Lecture 1-2 Processes

Question 1

A polymer is

Answer 1

a compound comprised of long-chain molecules, that consist of repeating units

Question 2

Polymers can be both —- and ——

Answer 2

natural, synthetic

Question 3

Before polymerisation, the small molecules are known as

Answer 3

monomers

Question 4

Shear heat in extrusion is

Answer 4

the heat that is generated from the reduction of area and the smaller screw which forces the polymer pellets to compress and melt together

Question 5

The degree of polymerisation indicates (for a polymer)

Answer 5

indicates the average number of mers or repeating units in the polymer molecules

Question 6

List a few useful properties of engineering polymers (7)

Answer 6

• High strength to weight ratio
• Low electrical and thermal conductivity
• Resistance to corrosion and chemicals
• Low cost
• Variety of colours and transparency
• Easy processing
• Low cost

Question 7

Describe the amorphous polymer structure

Answer 7

Long chain polymers, no chemical bonding between the molecules, in “spaghetti” form

Question 8

Describe the amorphous cross linked structure

Answer 8

Shorter chains than the amorphous structure, polymer chains are bonded together, like a