Questions from class - Lecture 9 Flashcards
1
Q
What is the intrinsic viscosity and how is it related to the molecular weight of the polymer?
A
The intrinsic viscosity is the solute’s contribution to the viscosity of a solution. It is defined:
[eta] = lim eta_sp / c, as c -> 0
eta_sp = eta_r - 1 = (eta - eta_s / eta_s)
where eta is the solution viscosity, eta_s is the solvent viscosity and eta_r is the relative viscosity (eta/eta_s). eta_sp is called the specific viscosity.
2
Q
What is subdiffusive motion of the chain, and why does it appear?
A
?
3
Q
Which polymer systems are described by de Gennes’ reptation model? How do the time of reptation and viscosity scale with molecular weight?
A
It describes linear polymers.
The time of reptation scales with M^3. The viscosity scales (from experiments) with M^3,4.
