Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses

Lentzakis, Helen; Costanzo, Salvatore; Vlassopoulos, Dimitris; Colby, Ralph H.; Read, Daniel J.; Lee, Hyojoon; Chang, Taihyun; Ruymbeke, Evelyne Van

doi:10.1021/acs.macromol.9b00251

Cited by 23 publications

(44 citation statements)

References 77 publications

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“…Most of these models predict chain relaxation in the so-called terminal regime of the viscoelastic behavior, where, e.g., within a DTD mechanism, the tube would reach its final dilated value. Accordingly, the experimental studies are usually based on macroscopic rheological or dielectric techniques (see, e.g., [9][10][11][12][13]). A direct experimental microscopic observation of the time dependence of the CR or DTD mechanisms remains elusive [14,15].…”

mentioning

confidence: 99%

Direct Observation of Dynamic Tube Dilation in Entangled Polymer Blends: A Combination of Neutron Scattering and Dielectric Techniques

et al. 2019

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confidence: 99%

Direct Observation of Dynamic Tube Dilation in Entangled Polymer Blends: A Combination of Neutron Scattering and Dielectric Techniques

et al. 2019

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“…for the case of star polymers diluted in a linear matrix. While eqs and yield very similar results if the linear matrix is not too entangled ( Z linear < 10), they largely differ if longer matrices are used . However, these equations were not tested in this regime, which is difficult to reach experimentally.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we investigated the viscoelastic properties of a H-polymer diluted in linear matrices of different molar masses and concentration . When diluted in an oligomeric matrix at concentration low enough to avoid self-entanglements, it was found that the terminal relaxation of the H backbone was well described by a Rouse process, but with a delay θ H due to the extra friction coming from the branches attached to the backbone.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we build-up on our earlier work and investigate the relaxation dynamics of a (more complex) comb polymer ,,− diluted in different linear matrices (same as in ref ) encompassing the three situations, as shown in Figure . The following specific challenges are addressed: Because the same linear polymers are used as in ref , we would like to examine whether the same delay factor θ matrix can be used to determine the CRR of the comb’s branches.…”

Section: Introductionmentioning

confidence: 99%

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Linear Viscoelastic Response of Comb/Linear Polymer Blends: A Three-Step Relaxation Process

2021

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This study addresses the linear viscoelasticity of blends involving monodisperse comb and linear polymers, the latter being the matrix of varying molar mass. This is dynamically a three-component system, comprising linear chains, branches (which are short enough to undergo essentially Rouse relaxation), and backbones. We examine systematically the relaxation of the same comb diluted in the linear matrix as a function of the molar mass of the linear chain for all possible situations (when the latter is oligomer or polymer relaxing faster or slower than the branches) as well as the case of backbone self-entanglements. We develop a simple tube model for the contributions of the three components to comb relaxation by accounting for the dynamic dilution and two delay factors, one for the matrix and another for the comb. The former represents the frictional contribution of the linear polymers to the constraint release Rouse process of the branches and backbone, and the latter represents the relevant effect of the branches on the backbone motion. The model provides an excellent quantitative description of the experimental data. The resulting retardation factors controlling the relaxation process of the combs as a function of the linear polymer’s molar mass complement and extend our earlier investigations with blends involving H-polymers in linear matrices, pointing toward a universal description of the dynamic response of architecturally complex polymers in linear matrices based on constraint release mechanisms. This finding enhances our ability to tailor the dynamics of topological homopolymer blends as per our wish. The remaining challenges associated with the possible universality of the delay factor of combs and the coupling of branch and backbone motion are discussed.

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“…An active area of research for polymer solutions and melts containing both branched and linear polymers is to understand how the presence of a linear chain matrix influences the relaxation of branched chains. In the linear viscoelastic regime, significant progress has been made and different theoretical models describe accurately the effects of adding branched polymers into a linear matrix [7][8][9][10]. Actually, a recent study by R. Hall et al has shown that when the linear polymer has a relaxation time longer than the star component, the terminal relaxation time dependence has non-monotonic dependence on the blend composition, and this result is obtained both theoretically and experimentally [11].…”

Section: Introduction and Theoretical Backgroundmentioning

confidence: 99%

Microstructural characterization of a star-linear polymer blend under shear flow by using rheo-SANS

Andriano

Ruocco

Peterson

et al. 2020

Journal of Rheology

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We present an investigation into the dynamic relaxation mechanisms of a polybutadiene blend composed of a four-arm star (10% by wt) and a linear polymer matrix in the presence of an applied shear flow. Our focus was the response of the star polymer, which cannot be unambiguously assessed via linear viscoelastic measurements since the signature of the star polymer can barely be detected due to the dominant contribution of the linear matrix. By utilizing small-angle neutron scattering (SANS) coupled with a Couette shear device and a deuterated matrix polymer, we investigated the dynamics of the minority star component of the blend. Our results confirm that the stars deform anisotropically with increasing shear rate. We have compared the SANS data with predictions from the well-established scattering adaptation of the state-of-the-art tube model for entangled linear polymer melts undergoing shear, i.e. Graham, Likhtman, Milner and McLeish (GLaMM) approach, appropriately modified following earlier studies in order to apply to the star. This modified model, GLaMM-R, includes the physics necessary to understand stress relaxation in both the linear and nonlinear flow regimes, i.e. contour length fluctuations (CLF), constraint release (CR), convective constraint release (CCR) and chain retraction. The full scattering signal is due to the minority star component and, although the contribution of the linear chains is hidden from the neutron scattering, they still influence the star polymer molecular dynamics, with the applied shear rate ranging from approximately 8 to 24s -1 , below the inverse relaxation time of the linear component. This study provides another confirmation that the combination of rheology and neutron scattering is an indispensable tool for investigating the nonlinear dynamics of complex polymeric systems.

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Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses

Cited by 23 publications

References 77 publications

Direct Observation of Dynamic Tube Dilation in Entangled Polymer Blends: A Combination of Neutron Scattering and Dielectric Techniques

Direct Observation of Dynamic Tube Dilation in Entangled Polymer Blends: A Combination of Neutron Scattering and Dielectric Techniques

Linear Viscoelastic Response of Comb/Linear Polymer Blends: A Three-Step Relaxation Process

Microstructural characterization of a star-linear polymer blend under shear flow by using rheo-SANS

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