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Basis for Analysis of Polymerization Kinetics

The kinetics of polymerization are of prime interest from two viewpoints. The practical synthesis of high polymers requires a knowledge of the kinetics of the polymerization reaction. From the theoretical viewpoint the significant differences between step and chain polymerizations reside in large part in their respective kinetic features. [Pg.40]

Step polymerization proceeds by a relatively slow increase in molecular weight of the polymer. Consider the synthesis of a polyester from a diol and a diacid. The first step is the reaction of the diol and diacid monomers to form dimer  [Pg.40]

The dimer then forms trimer by reaction with diol monomer [Pg.40]

Dimer reacts with itself to form tetramer  [Pg.40]

The tetramer and trimer proceed to react with themselves, with each other, and with monomer and dimer. The polymerization proceeds in this stepwise manner with the molecular weight of the polymer continuously increasing with time (conversion). Step polymerizations are characterized hy the disappearance of monomer early in the reaction far before the production of any polymer of sufficiently high molecular weight (approximately 5000-10,000) to he of practical utility. Thus for most step polymerizations there is less than 1% of the original monomer remaining at a point where the average polymer chain contains only 10 monomer units. As will he seen in Chap. 3, the situation is quite different in the case of chain polymerization. [Pg.41]


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