MatSE443:
Introduction to the Materials Science of Polymers
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All paragraph and pages numbers refer to the primary text (Painter & Coleman) Study Guide (chapter 4)
Concepts that you must know:
Definition of 'extend of reaction' (p), also as a probability.
Statistics of Polycondensation: average molecular weights (Mn, Mw) as
a function of the 'extend of reaction' (p), polydispersity as function of p
Mole fraction & Weight fraction of x-mers in polycondensation
Know how to apply Equations: 4.5 (4.25), 4.28, and 4.29, if given the
p, or the concentrations (initial and at p) of functional groups
Exercises:
*Go through the derivations of Mn(p) (pg. 86), and Mn(p,r) (pg. 88)
*Go through the derivation of the Mole fraction & Weight fraction (pg.
89-91)
*Do "study question" 4 (pg. 105); make sure you can address 4c
Interactive Module:
You need the
latest plugin
(Flash Player version 6) (which can be obtained free from here)
The files are extremely small (typically half a minute with a modem) and
can be run directly from this web-page.
Start by showing one curve (mole/weight fraction) at a time and
observe how each curve changes with p (move the slider). Plot both
curves and compare their
shapes and positions. (can you connect it back to the definitions of Mn and
Mw from chapter 1?)
Comment on how the values of Mw, Mn, and d depend on the "extend of the
reaction" (p).
Which molecule size has the largest mole fraction at any
instant in the reaction (p)? Which molecule size has the largest weight
fraction at any instant in the reaction (p)? Comment on the two!
