RATE OF POLYMERIZATION INITIATION l Initiation of the

RATE OF POLYMERIZATION INITIATION l Initiation of the free radical involves two steps. l 1. I n. R l. Where ln is the number of free radical formed. l. Usually n = 1 or 2. l 2. R + M RM 1 l. Where l. M = R. U. Or monomer molecules. l. The first step is the rate controlling step. l d[Ro] l R i = ________ rate of initiation. l dt

PROPAGATION l l Kp M i + M M i+1 l. Where lkp = rate constant for propagation. l. Rate of consumption of monomer is l - d[M] l _____ = k [M ][M] +. . . . p 1 p 2 p i l dt l l = kp [M]([M 1] +[M 2] +. . +[M i] +. . ) l. If [M ] = total concentration of all radical species. l = [M i] l. Then l - d[M] l ______ = kp [M][M ] l dt We assume the amount of the monomer consumed in the initiation stage in negligible compared to that consumed by the growing chains.

Termination la. Termination by combination l l M i lb. + M j l. The l 2 l l M i + M j Ktd Mi+MJ overall termination rate - d[M ] ______ dt = 2 ktc [M ] + 2 ktd [M ] because two active centers die simultaneously - d[M ] ______ Where l Mi+J Termination by Disproportionation l l Ktc dt = 2 kt [M ]2 kt = ktc + ktd Both occur to gather

Thank You See You Next Lecture