Page 408 - Elements of Chemical Reaction Engineering Ebook
P. 408
Sec. 7.3 Polymerization 379
Figure 7-9 Live polymer concentration as a function of chain length at different
scaled times.
Neglecting the rate of chain transfer to the monomer with respect to the
rate of propagation, a =ole balance on the monomer gives
(7 -67)
Knowing the initial monomer concentration, Mo, we can solve for the mono-
mer concentration at any time:
We can also evaluate the scaled time 0:
Relationship
between tlhe scaled
time, 0, and real (7-69)
time t
One can now substitute Equation (7-69) into Equation (7-66) to determine the
live polymer concentrations at any time 1.
For anionic polymerization, termination can occur by neutralizing the
live polymer RJ lo PJ.
Example 7-5 Calculating the Distribution Parameters @om Analytical
Expressions for Anionic Polymerization
Cdculi%te pn , pm , and D for the live polymer chains I?,.