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Incremental modification of styrene‐butadiene rubber with tert ‐nonyl mercaptan
Author(s) -
Uraneck C. A.,
Burleigh J. E.
Publication year - 1965
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1965.070090408
Subject(s) - styrene butadiene , autoclave , natural rubber , bottle , viscosity , polymerization , polymer , mixing (physics) , chemistry , molar mass distribution , polymer chemistry , styrene , intrinsic viscosity , mooney viscosity , materials science , organic chemistry , composite material , physics , copolymer , quantum mechanics
A model equation derived for the viscosity‐average degree of polymerization ( P̄ v ) for the incremental addition of modifiers, P̄ v = K {(exp{ arx 1 } − 1) + [2/(2 + exp { x 1 r })] a (exp{ arx 2 } − exp{ arx 1 })} 1/ a indicates a minimum should occur in a curve of P̄ v versus conversion at which the increments are added, x 1 . Incremental addition of commercial tert ‐dodecyl mercaptan in the laboratory to SBR recipes at 5°C. showed effects contrary to those predicted by the model equation, but incremental addition experiments with tert ‐nonyl mercaptans resulted in a minimum in viscosity versus x 1 curves, changed the molecular weight distribution, and required 34 wt.‐% less mercaptan than did the tert ‐dodecyl mercaptan control (all the tert ‐dodecyl mercaptan added initially). Incremental addition of tert ‐nonylmercaptan in pilot plant 20‐gal. autoclave reactors gave essentially the same results found in the laboratory bottle experiments. The stress‐strain and mixing properties of the incrementally modified polymer and the tert ‐dodecyl mercaptanmodified control were essentially the same within experimental error. Conditions required for successful application of the incremental modifier technique are given.