Wednesday, May 25, 2011

Degree of Polymerization

Polymerization can occur in several ways:
If transfer reactions are negligible, the temperature coefficient of molecular weight depends on the initiation process. If an initiator is used, it follows from the equation below, by virtue of the differential from d ln k/dT = E RT2.

Absolute Rates:
The activation energies and frequency factors for propagation and termination can be separated if the individual rate constants are known. For most monomers Ep is near 30 kJ/mole and E, varies from 12 to 20 kJ/mole. The frequency factor vary rather widely, suggesting that steric effects are more important than activation energies in setting the value of the rate constants. 

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