Thermoplastics

Question 1

What are thermoplastics?

Answer 1

These materials can be repeatedly reheated and remoulded. They contain a tangle of long-chain molecules, which are held together by strong electrostatic force (van der Waals bonds), when released with heat they can be reshaped.

Question 2

What are van der Waals bonds?

Answer 2

A type of atomic bonding found in thermoplastics, which is an electrostatic bond that allows them to be reshape during with heat.

Question 3

What temperatures normally are thermoplastics heated at?

Answer 3

70-185°C (low melting point)

Question 4

What are some applications for improved polymer (thermoplastics)?

Answer 4

• designed to meet food quality standards, i.e. PET extends the shelf life of carbonated drinks.
• can be made to withstand higher temperatures, allowing motor cases to be moulded integrally.
• ready meals - plastic heated with food

Question 5

What are the characteristics and common uses of PC?

Answer 5

Polycarbonate:

• Good chemical resistance, expensive material
• protective shields, safety glasses, safety helmets

Question 6

What are the characteristics and common uses of ABS?

Answer 6

Acrylonitrile Butadiene Styrene:

• high impact strength, toughness,scratch-resistant, lightweight and durable
• kitchen products, mobile telephone cases, safety helmets, toys, some car parts

Question 7

What are the characteristics and common uses of CA?

Answer 7

Cellulose Acetate:

• Tough and rigid, good weight to strength ratio, transparent and non flammable
• Photographic film, cupboard door knobs, frames for glasses

Question 8

What are the characteristics and common uses of Nylon?

Answer 8

Polyamide:

• Hard, tough, resistant to wear with a low coefficient of friction
• Bearings, gears, curtain rail fittings and clothing

Question 9

What are the characteristics and common uses of PMMA?

Answer 9

(PolyMethylMethAcrylate) Acrylic :

• Food safe, tough, hard, durable, easily machined
• Light units, illuminated sign, lenses for car lights.

Question 10

What are the characteristics and common uses of PP?

Answer 10

Polypropylene:

• Lightweight, food-safe, good impact resistance even at low temperatures, good chemical resistance
• kitchen products, medical equipment, string and rope

Question 11

What are the characteristics and common uses of HIPS?

Answer 11

High Impact Polystyrene:

• Good impact resistance, good strength and stiffness, lightweight
• Toys and refrigerator linings

Question 12

What are the characteristics and common uses of PS?

Answer 12

Polystyrene:

• Lightweight, rigid, colourless, low impact strength
• Packaging, disposable cups/plates and containers

Question 13

What are some examples of non-polymer thermoplastics?

Answer 13

• clay which in wet form used for model making, ceramic figures and sculptures.
• paper can be reformed once mixed with water (and some new fibres) to make recycled paper
• metals: a good example is steel used in manufacture of cars. Once sparked from other materials, it can be heated to the melting point of steel and reshape do using one of the many process available for metals.
• glass is a very brittle materials, can be reheated to their to their melting point and reshaped.