Chapter 9-Polymers Flashcards Preview

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Flashcards in Chapter 9-Polymers Deck (27):
1

Define a polymer

A polymer is thousands of small units strung together in one large chain

2

Define monomer

A single piece of a polymer

3

How are monomers joined together?

Polymerisation

4

Do polymers need to consist of all the same monomer?

No they can be different or they can be the same

5

Define Co-polymers

Are formed when two or more different monomers are used

6

Define thermoplastic polymers

Polymers that can be heated repeatedly and softened

7

Define thermoset polymers

Do not soften, but char when heated, they do not reshape.

8

What type of bonds do polymers require?

A double bond

9

What are the two main ways of producing polymers?

Addition polymerisation
Condensation polymerisation

10

What are two important polymers that are produced from ethene?

Low density polyethene
High density polyethene

11

Explain low density polyethene

Polymer chains support a large number of branches
-The only forces are dispersn forces so the brances keep them apart, this attraction becomes weaker as the branches become further apart.

12

Explain high density pressure polyethene

-Produced using low pressure
-Chains are very short and have very few side branches, which are held together by dispersion forces

13

What are some propertes of low denisity poly ethene

-Soft and flexible

14

What are some propertes of high denisity poly ethene

Ridgid and structured

15

Define Isotactic in regards to polymers

When side branches are arranged on the same side of the linear polymer, polymers are packed close together resulting in a high density substance .

16

Define atatic in regards to polymers

When branches occur at irregular points on both sides of the linear polymer.
Low density substance is formed.

17

What does the prescence of cross-linking affect

Elasticity and rigidity of the polymer

18

What does a small amount of cross linking produce?

An elastomer, realtively elastic

19

What does a large amount of cross linking produce?

-Produces a ridgid polymer (thermoset)

20

How does the degree of crystallinity affect the polymer?

More regions of regular arrangement increase strength

21

How does the length of the polymer affect the polymer?

The longer the chain, the smaller the polymer

22

How does the addition of plasticisers affect the polymer?

Plasticisers are small molecules in polymers to make them more flexible.

23

Do thermoplastics have cross-linking

No

24

Example of thermoplastic

Polystyrene

25

Example of thermoset

Bakelite

26

What are the only forces in polymer chains?

Dispersion forces

27

What does the addition of plasticers actually do?

Cause the polymer chains to move slightly furhthur apart resulting a more softer and flexible polymer