HS2004_2339 Week 4 Asyn_Mechansisms of Decay in polymers Flashcards

1
Q

How free radicals create more free radicals

A
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2
Q

What is a free radical

A
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3
Q

Diagram showing how different energies are required for free radical production

A
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4
Q

Scheme of reaction of free radicals

A
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5
Q

Free radicals in polymer chains: stage one: Abstraction: free radicals

A
  • an attack on the C-H bond, producing two free radicals, one on the carbon chain
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6
Q

Stage two of free radical production on polymer chains (formation of a peroxy radical)

A
  • hydrogen abstracted, creating a free radical, this is how polymers decay
  • this can react with oxygen, to stabilise via covalent bonding, but the oxygen remains a free radical (this is called a peroxy radical)
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7
Q

Stage three of free radical production in polymers: Abstraction

A

A weaker hydrogen bond is targeted, and pulled in

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8
Q

Free radical oxyl group causing chain scission (diagram)

A
  • creates an oxyl radical
  • reaction depends on energy and structure
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9
Q

Polymer decay reactions, which are non free- radical and non homolytic

A
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10
Q

Diagram showing side chain loss in polyvinyl acetate- what is the Physical change?

A

yellowing in polymer

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11
Q

Diagram of cyclisation in polymer decay

A
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12
Q

How heat and oxygen causes degradation of polymers and free radical formation

A
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