The density of polymers

Question 1

How is low desnity polyethene produced?

Answer 1

UNDER harsh conditions (high pressure and temperature) resulting in many long branches.

Question 2

Properties of low density polyethene?

Answer 2

Low density (long branches prevents them from packing close)
Soft and low mP - weak dispersion forces as they are far apart
Non-crystaline
Non-conductors of electricity
Opaque

Question 3

Define: crystalline

Answer 3

Polymer chains are oganised in an orderly way - resulting in chains being packed together more closely

Question 4

Define: non-crystalline

Answer 4

Polymer chains are disorganised and do not pack together closely

Question 5

How is high density polyethene produced?

Answer 5

Under milder conditions (milder pressures and temperatures) resulting in far fewer branches forming.

Question 6

Properties of high density polyethene?

Answer 6

HIgh density - chains pack together closer
HIgher melting points and harder - stronger disp forces
Crystalline sections
Non-conductor of electricity

Question 7

Define: syndiotactic polymer

Answer 7

Side groups are regularly alternating - polymers can pack very tightly together (same properties as HDPE)

Question 8

Define: isotactic polymers

Answer 8

Side groups are all on one side - polymers can pack quite closely together(same properties as HDPE)

Question 9

Define: atactic polymers

Answer 9

Side groups are randomly placed on either side - polymers do not pack closely together (same properties as LDPE)