Polymers: Solid State, Synthesis & Modification Flashcards Preview

PM2B Autumn Amy L > Polymers: Solid State, Synthesis & Modification > Flashcards

Flashcards in Polymers: Solid State, Synthesis & Modification Deck (13)
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1
Q

What are the 2 types of solid state a polymer can be in?

A

Amorphous or crystalline

2
Q

Describe the crystalline solid state

A
  • Highly ordered arrays of molecules
  • Anisotropic properties
  • Definite melting point
3
Q

Describe the amorphous solid state

A
  • Randomly orientated molecules and atoms
  • Isotropic properties
  • No definite melting point
  • Some properties typical for liquid
4
Q

What is a semi-crystalline polymer?

A

Crystalline zones in an amorphous polymer

5
Q

What are the 3 physical states of amorphous polymers?

A
Glassy state (hard)
(Tg)
Rubbery state (soft)
(Tl)
Liquid state
6
Q

What does Tl represent?

A

Liquid transition point = melting point, but doesn’t technically melt

7
Q

What does Tg represent?

A

Glass transition temperature

8
Q

Describe a polymer below its Tg

A

Hard and glasy

9
Q

Describe a polymer above its Tg

A

Soft and elastic

10
Q

What can alter a polymer’s Tg?

A

When it is mixed with another substance

e.g. a drug

11
Q

What is addition polymerisation?

A

Small unsaturated monomers (C=C) join up by the opening of the double bond = a long carbon chain of single C-C bonds

12
Q

What is step growth polymerisation (polycondensation)?

A

Monomers react to first form dimers –> trimers –> longer oligomers –> long chain polymers
Monomers have 2 functional groups
H2O lost during the reaction

13
Q

What is ring-opening polymerisation (ROP)?

A

Form of chain-growth polymerisation
The terminal end of the polymer chain acts as a reactive centre where further cyclic molecules can react by opening its ring system to form a longer polymer chain