Effects of morphology on mechanical properties of styrene-butadiene-styrene triblock copolymer/methyl methacrylate styrene copolymer blends

Yamaoka, Ikuro

doi:10.1016/s0032-3861(96)00381-3

Cited by 10 publications

(4 citation statements)

References 25 publications

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“…While the high shear and elongational forces developed during melt processing are largely able to disperse block copolymers in the long PS homopolymer matrix, these dispersions are only preserved if the blend is rapidly quenched after processing. Similar suppression of macrophase separation by processing was previously reported by Yamaoka for SB/poly(methyl methacrylate) blends and by Adhikari et al for S/B linear , and star − copolymers blended with a PS twice shorter than the one studied here. In the latter studies, however, injection molding was found to produce partially macrophase separated structures and injected tensile specimens were opaque.…”

Section: Resultssupporting

confidence: 91%

Styrene−Butadiene Gradient Block Copolymers for Transparent Impact Polystyrene

et al. 2008

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The mechanical behavior of styrene/butadiene triblock copolymers and their blends with high molecular weight polystyrene (PS) homopolymer was studied. Symmetric triblock copolymers with two PS end blocks of equal length (SBS) were compared with asymmetric triblocks with end blocks of different lengths (S1BS2) and with asymmetric triblocks comprising a styrene/butadiene composition gradient in the middle block (S1GS2). The precise molecular architecture of these copolymers and its role on morphology and properties were described elsewhere (Macromolecules2007402432.). Here, immiscible blends of these copolymers with long PS chains are discussed. While solvent casting yields the expected phase separation, melt extrusion produces tough and transparent blends with metastable submicrometer scale dispersions of soft microdomains highly controlled by processing. The particular molecular architecture of gradient asymmetric triblocks significantly improves ductility of these nanostructured blends. The volume fraction of soft microdomains extracted from dynamic mechanical data is identified as a universal parameter that controls tensile behavior of the different blends studied.

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Section: Resultssupporting

confidence: 91%

Styrene−Butadiene Gradient Block Copolymers for Transparent Impact Polystyrene

et al. 2008

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“…Several authors have reported macrophase separation in binary blends containing block copolymers. Recently, Yamaoka16, 17 studied the morphology and toughness behavior of the blends of K‐Resin 05 and a statistical copolymer of poly(methyl methacrylate) and polystyrene (PMMA‐ co ‐PS) using compression‐molded samples and concluded that a macrophase separation between the blend components takes place. Previous works of Löwenhaupt and Hellmann18 on poly(styrene‐ block ‐methyl methacrylate) (PS‐ b ‐PMMA/PS) have also shown the macrophase separation of added PS if the molecular weight of the PS was larger than that of the corresponding block of PS‐ b ‐PMMA diblock copolymer.…”

Section: Resultsmentioning

confidence: 99%

Morphology and micromechanical deformation behavior of styrene–butadiene block copolymers. III. Binary blends of asymmetric star block copolymer with general‐purpose polystyrene

Adhikari

Michler

Goerlitz

et al. 2004

J of Applied Polymer Sci

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ABSTRACT:The correlation between morphology, mechanical properties, and micromechanical deformation behavior of the blends consisting of an asymmetric styrene/ butadiene star block copolymer (ST2-S74, total styrene volume content ⌽ PS ϭ 0.74) and general-purpose polystyrene (GPPS) was investigated using transmission electron microscopy and uniaxial tensile testing. Addition of 20 wt % of GPPS to the block copolymer resulted in a drastic reduction in strain at break, indicating the existence of critical PS lamella thickness D c . Above D c lamellar block copolymers displayed a transition from ductile to brittle behavior, substantiating the mechanism of thin layer yielding proposed for lamellar star block copolymers. The blends showed a variety of deformation structures ranging from classical crazelike zones to those with internal shearlike components.

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“…A rapidly cooled compression-molded sample stretched normal the lamellae showed clear evidence of a zigzag (chevron) morphology just below the fracture surface. More recently, similar investigations on SBS/poly(methyl methacrylate- block -styrene) blends have been carried out. , …”

Section: Tem Studies On Deformed Triblock Copolymer Morphologiesmentioning

confidence: 97%

Perpendicular Deformation of a Near-Single-Crystal Triblock Copolymer with a Cylindrical Morphology. 2. TEM

2000

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A poly(styrene-block-isoprene-block-styrene) (SIS) triblock copolymer with a polystyrene (PS) cylinder morphology was globally oriented via roll-casting. Transmission electron microscopy (TEM) was used to assess the quality of orientation. The roll-casting process produces films with near-single-crystal-like orientation. Large strain deformation was applied perpendicular to the cylinder axis and retained by irradiating the sample with high energy electrons. TEM of sections viewed parallel and perpendicular to the cylinder axis provided real space information on the deformed morphology. For views parallel to the cylinder axis, the initial hexagonal packing of the cylinders distorts into a faulted twinlike texture in which layers of cylinders are oriented at fixed angles with respect to the stretching direction (SD). These fault boundaries are separated by an average distance of about 0.1 μm at 180% deformation. Direct evidence for a chevron texture in which the cylinders kink and turn into the SD was observed at perpendicular incidence. Kink boundaries are separated by an average distance of about 5 μm at a strain of 180%. Optical transforms (OTs) of the TEM images as well as SAXS on deformed irradiated samples are used to directly connect the results to the dynamic SAXS described in a complementary paper. A 3-D model of the deformed morphology summarizes the real space data self-consistently and provides the basis for an interpretation of the dynamic SAXS data.

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Effects of morphology on mechanical properties of styrene-butadiene-styrene triblock copolymer/methyl methacrylate styrene copolymer blends

Cited by 10 publications

References 25 publications

Styrene−Butadiene Gradient Block Copolymers for Transparent Impact Polystyrene

Styrene−Butadiene Gradient Block Copolymers for Transparent Impact Polystyrene

Morphology and micromechanical deformation behavior of styrene–butadiene block copolymers. III. Binary blends of asymmetric star block copolymer with general‐purpose polystyrene

Perpendicular Deformation of a Near-Single-Crystal Triblock Copolymer with a Cylindrical Morphology. 2. TEM

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