is intrinsic viscosity.
is a scalar which relates to the "stiffness"
of the polymer chains. If in solution, the polymer molecules are
rigid rods, then a=2. On the other extreme, if the polymers are hard
sphere, a=0. If a=1, the polymers are semicoils. In a
Flory theta solvent, a=0.5, and in a thermodynamically
good solvent,
a=0.8. [Sperling- 105] and K
it is easy to take
the values from an intrinsic viscosity experiment
and calculate 
.
But if you're the first person to do the viscosity experiment on your polymer, then you don't have a and K available...
- [Sperling-104] says it is acceptable to take standards of your new
polymer with known
light scattering,
and do experiments from these to determine
a and K,
provided that the fractions you test have narrow molecular weight
distributions.
You can take the log of your values for
and the log of your values for
, and make a plot, with the log of viscosity as the y axis and the
log of M(w) as the x axis.As you can see from the linear equation, the slope of your line will give you a and the antilog of the y-intercept will give you K. Thanks to Peter Almond of Leeds for correcting a mistake here.
