Polyisobutylene (PIB) was the first polymer whose viscoelastic behavio
r was thoroughly studied. The measurements made worldwide on the PIB s
ample distributed from the National Bureau of Standards were compiled
and analyzed by Bob Marvin. The superposition of the data substantiate
d the time-temperature reduction process, which was suggested by Herbe
rt Leaderman, first put into practice by Arthur Tobolsky, and given a
theoretical foundation by John Ferry. Polymers that behaved in a like
manner were called thermorheologically simple by A. J. Staverman and F
. Schwarzl. Subsequently the behavior of PIB has been found to be the
exception rather than the rule. The various deviations for this simpli
city are briefly reviewed and PIB is reexamined. (C) 1996 Society of R
heology.