1 research outputs found
Strain-Induced Deformation of Glassy Spherical Microdomains in Elastomeric Triblock Copolymer Films: Time-Resolved 2d-SAXS Measurements under Stretched State
We
have found extremely low efficiency of the elastomeric properties
for SEBS (polystyrene-<i>block</i>-poly(ethylene-<i>co</i>-butylene)-<i>block</i>-polystyrene) triblock
copolymers having short polystyrene (PS) block chains. Since the SEBS
specimens form spherical PS microdomains embedded in the matrix of
the rubbery poly(ethylene-<i>co</i>-butylene) (PEB) chains,
they exhibit elastomeric properties (thermoplastic elastomer film).
However, it was found that the stress was dramatically decreased with
time when the specimens were stretched and fixed at strain of 4.0.
Furthermore, they showed macroscopic fracture with very short-term
duration (400 s to 2 h). To reveal the reason for such low efficiency,
we conducted time-resolved two-dimensional small-angle X-ray scattering
(2d-SAXS) measurements for the SEBS triblock copolymer films under
stretched state at strain of 4.0. Upon stretching, the strain-induced
deformation (not fracture) of glassy microdomains was observed. In
addition, the deformation of glassy microdomains was found to proceed
as time elapsed. Since this deformation of the glassy PS microdomains
is considered to result in such the low efficiency of the elastomeric
properties, characteristic times related to the deformation and the
stress relaxation were evaluated from the change in strain of the
glassy microdomains and from the stress relaxation curves, respectively.
Then, good agreements of the characteristic times were found, and
therefore it was concluded that the deformation of the glassy microdomains
has a strong correlation with the stress relaxation and therefore
with the fracture of the elastomeric film specimen