Viscosity Index Improvers and Other Applications

Ethylene-propylene copolymers, acrylates and polyisobutylene are the most common competitors to block copolymers in these markets. The narrow molecular weight distributions and star architecture of the SBCs give them a better balance of properties at molecular weights of 100000 than the competing polymers. 

Holden, H. E. Schroeder, eds, Thermoplastic Elastomers, a Comprehensive Review, Hanser, Munich, 1987, 2nd edn A. Noshay, J. E. McGrath, Block Copolymers, Overview and Critical Survey, Academic Press, New York, 1977 G. Holden, Thermoplastic Elastomers, Hanser Munich, 2000 R. P. Quirk, D. J. Kinning, L. J. Fetters, in Comprehensive Polymer Science, G. Allen, J. C Bevington, S. L. Aggarw al, eds, Pergamon Press, Oxford, 1989 P. Dreyfuss, L. J. Fetters, D. R. Hansen, Rubb. Chem. Technol., 53 (1980). 

Anionic Polymerization, Marcel Dekker, New York, 1996 J. E. McGrath, ed., Anionic Polymerization, Kinetics, Mechanisms, and Synthesis, ACS Symposium Series 166, American Chemical Society, Washington, DC, 1981 M. Morton, Anionic Polymerization Principles and Practice, Academic Press, New York, 1983. 

Principles of Polymerization, 2nd edn, Wiley-Interscience, New York, 1981, pp. 377-378, 388-389. 

This relationship holds for monofunctional initiators. If an initiator starts n chains, Xn = [M]/ i[I]. 

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