Investigation of the micromechanical deformation behavior of styrene–butadiene star block copolymer/polystyrene blends with high‐voltage electron microscopy

Abstract

The deformation behavior of blends consisting of a styrene–butadiene star block copolymer and a polystyrene homopolymer was studied by high‐voltage electron microscopy with a tensile device. The mechanical properties and micromechanical deformation mechanisms in the star block copolymer/polystyrene blends were directly influenced by their morphology. Although the pure block copolymer deformed in a very unequal manner (because of a thin‐layer‐yielding mechanism) and revealed no local deformation zones, a transition to the formation of crazelike zones was observed in the blends. This transition in the deformation mechanisms was correlated to the abrupt change in the macroscopic strain at break of the injection‐molded specimens. At lower contents of added polystyrene, a craze‐stopping mechanism was observed, whereas the blends with higher polystyrene contents demonstrated crazing like that in pure polystyrene. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1157–1167, 2003

Three‐Phase Model of Two‐Component Blends Consisting of a Polystyrene–Polybutadiene Star Block Copolymer and a Polystyrene Homopolymer

“…The morphology of blends of an SB star block copolymer and PS, which ranges from microphase‐separated to macrophase‐separated structure depending on the molecular weight of the PS and the composition of the blends clearly affects the tensile mechanical properties . Material‐specific correlations between the morphology, the mechanical properties and the microdeformation behaviour have been also found for other SB star block copolymer/PS blends . One of our papers also deals with morphology–toughness correlations of blends composed of a SB star block copolymer (ST3) and PS homopolymer (ST3 has three short arms in average and one longer arm).…”

“…[6] Another study on four arm SB star block copolymer/ PS homopolymer (hPS) blends has revealed that the hardness increased with the increase in the PS-layer thickness. [7] The mechanical behaviour [8][9][10][11][12][13] and morphology [8][9][10][11][12][13][14][15][16][17] of blends of SB block copolymers and hPS have been repeatedly investigated in the last decade, mainly by Adhikari el al. [8][9][10][11][12][13][14] The morphology of blends of an SB star block copolymer and PS, which ranges from microphase-separated to macrophaseseparated structure depending on the molecular weight of the PS and the composition of the blends clearly affects the tensile mechanical properties.…”

“…[8] Material-specific correlations between the morphology, the mechanical properties and the microdeformation behaviour have been also found for other SB star block copolymer/PS blends. [10][11][12][13] One of our papers [18] also deals with morphologytoughness correlations of blends composed of a SB star block copolymer (ST3) and PS homopolymer (ST3 has three short arms in average and one longer arm). In this paper we presented a simple two-phase model to calculate the hard PS-rich domain thickness d PS with high accuracy assuming the domain thickness d PB of the soft phase as being constant.…”

Styrene/Butadiene Rubber Prepared by Anionic Bulk Polymerization in a Twin‐Screw Extruder

“…It is well known that during solution polymerization Bd reacts first in the system, and the product in the end is a tapered block polymer since the reactivity ratios of the monomers vary widely at room temperature . To avoid the block of St, the polarity regulator was introduced into the reaction system.…”

Deformation and alignment of lamellae in melt extension of blends of a styrene‐butadiene block copolymer with polystyrene

“…Consequently, blends of block copolymers and a homopolymer belong to a technologically highly important class of materials, and their mechanical and rheological properties are intensively studied. [7][8][9][10][11] Since processing of polymers is intimately related to the melt rheology in shear and elongation, a series of studies investigated the flow behavior and the deformation of pure block copolymers and related blend systems. [12][13][14][15][16][17][18][19][20] Besides the knowledge of the shear and extensional viscosity, additional elongational properties such as strain-hardening and melt stability are of interest for technological applications.…”