SAXS observation of RCM1 under cyclical shear

Cooney, D.; DeRocher, Jonathan P.; Moggridge, Geoff D.; Squires, Adam M.

doi:10.1007/s10853-007-1947-5

Cited by 4 publications

(6 citation statements)

References 22 publications

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“…The values of orientation function for RCM1 processed in cycle '5-5-18' (Fig. 5a), at high wall shear rate (1125 s À1 ) are in agreement with the previous work, 31 where individual frames were collected for 5 s. Our data represent higher time resolution, 1 s frames. The data reveal a trend of decreasing P 2 values during flow and increasing orientation in the pause period.…”

Section: X-ray Experimentssupporting

confidence: 91%

“…To investigate the dynamics of microstructure changes during processing we applied a time resolved technique described by Cooney et al 31 The method is based on collection of many short X-ray exposures over many repetitions of the same deformation cycle. The overall X-ray image was a sum of frames taken in the same cycle step.…”

Section: Methodsmentioning

confidence: 99%

“…The optical train consisted of: polariser lens at 0 , quarter-wave plate at 45 , sample between quartz windows, quarter-wave plate at 135 and analyser lens at 90 . To investigate the dynamics of microstructure changes during processing we applied a time resolved technique described by Cooney et al 31 The method is based on collection of many short X-ray exposures over many repetitions of the same deformation cycle. The overall X-ray image was a sum of frames taken in the same cycle step.…”

mentioning

confidence: 99%

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Dynamics of shear-induced orientation transitions in block copolymers

et al. 2010

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This research investigates the dynamics of mechanical and structural transformations of styrenebutadiene-styrene block copolymer, known as RCM1, which has cylindrical mesophase morphology. The polymer was processed using a Multipass Rheometer (MPR) with simultaneous X-ray observation. The method allowed investigation of the dynamics with 1 second time resolution. Samples were processed at 160 C and an apparent wall shear rate in the range $1.4 to 1125 s À1 . Microstructural alignment was quantified using a second order X-ray orientation function. The polymer showed self-organization in the melt, aligning along the capillary walls. Shear flow disrupted the organization, which then rebuilt during the post-shearing pause, as the residual pressure relaxed across the capillary. The dynamics of structure ordering and disordering was a function of shear rate. The transition was faster for high shear rate cycles.

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Section: X-ray Experimentssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Dynamics of shear-induced orientation transitions in block copolymers

et al. 2010

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“…The assumption of structural and dynamic symmetry, however, is often invoked in theory and simulation.There are already several experimental investigations on the orientation kinetics of DBCPs in mechanical fields, [1,[28][29][30][31][32] but the polymer systems used in these experiments did not have similar dynamics in both polymer blocks, making a compar ison to computer simulations untractable, because the simula tion times of the orientation process scales linearly with the dif ference in polymer dynamics and thus cannot be conducted in a reasonable time frame.Recent rheological studies could not answer these questions on the local reorientation processes for dynamically symmetric copolymers on the microscopic length scale. [33][34][35][36][37][38] To under stand the process on this length scale, experiments should be supported by computer simulations and vice versa. To cover the multiple time and length scales involved in those processes,…”

mentioning

confidence: 99%

“…Recent rheological studies could not answer these questions on the local reorientation processes for dynamically symmetric copolymers on the microscopic length scale. [33][34][35][36][37][38] To under stand the process on this length scale, experiments should be supported by computer simulations and vice versa. To cover the multiple time and length scales involved in those processes,…”

mentioning

confidence: 99%

Diblock Copolymers with Similar Glass Transition Temperatures in Both Blocks for Comparing Shear Orientation Processes with DPD Computer Simulations

Heck

Schneider

Müller

et al. 2018

Macro Chemistry & Physics

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The purpose of this study is the development of phase‐separating diblock copolymer model systems suitable for the comparison between the orientation process under shear and computer simulations of the same process. To do so, the polymer systems have to fulfill certain requirements like similar dynamics of both polymer blocks, which are associated with comparable glass transition temperatures. The development of suitable diblock copolymer systems such as poly(ethyl methacrylate)‐b‐poly(2‐vinylpyridine) or the tuning of already established polymer systems like polystyrene‐b‐poly(2‐vinylpyridine) via copolymerization with 4‐vinylpyridine is essential. Anionic polymerization is used for the sample synthesis to achieve this goal with the lowest possible polydispersity. Soft, coarse‐grained models are used to study the block dynamics in computer simulations. Within the dissipative particle dynamics methods the remaining differences in the block mobility are addressed. The experimentally determined zero‐shear viscosity η0 is used to match the simulation results to the synthesized polymer melts.

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In Situ SAXS Studies of Structural Relaxation of an Ordered Block Copolymer Melt Following Cessation of Uniaxial Extensional Flow

McCready

Burghardt

2014

Macromolecules

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A hexagonally ordered styrene–ethylene-co-butylene–styrene triblock copolymer melt is studied during and immediately following uniaxial extensional flow using small-angle X-ray scattering. Strips of polymer melt are stretched between counter-rotating drums inside an oven designed for in situ synchrotron studies. Previous study of this sample demonstrated deformation and reorientation of PS microdomains and identified a critical Hencky strain ∼0.2 at which the structure is dramatically disrupted. To further probe microstructural dynamics, we study relaxation behavior of structure and stress in samples stretched in the melt to various Hencky strains. Upon cessation of stretching below the critical strain, structural relaxation is strongly retarded; stretching to higher strain leads to more rapid relaxation. At all strains, microdomain orientation relaxation following flow is slower than relaxation of flow-induced deformation and mechanical stress. The extension rate dependence of the sample’s response is also explored; higher rates result in faster relaxation of both stress and structure.

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SAXS observation of RCM1 under cyclical shear

Cited by 4 publications

References 22 publications

Dynamics of shear-induced orientation transitions in block copolymers

Dynamics of shear-induced orientation transitions in block copolymers

Diblock Copolymers with Similar Glass Transition Temperatures in Both Blocks for Comparing Shear Orientation Processes with DPD Computer Simulations

In Situ SAXS Studies of Structural Relaxation of an Ordered Block Copolymer Melt Following Cessation of Uniaxial Extensional Flow

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