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Shear alignment of a swollen lamellar phase in a ternary polymer blend
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View: Figures


Image of FIG. 1.
FIG. 1.

Phase diagram for the PEE/PDMS/PEE-PDMS ternary blend reproduced from Hillmyer et al. (1999). Experiments were conducted on the samples indicated in the phase diagram with the following block copolymer concentrations: 10% (1), 11% (2), 12% (3), 15% (4), 20% (5), and 100% (6). The samples 1–3 are in the window and 4–6 exhibit lamellar morphology.

Image of FIG. 2.
FIG. 2.

Dynamic temperature ramp data (, ) for the 20% blend sample and the neat PEE-PDMS diblock copolymer . The order-disorder transition occurs at 37 °C for the blend and at 88 °C for the diblock. There is also a significant difference in the moduli of lamellar phases of the blend and the diblock.

Image of FIG. 3.
FIG. 3.

SANS patterns with steady shear for the 20% sample: (a) 0 and (b) with 180 s exposure and (c) with 720 s exposure . The beam is sent radial to the couette in (b) and (c), as depicted in the cartoon. The SANS pattern with beam sent tangentially (, 720 s exposure), is shown in (d).

Image of FIG. 4.
FIG. 4.

Steady shear data at 15 °C for ternary blends with increasing copolymer concentration from (solid symbols) into the swollen lamellae regions (open symbols): (a) stress, (b) viscosity, vs shear rate for 10% (∎), 11%(●), 12%(▴), 15%(▿), and 20%(◇) copolymer concentrations.

Image of FIG. 5.
FIG. 5.

Frequency sweep data (a) , (b) vs for the 20% sample at 15 °C (●), 20 (∎), 31 (◻), 33 (◇), 35 (◯), 37 (*), 39 (▵), 41 (▴), and 43 °C (◆), after time-temperature superposition . The critical frequencies and are identified as and , respectively.

Image of FIG. 6.
FIG. 6.

SAXS patterns from the 20% sample under shear at 26 °C, with the following frequencies: (a) 0, (b) 1, (c) 10, (d) , and (e) upon heating above the ODT (up to 45 °C) at , starting from the state (d). Cartoons indicate the relevant directions, and perpendicular (b, c) and parallel (d) alignment patterns. Beam direction is into the plane of the paper; the central black region arises from the beamstop. Upon cooling to room temperature from (e), the SAXS patterns revert to (a). The corresponding radial averages are depicted in (f). The curves are shifted vertically for the purpose of clarity.

Image of FIG. 7.
FIG. 7.

Comparison of moduli of unaligned and aligned 20% samples: the frequency sweep data at small amplitudes are presented for unaligned (∎), perpendicular, (●) and parallel (▴).

Image of FIG. 8.
FIG. 8.

SANS patterns for the 20% sample at different shear rates . All the patterns were collected in a single sequence of runs with progressively increasing rates, after giving sufficient time for equilibration at each shear rate. The progression of scattering patterns is indicative of a shear-induced isotropic-lamellar-isotropic transition.

Image of FIG. 9.
FIG. 9.

Comparison of viscosities of PEE (▴) and PDMS (◆) homopolymers with the viscosity of the aligned lamellae (●), corresponding to the plateau in the steady shear data [Fig. 4(b)]. The calculated viscosities of perfectly parallel and perfectly perpendicular layers of homopolymers are shown as solid and dashed lines. The data indicate that the observed alignment is mostly perpendicular.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Shear alignment of a swollen lamellar phase in a ternary polymer blend