Dear ChE 530 students,

Greetings with the first email of the semester.

I looked back at polymer melt viscosity and molecular weight effects. I think that I provided the right description in class.

At lower molecular weights, the viscosity scales as

\eta ~ M (i.e. viscosity is proportional to molecular weight)

At higher molecular weights (above a molecular weight at which polymers become entangled), the scaling increases to

\eta ~ M^{3.4}

so an increase in molecular weight by a factor of 10 leads to an increase in viscosity of 10^{3.4} = 2512.

See everyone next week.

Prof. Greenfield

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