Calculating Chain Length
For chain-growth polymerization, the average kinetic chain length is defined as the ratio of the number of propagation steps to the number of initiation steps:
where Rp is the rate of propagation, Ri is the rate of initiation of polymerization, and Rt is the rate of termination of the polymer chain. The second form of the equation is valid at steady-state polymerization, as the chains are being initiated at the same rate they are being terminated (Ri = Rt).
An analogous equation can be written for living polymerization, a type of addition polymerization, and is usually written as:
where 0- represents the number of monomer units consumed, and 0 the number of radicals that initiate polymerization. When the reaction goes to completion, =0, and then the kinetic chain length is equal to the number average degree of polymerization of the polymer.
Read more about this topic: Kinetic Chain Length
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