Strain-Induced Deformation of Glassy Spherical Microdomains
in Elastomeric Triblock Copolymer Films: Simultaneous Measurements
of a Stress–Strain Curve with 2d-SAXS Patterns
Shogo Tomita
Li Lei
Yoshimasa Urushihara
Shigeo Kuwamoto
Tadashi Matsushita
Naoki Sakamoto
Sono Sasaki
Shinichi Sakurai
10.1021/acs.macromol.6b02206.s001
https://acs.figshare.com/articles/journal_contribution/Strain-Induced_Deformation_of_Glassy_Spherical_Microdomains_in_Elastomeric_Triblock_Copolymer_Films_Simultaneous_Measurements_of_a_Stress_Strain_Curve_with_2d-SAXS_Patterns/4541245
Thermoplastic elastomers are elastomeric
materials which contain
hard domains as physical cross-linking for rubbery chains. Therefore,
the hard domains are required permanently rigid. Nevertheless, we
have found experimentally deformation of the hard domains upon uniaxial
stretching of the thermoplastic elastomer films. In this paper, we
report experimental results of deformation of glassy spherical microdomains
in elastomeric triblock copolymer films upon uniaxial stretching,
as revealed by two-dimensional small-angle X-ray scattering (2d-SAXS)
measurements. Actually, shifts of the peak position of the particle
scattering toward lower and higher <i>q</i>-regions were
detected for <b>q</b> directions parallel and perpendicular
to the stretching direction (SD), respectively, where <b>q</b> stands for the scattering vector. By assuming that spheres simply
deformed into prolate spheroids with its major axis parallel to SD,
1d-SAXS profiles measured at several strains were successfully reproduced
with model calculation of the 1d-SAXS profile. From the results of
model calculation, radii of the prolate spheroids were appropriately
determined. Since the extent of the deformation of microdomains was
found to increase as the initial size of microdomains decreased, it
is concluded that the deformation of glassy microdomains may be due
to a high extent of the stress concentration at microdomains. Upon
unloading, the deformed particle scattering peak in the 2d-SAXS pattern
was found to retrieve almost a round shape. At a glance, this fact
implies that the deformed sphere (prolate spheroid) recovers an isotropic
shape. However, this kind of the elastic behavior cannot be the case
for the glassy domain. Alternatively, we have tried to explain the
change of the 2d-SAXS pattern by orientational relaxation of the prolate
spheroids without changing the shape of the prolate spheroids. It
was found that such trial was sound.
2017-01-11 17:48:33
2 d-SAXS Patterns Thermoplastic elastomers
deformation
prolate spheroids
microdomain
1 d-SAXS profile
1 d-SAXS profiles
SD
Elastomeric Triblock Copolymer Films
2 d-SAXS pattern
elastomeric triblock copolymer films
model calculation