What is Crosslinking

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What is Cross-linking ?

• Withrow University High School
• May 2008

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Cross-linking is a chemical reaction between two
polymer chains.The two polymer chains are
linked together by a cross-linker.
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Polymer Chains

• The M stands for monomer.

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Before Cross-linking
After Cross-linking
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The Cross-Linking Reaction
After (polymer chains are cross-linked)
Before (no cross-linking between polymer chains)
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The Cross-Linking Reaction
After (Highly cross-linked and really stiff)
Before (already cross-linked)
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How does cross-linking affect elasticity?
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How does cross-linking affect elasticity?

• Cross-linking improves the elasticity of the
  material up to a point.
• When polymer chains are cross-linked, they cannot
  slide away from each other when they are
  stretched. This is a good thing.
• But if there is too much cross-linking between
  the chains the ball loses its elasticity and
  therefore its bounce.

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Polymers make the best elastics
A polymer chain at rest
A force pulls and stretches the polymer chain.
A force pulls and stretches the polymer chain
When the force is removed, the polymer chain goes
back to its original shape.
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Elasticity makes the ball bouncy

• An elastic object is able to change shape and
  return to its original shape.