Chemistry- Polymers
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definition of polymer
“many units”
what is a polymer?
A very long molecule made up of many units
What makes up a polymer?
monomer
draw down the formula to present polymers:
what do the properties of polymers depend on?
1- Where the monomers are made from 2- condition polymer is made in
What are the two types of polymers?
Low density poly (ethene) High density poly (ethene)
The properties of a Low Density Poly (ethene)
• flexible • can make film • unreactive
The properties of High Density Poly (ethene)
• flexible • resistant to chemicals • strong
What are the two types of plastics?
• Thermosoftening • Thermosetting
Draw Thermosoftening plastics structure:
Draw Thermosetting plastic structure:
Do Thermosoftening plastics melt when heated?
Yes, they do melt remember this as they are “soft” they can melt easily
Do thermosetting plastics melt?
NO, think of this as the setting of your phone and how you cant remove it from your phone
What is a composite material?
two or more materials with different properties
What are most Composite Materials made of?
• Reinforcement (main material) • Matrix (hold the main material together)
Examples of Composite materials?
• Chipboard: Made of Wood chips held by glue • Reinforced concrete:made of steel roads and surrounded by concrete
Polymers are Giant Covalent networks true or false?
False.
why is poly (ethene) a solid at room temperature but carbon dioxide is a gas?
its a solid because its long chains are eld by strong forces. carbon dioxide is a gas because its small molecules have weak forces and spread out easily
Name the forces that act between polymer molecules. and are they weak or strong
intermolecular forces that are strong so they are solids at room temp
What determines the properties of polymers?
The structure of the polymer and the type of bonding between monomers determine its properties.
What are thermosetting polymers?
Thermosetting polymers harden when heated and cannot be reshaped.
What are thermosoftening polymers?
Thermosoftening polymers soften when heated and can be reshaped.
What do we mean by “matrix” in a composite material?
The matrix is the material that holds the reinforcement (like fibers) in place in a composite.