Relaxation Modulus Ert: Time and Temp Dependence

1
Relaxation Modulus Er(t) Time and Temp Dependence
Lowest T T ltlt Tg
Glassy
Leathery
Rubbery plateau
Rubbery flow
Highest T T gt Tg
Viscous Flow (liquid)
Log time
Tm
temp
Tg

• Decrease Er (t) with increase temp.
• Significant decrease of Er (t) at T ? Tg and Tm

• Decrease Er (t) with increase time
• decrease is greater at higher T.

2

• Glassy
• T ltlt Tg
• Er(t) E (elastic modulus)
• ____________________________, elastic solid
• Leathery/Glass transition region
• Large decrease in Er(t) at Tg
• viscoelastic solid (viscoelastic)
• Rubbery plateau
• Er(t) plateaus, low
• Rubbery liquid (viscoelastic)
• _______________________________________
• Rubbery flow region
• Very viscous liquid (viscoelastic)
• ________________________________________
• _________________________________________

PS
Glassy
Leathery
Rubbery plateau
Rubbery flow
Viscous Flow (liquid)
Tm
temp
Tg
What happens at molecular level? Behaves like?