Polymer 2: Properties of polymer Flashcards Preview

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Flashcards in Polymer 2: Properties of polymer Deck (20):
1

What are the two different states of polymers?

1. Crystalline

2. Amorphous

2

Describe the properties of crystalline state?

1. Highly ordered arrays of molecules and atoms

2. Definite melting point

3. Anisotropic: orientations are all in different directions

3

Describe the properties of Amorphous state?

1. Randomly orientated molecules and atoms

2. No definitive melting point

3. Some properties typical for liquids

4. Isotropic properties: orientations are in the same direction

4

What is left after evaporation of KCl and a polymer like chitosan?

1. Crystals formed through low organic salts

2. Solution of chitosan will never form crystals (jelly like material)

5

How do the ranges of crystallinity range from 0% to 90%?

1. 0% Amorphous

2. 90% crystalline

6

What do the factors of crystallinity depend upon?

1. Chemical structure

2. Temperature

3. Processing conditions

4. Molecular Weight

7

What are the only polymer that can be completely crystallised?

Proteins have a perfect order at any level

8

What are the three different states for amorphous crystalline solids?

1. Glassy state

2. Rubbery state

3. Liquid state

9

How can you test the different states for amorphous crystalline solids?

Hanging a weight from the polymer and seeing how far they stretch

10

What does glass state temperature (Tg) mean?

The temperature required to turn glass from hard (glassy) to soft state (rubber)

11

Give two examples when Tg is -75 and Tg is 100?

1. Tg= -75 represents the material that forms catheters (polyisoprene)

2. Tg=100 represents polystyrene

12

What is plasticisation and what effect does it have on the glass state temperature?

1. When a substance is added that makes the material more soft such as water

2. Decreases glass transition temperature

13

When a polymer has a glass transition state of above 100 degrees and below it, what state does it bring?

1. Above Tg=100 means it's soft and rubbery

2. Below 100 degrees means it hard and glassy

14

What is addition polymerisation and give an example?

1. When you form a large macromolecule from the addition of many monomers with double bonds

2. This can be many repeating groups which leads to Poly being added to the front of the chemical name
Example: Vinyl acetate becomes poly (vinyl acetate)

15

What is step growth polymerisation?

1. When the polymer is added to water (hydrolysis)

2. Products formed are then used

Example: breast implants

16

What is Ring Opening Polymerisation?

1. Unstable ring is added alongside a catalyst and heated

2. Ring opening is formed

3. Biodegradable polymer is then formed which has applications in drug delivery

17

What is chitin?

1. Natural polymer that's found in animals such as crustaceans, fungi, insects and molluscs

2. Highly insoluble

18

What is chitosan?

1. Pharmaceutical excipient

2. Soluble in water under slightly acidic conditions as the NH2 reacts

3. Used to form capsules

19

How do you form chitosan from chitin?

1. You replace one functional group with NH2 in chitin

2. Deacetylation

20

How do you form poly (vinyl alcohol) from Poly (vinyl acetate)?

By reaction Poly (vinyl acetate) (PVA glue) with NaOH to form poly (vinyl alcohol) which is used in ocular areas to form tears