L1: Intro and Solid State Flashcards Preview

Ma ME523: Polymer And Polymer Composites > L1: Intro and Solid State > Flashcards

Flashcards in L1: Intro and Solid State Deck (40)
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1

Define polymer

Many units of monomers covalently bonded together to form a long chain (a macromolecule)

2

Give the 3 conventional classifications of polymer

-Natural
-Semi-synthetic
-Synthetic

3

What are the subdivisions of natural polymers?

Organic and inorganic

4

What are semi-synthetic polymers? Give an example

Naturally occurring polymers chemically modified to make their properties desirable
Vulcanisation of rubber

5

What are synthetic polymers?

Human made polymers, made from monomers derived from petroleum

6

Give the key characteristic of organic synthetic polymers. How do inorganic synthetic polymers differ?

Backbones have C-C bonds
No C in backbone

7

What are the two main categories of polymerisation reaction and the sub-types for each?

Chain-growth
-Free radical
-Coordination
-Cationic
-Anionic
Step-growth
-Polycondensation
-Polyaddition

8

When are brackets used in nomenclature?

When the monomer name consists of more than one word - eg poly(vinyl chloride)

9

What feature must monomers have in order to carry out chain-growth polymerisation?
What must happen to ethylene to create this feature?

Carbon-carbon double bonds ( C=C )
One or more hydrogen atoms in the ethylene monomer must be replaced by other elements or organic groups

10

Give an overview of free-radical polymerisation

1. Initiation. A free radical initiator reacts with the monomer, opening the C=C bond. One electron from the double bond is left alone - a larger free radical has been made
2. Propagation. Monomers are added to the chain one at a time
3. Termination. Two large free radical chains meet to form dead chains. Dead chain length is random

11

What is the requirement for monomers used in step-growth polymerisation?

Monomers must have 2 different functional groups (can have 2 different monomers or 1 monomer with 2 different groups)

12

Give an overview of step-growth polymerisation

Difunctional group monomers react, potentially forming H2O as a byproduct.
Intermediate medium-sized oligomers form

13

Give an overview of condensation polymerisation

An ester linkage is formed between two monomers when the -COOH and -OH groups react (can have two different monomers or a difunctional monomer). A water molecule is produced as a by-product
Chain grows from both ends of the chain

14

What does an ester linkage look like?

O
ll
- O - C -

15

Give an overview of condensation polymerisation

The hydrogen from an amine group reacts with the hydroxyl group from another monomer to form a water molecule as a by-product, linking the two monomers by an amide bond

16

What does an amide bond look like?

H O
l ll
N - C

17

What are the key features of polyaddition polymerisation?

-Difunctional groups are required
-No small molecules are formed as byproducts

18

Describe the change when a thermoplastic polymer is heated

It melts into a viscous liquid. This is a reversible change

19

Describe how heat affects liquid thermoset polymers

They are 'cured' into a hard solid. They become hard and rigid due to inter-chain cross-linking reactions

20

What is the result of polymers being polydispersed, and what must therefore be measured?

No unique molecular weight
Need to measure Molar Mass Distribution

21

Give the formula relating mass, moles and molecular mass

Mass = moles x molecular mass

22

Define degree of polymerisation (both words and equation)

-Mean number of monomer units per polymer chain
-(Molar mass of chain)/(Molar mass of monomer)

23

Why is molar mass important?

-Higher MM gives better mechanical properties due to increased chain entanglement and interaction
-More difficult to process due to increased melt viscosity

24

Give names for polymer architecture with the following structures (2 is the group of i, ii, iii):
1. -A-A-A-A-A-A
2.
i) -A-B-A-B-A-B-A-
ii) -A-A-A-A-B-B-B-B-
iii) -A-B-A-A-A-B-B-A-B

1. Homopolymer
2. Copolymer
i) Alternating
ii) Block
iii) Statistical

25

Give the names for polymers:
1. Consisting of identical monomers
2. Consisting of different monomers

1. Homopolymer
2. Copolymer

26

Describe branched polymers

Long chains of identical monomers with shorter branching chains of identical monomers

27

Describe graft polymers and give their nomenclature

Long chains of identical monomers with shorter branching chains of
different identical monomers
poly(A-g-B)

28

Describe cross-linked polymers

A 3D network of polymer chains

29

Give the 3 spatial arrangements of tacticity and a basic description

1. Isotactic - same orientation
2. Syndiotactic - Alternating orientation
3. Atactic - No regularity

30

Why can't atactic polymers crystallise?

There are steric clashes so the molecules cannot arrange themselves in an ordered fashion