The Material Revalution

Question 0

What effect does decreasing the temperature have on a polymer chain?

Answer 0

The polymer chain will have a higher percentage of Crystalline regions. Eventually the glass transition temperature is reached (Tg) and the polymer become brittle

Question 1

How does increasing temperature effect a polymer chain?

Answer 1

By increasing the temperature the polymer gains slide over each other making it more flexible. Eventually the melting temperature is reached (Tm) which makes the polymer become a liquid

Question 2

What are the crystalline regions in a polymer chain?

Answer 2

The crystalline regions in a polymer, is the regular packing of the chains based on the regular order of the polymer

Question 3

How can chemists modified polymers?

Answer 3

• copolymerisation - introduce monomers with larger side groups pushes the polymer chains further apart, weakening the bonds between them.
• plasticisers - addition of plasticisers lower the Tg as they sit between the polymer chains allowing them to move more freely.
• cold drawing - this strengthens the polymer and allows it to be stretched

Question 4

Explain the difference between addition and condensation polymerisation

Answer 4

• addition polymerisation requires and Alkene monomer, where the double bond is broken to form a chain
• condensation polymerisation is the removal of an -OH from the carboxylic acid and an -H from the amine to produce water and an amide bond

Question 5

Give the general equation for acid hydrolysis of esters

Answer 5

Ester + water ➡️ carboxylic acid + alcohol

Question 6

Give the general equation for base hydrolysis of an eater

Answer 6

Ester + water ➡️ carboxyl salt + alcohol

Question 7

What are the conditions for acid/base hydrolysis?

Answer 7

Moderately concentrated acid/base

Reflux

Question 8

Describe the process of recrystallisation

Answer 8

1) dissolve the solid in a minimum volume of hot solvent
2) filter, and retain the filtrate
3) allow the filtrate to cool until crystals form
4) collect the crystals by vacuum filtration. Wash wish a minimal volume of gold solvent
5) dry in air, in an oven set at bellow the melting point if the crystals or in a desiccator