Polymers and Composites Flashcards
What does PVC stand for
Polyvinyl Chloride
What are polymers
Materials known as plastics and elastomers (rubber)
Basic structure of a polymer
Chain like molecular structure, with a large repetition of monomers. Made up of mainly hydrogen and carbon
What is polymerisation
The process of linking together monomers to form polymers. Accompanied by a state change from liquid/gas to solid state
Conditions required for polymerisation
-High Pressure
-High Temperature
Light
Chemical Catalyst
3 classifications of polymers
- Bio-Polymers
- Natural Polymers
- Synthetic Polymers
4 polymer structures
- Linear
- Branched
- Cross Linked
- Network
3 types of polymers and properties
- Thermoplastics- linear polymers with minor branches, can be recycled
- Thermosets- cross linked and network structure, stronger than thermoplastics, can’t be recycled
- Elastomers- rubber like carbon helical chains, elastic behaviour
What is a composite
Combination of 2 or more chemically distinct materials, which when combined have improved properties
Structure of a composite
Reinforcing Fibres
Matrix
Properties of reinforcing fibres
High strength and stiffness, low density and expensive
e.g. glass, carbon, boron
Properties of a matrix
Good shear properties, low density, cheap
e.g. polymers, metals and ceramics
3 classifications of composites
- Particle Reinforced
- Fibre Reinforced
- Structural
Advantages of Composites
- Design Flexibility- moulded into complex shapes at relatively low cost
- Corrosion Resistance-
- Durability- long life span and low maintenance
Disadvantages of Composites
- Heterogenous
- Anisotropic
- Difficult to inspect for damge
