MOLECULAR WEIGHT CONTROL OF ELASTOMERS PREPARED BY EMULSION POLYMERIZATION.

Control of mol. wt is a prerequisite for the production of commercial polymers. This is especially true of elastomers for which satisfactory processing is either an implied or a formal specification. This review-paper covers the theories and their applications for the control of mol. wts for the production of SBR emulsion butadiene rubber (E-BR), nitrile-butadiene rubber (NBR), chloroprene rubber (CR), acrylic-butadiene rubber (ABR), and acrylic rubber. The complexity of the emulsion polymerization system is reflected in the large number of experimental and theoretical studies. In this bibliography-based review the broad features of the mechanism first proposed by Harkins and the hypothesis of Smith and Ewart are accepted. The derivation of modifier depletion and mol. wt equations and the calculation of the theoretical curves used in emulsion systems for the preparation of elastomers are also presented.