4-Urazoylbenzoic acid groups are attached to the chain ends of
polyisobutylene. The
cooperative assembling process of these polar groups is studied by DSC
and dielectric and dynamic
mechanical spectroscopy. The melting of the ordered clusters
occurs in the temperature range 380−390
K. Distortions within the U4A clusters (Σ process) are monitored
below the “melting” temperature
T
m
with dielectric spectroscopy. On a larger length scale, these
distortions also lead to stress relaxation
which can be probed by dynamic mechanical measurements. Near
T
m, the relaxation of U4A
multiplets
(α* relaxation) is detected with dielectric spectroscopy. In
this temperature range, dynamic mechanical
measurements show a transition from elastic behavior to viscous flow.
The results are rationalized with
molecular modeling calculations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.