Materials: Topic 4, Polymeric Materials

Question 1

What are the ingredients for a polymer?

Answer 1

• Carbon
• Hydrogen
• Oxygen
• One or two other odd elements!

Question 2

What are the ingredients for a good time?

Answer 2

https://www.youtube.com/watch?v=ZIesCd4I4hU

Question 3

Where do polymers come from?

Answer 3

• OIL – raw material

* OIL – energy source for manufacturing and transport

Question 4

Are all plastics exactly the same price?

Answer 4

No. Of course not you moron. 
• Depend on:
– Scarcity
– Amount purchased
– Properties required
• Engineering polymers – expensive
• Commodity polymers – cheaper

Question 5

Summary of using plastics compared to metals:

Answer 5

Expensive raw material compared to metals
• BUT - Low density material
• BUT - Cheap manufacturing routes, especially at high production volume
• BUT - Sophisticated products without
excessive added costs.

Question 6

To make things out of thermoplastics

Answer 6

• heat granules up to viscous liquid and then reshape them and allow them to cool: e.g Injection moulding
• or form sheets or preforms and then reform them in the
  viscoelastic state: e.g. blow moulding or vacuum forming

Question 7

To make things out of thermosets

Answer 7

– Create the form and then initiate curing with heat or chemicals: e.g resin transfer moulding or compression moulding

Question 8

Popular plastics?

Answer 8

Most plastics are thermoplastics:

– Polyethylene (PE): e.g. carrier bag
– Polypropylene (PP): e.g. lemonade bottle
– Polyvinylchloride (PVC): e.g.windowframes
– Polystyrene (PS) : e.g. CD Jewell case

account for 93% of the polymer market - the commodity
plastics – competing on price not properties

Question 9

Thermoplastic overview

Answer 9

• Tough – spaghetti like mass of loosely
bonded molecules
– Not all the chains are the same length
• Limited high temperature properties
– Softens into a liquid over a large temp. range
• Relatively cheap
• Examples are:
– Polyethylene - eg carrier bags
– Polypropylene – eg kettles, washing up bowls
– Polycarbonate – eg spectacle lenses

Question 10

Thermoset Overview

Answer 10

Strong (cross linked molecules)
• Good high temperature properties
– In service degrades before it melts
• Expensive
• Examples are:
– Epoxy eg Araldite two part glue
– Polyurethane – e.g. shoe soles
– Phenolics – e.g. electrical mouldings

Question 11

What is a bioplastic?

Answer 11

A plastic that is:

• Biodegradable
• Has bio-based content
• Or both