimited

Common applications:

Household items, toys, bottles, pipes, buckets, accumulator containers, cable insulation, petrol tanks, packaging film, containers, linings, sealing rings, etc. Note: Also available in a mid-density (MD) variant, which is not very common, however. 

Polyamide plastics have good mechanical characteristics. They are tough with good fatigue and creep characteristics, have a low friction coefficient and are resistant to wear. They are resistant to many solvents, including chlorinated hydrocarbons, alcohols and esters. They are also resistant to most bases. However, PA cannot handle strong acids and strong oxidising agents, such as chlorine and aromatic alcohols. Polyamide plastics take up water. It acts as a softening agent and changes the material’s dimensions and characteristics. Among other aspects, the electrical characteristics are affected, which is why their use as electrical insulators is not recommended. Destabilising qualities of PA are sensitive to UV light and heat. With fibre glass, greater tensile strength and rigidity can be achieved. The dimension stability also increases and moisture uptake decreases.

Advantages:

• Good combination of mechanical and chemical characteristics.
• Good wear resistance
• Withstands relatively high temperatures
• Can be steam sterilised
• Good chemical resistance
• Some characteristics can be improved with the help of fillers

Limitations:

• All polyamides absorb or emit moisture, which changes the material’s characteristics.
• Linear expansion varies with temperature and moisture content.
• UV radiation makes polyamides brittle.
• Corroded by strong mineral acids and acetic acid, dissolved by phenols. Some types are corroded by formic acid.

Abbreviations:

PA

Colouring options

Almost unlimited

Common applications

Gear wheels, screws, bearings, propellers, machine hoods, etc. Note: Available in many variants, e.g. PA 6, 6.6, 6.10, 12, etc.

In general, ABS has good impact strength, hardness and relatively good chemical durability. However, it is not durable outdoors. ABS has a softening point at between 85ºC and 110ºC depending on quality. ABS can be reinforced with fibre glass, giving it 2-3 times more rigidity (E module). ABS can be electroplated (chromed).

Advantages:

• Good combination of mechanical and chemical characteristics at a relatively low price
• High impact strength, surface hardness and surface finish
• Low formwork drying shrinkage
• Good low-temperature characteristics
• Available in various levels of quality
• Reinforced with fibre glass, it is 2-3 times more rigid
• Upon expansion, a cell structure is achieved
• Can be electroplated and chromed
• Easy to glue and weld

Limitations:

• Limited weather durability (yellows, ages and becomes brittle)
• Low resistance to certain solvents
• Sensitive to oxidising agents

Abbreviation:

ABS

Colouring options

Unlimited

Common applications

Telephone hoods, vacuum hoods, kitchen appliances, instrument panels, toys, furniture, car grills, office machines, car bodies, industrial parts, etc