1. A level Product Design Unit 2
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Polymers
A level Product Design
Unit 2

2. - Plasticity is a material property
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Plastic or Polymer
- Plasticity is a material property
- Plastic Materials include bone, horn, clay, concrete and polymer
A polymer can be natural & synthetic
We are only interested in synthetic polymers

3. Normally, chains are randomly arranged and form a 3d pattern
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Polymer structures
Polymer molecules are made up of numerous monomer (individual molecules) which are linked together to form a chain
A chemical reaction forms the polymer molecule (makes the chain) - polymerisation
Normally, chains are randomly arranged and form a 3d pattern

4. This chain length has an effect on the polymers properties such as Tg
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Polymer Properties
If you uncoiled one polymer molecule’s chain its length may be 10,000 times the diameter of the chain
This chain length has an effect on the polymers properties such as Tg
Tg = glass transition temperature
Temperature at which polymer moves from a hard glass like state to a softer rubbery state

5. To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Plastic additives
Different ‘additives can be altered in a polymer to has additional effect on its properties
Reinforcement
Added to improve material strength properties
Plasticizer
Added to make material easier to process
Filler
Added to replace polymer and reduce cost
Stabilizers
Stop deterioriating over time
Heat, UV, Biodegradation
Foamants
Increases volume
Gives more elasticity
Typical PVC Content

6. Cross-linked polymers
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Cross-linked polymers
These have strong bonds between chains (crosslinks) and intra-chain
Thermosetting plastics (eg Araldite) are highly linked which results in
Chemical reaction forms the links (resin mixed with activator)
One way process – cannot be reversed
Will not soften with heat - very high Tg
Materials like rubbers are lightly crosslinked

7. - However weak bonds (Van dar Waals forces) between chains
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Thermoplastics
- These are strong covalent bonds (bonds between individual elements in chain)
- However weak bonds (Van dar Waals forces) between chains
- This mean that with heat they have a high plasticity
Thermoplastic can be recyclable by re-heating

8. There are two groups of thermoplastics Amorphous thermoplastics
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
There are two groups of thermoplastics
Amorphous thermoplastics
Chains are randomly entangled
Generally transparent
Eg. PolyCarbonate (CDs)
Glass transition temperature (Tg) is a key property
Semi-crystalline thermoplastics
Cooling causes molecules to fold in a regular structure and form a crystal
Crystal is dense and so plastic is opaque
Eg. Polyethylene (gas and water pipes)
Have a definite melting point (Tm)

9. Amorphous thermoplastics There have:
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Amorphous thermoplastics
There have:
Good resistance against medium temperatures (< 1000C)
Hard
Tough
antistatic.
good resistance against chemicals.
Poor resistance to UV-light
Can be painted
Semi- crystalline thermoplastics
The more crystalline a material is:
The stronger it gets
It has more resistance to solvents
Higher density
Higher stiffness
Higher melting point (Tm)
The lower its transparency
Reduced impact resistance (brittle)
Reduced ductility

10. Effect of temperature on thermoplastics
To understand the molecular structure of polymers and how it has an effect on its properties
To identify a range of different polymers and their applications
Effect of temperature on thermoplastics Tg
(glass to rubber) Tm
(melting point)
Stiffness
(modulus)
Temperature
Amorphous thermoplastic
Semi-crystalline thermoplastic

11. Polyurethane
Urea formaldehyde (UF)
Phenol Formaldehyde (PF)
Epoxy Resin
Melamine formaldhyde
PolyPropylene (PP)
Poly Vinyl Chloride (PVC)
PolyStyrene (PS)
Acrylic
HDPE (High Density PE)
LDPE (low Density PE)
PET (PE Terephthalate)
ABS (Acrylonitrile Butadiene Styrene)