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

Macromolecular Symposia

2017

Summary Structure property correlations in a styrene‐butadiene star block copolymer melt mixed with varying amounts of multiwalled carbon nanotubes (MWCNTs) were evaluated. The MWCNTs are well dispersed within the matrix and do not significantly impact the star block copolymer morphology or the glass transition temperature. The electrical percolation threshold was found to be at ∼1 wt% of MWCNT concentration. A distinct increase in Young's modulus could be observed at a nanofiller content of 0.1 wt% while maintaining the elastomeric matrix property profile, an observation in tune with the rule‐of‐mixture prediction. Additionally the existence of double yielding was detected in these nanocomposites with a pronounced first yield point indicating a significant enhancement of stiffness in composites with low MWCNT content. Analysis of elastic moduli using Halpin‐Tsai and two‐phase Takayanagi model revealed a matrix‐controlled elastic response without any interfacial contribution due to MWCNT incorporation.

Section: Introductionmentioning

confidence: 99%

Influence of Carbon Nanotubes on the Morphology and Properties of Styrene‐Butadiene Based Block Copolymers

Staudinger

Macromolecular Symposia

2017

“…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).…”

Section: Introductionmentioning

confidence: 78%

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

Lach¹,

Macromolecular Symposia

Weidisch

et al. 2017

Summary Based on results of atomic force microscopy and dynamic mechanical analysis applied on binary blends of polystyrene (PS)–polybutadiene (PB) star block copolymers (ST3) having different compositions, a three‐phase morphology that comprises PB‐rich, PS/PB‐mixed and PS‐rich phase has been found. The pronounced enhancement of toughness in blends with 20–30 wt.‐% PS homopolymer compared to pure ST3 can be understood by improvement of the stress transfer between the microdomains through the additional hPS‐induced interfacial PS/PB‐mixed volume fraction and the co‐continuous morphology.

“…The thickening of PS lamellae above a critical thickness of 30 nm has been reported to undergo preferential local craze-like deformation zones. [18] In our study, however, the PS lamellae thickness (16-20 nm) is less than the critical thickness to cause local crazing. This inevitably led to a change in the macroscopic fracture behaviour with the corresponding change in the morphology from cylindrical to lamellar as reflected by the 35% increase in the magnitude of bw p .…”

Section: Load-displacement Diagramsmentioning

confidence: 84%

“…Similar observations in case of pure block copolymer with star architecture undergoing homogeneous deformation of the PS and PB lamella and thereby causing a reduction in lamellar thickness without any signs of locally confined deformation zones have been reported. [18] This has been attributed in the literature to the microscopic plastic flow of PS lamellae as reported by Hashimoto et al [19] in case of SBS block copolymer systems or alternatively termed as 'thin layer yielding' in case of block copolymer blends. [20] On the other hand, in case of blends with 70 wt.-% LN3 content the dimensions of PS layer (lamellae) thickness qualitatively has been observed to increase which, however, has to be quantitatively ascertained in future.…”

Section: Load-displacement Diagramsmentioning

confidence: 96%

Strain Field Analysis and Kinetics of Crack Propagation of Binary Triblock Copolymer Blends

Macromol. Rapid Commun.

Staudinger

Weidisch

et al. 2006

Summary: The crack toughness behaviour of binary styrene‐butadiene (SB) triblock copolymer blends of a thermoplastic block copolymer (LN3) and a thermoplastic elastomer (LN4) with different molecular architecture was studied using essential work of fracture (EWF) concept and was correlated to the morphological features from transmission electron microscopy (TEM). An increase in the crack toughness behaviour between 60 and 80 wt.‐% LN3 has been observed and is attributed to a change from cylindrical to lamellar morphology. The time‐resolved crack propagation studies have offered new dimensions to understand the kinetic aspects of fracture behaviour while the strain field analysis has explained the time‐dependent deformation behaviour to characterise the time dependence of the strain energy dissipation modes.Load‐displacement diagrams of non essential work of fracture values of LN3/LN4 blends.magnified imageLoad‐displacement diagrams of non essential work of fracture values of LN3/LN4 blends.