Toward an Improved Description of Constraint Release and Contour Length Fluctuations in Tube Models for Entangled Polymer Melts Guided by Atomistic Simulations

Stephanou, Pavlos S.; Baig, Chunggi; Mavrantzas, Vlasis G.

doi:10.1002/mats.201100052

Cited by 23 publications

(20 citation statements)

References 63 publications

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“…Doi suggested [12] that the effective length, 1−ΔL/L, decreases with the chain length as 1−X/Z and X being a constant larger than 1.47. Stephanou predicted [67] the value of X from the primitive path analysis to be close to 1/3.…”

Section: Comprehension Of Clf In the Tube Modelsmentioning

confidence: 99%

Comparative Analysis of Different Tube Models for Linear Rheology of Monodisperse Linear Entangled Polymers

2019

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The aim of the present paper is to analyse the differences between tube-based models which are widely used for predicting the linear viscoelasticity of monodisperse linear polymers, in comparison to a large set of experimental data. The following models are examined: Milner–McLeish, Likhtman–McLeish, the Hierarchical model proposed by the group of Larson, the BoB model of Das and Read, and the TMA model proposed by the group of van Ruymbeke. This comparison allows us to highlight and discuss important questions related to the relaxation of entangled polymers, such as the importance of the contour-length fluctuations (CLF) process and how it affects the reptation mechanism, or the contribution of the constraint release (CR) process on the motion of the chains. In particular, it allows us to point out important approximations, inherent in some models, which result in an overestimation of the effect of CLF on the reptation time. On the contrary, by validating the TMA model against experimental data, we show that this effect is underestimated in TMA. Therefore, in order to obtain accurate predictions, a novel modification to the TMA model is proposed. Our current work is a continuation of earlier research (Shchetnikava et al., 2014), where a similar analysis is performed on well-defined star polymers.

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Section: Comprehension Of Clf In the Tube Modelsmentioning

confidence: 99%

Comparative Analysis of Different Tube Models for Linear Rheology of Monodisperse Linear Entangled Polymers

2019

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“…Based on the Z1 code [281], Stephanou et al [74,89,[291][292][293] developed a dynamic mapping method to quantify polymer chain reptation in entangled polymer melts. As shown in Figure 17a, a virtual tube with diameter, a pp , is constructed around a real polymer chain and its PP, where the tube diameter, a pp , can be determined independently through either the calculation of the MSD for the innermost monomers of the polymer chains or the time displacement of the primitive chain segment orthogonal to the initial PP.…”

Section: Dynamic Mapping Onto Tube Modelmentioning

confidence: 99%

“…More importantly, the CR effect is found to be the dominant relaxation mechanism in the mixtures of longer and shorter cis-1,4-PB polymers, since the CLF effect appears to be independent of the compositional differences [74]. Later on, such a method was applied to improve the theoretical descriptions on the CLF and CR effects in the tube model [293]. Figure 19.…”

Section: Dynamic Mapping Onto Tube Modelmentioning

confidence: 99%

Challenges in Multiscale Modeling of Polymer Dynamics

et al. 2013

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The mechanical and physical properties of polymeric materials originate from the interplay of phenomena at different spatial and temporal scales. As such, it is necessary to adopt multiscale techniques when modeling polymeric materials in order to account for all important mechanisms. Over the past two decades, a number of different multiscale computational techniques have been developed that can be divided into three categories: (i) coarse-graining methods for generic polymers; (ii) systematic coarse-graining methods and (iii) multiple-scale-bridging methods. In this work, we discuss and compare eleven different multiscale computational techniques falling under these categories and assess them critically according to their ability to provide a rigorous link between polymer chemistry and rheological material properties. For each technique, the fundamental ideas and equations are introduced, and the most important results or predictions are shown and discussed. On the one hand, this review provides a comprehensive tutorial on multiscale computational techniques, which will be of interest to readers newly entering this field; on the other, it presents a critical discussion of the future opportunities and key challenges in the multiscale geometric mapping matrix between all-atomistic and coarse-grained models N number of monomers per chain N e entanglement length, which is the number of monomers between two entanglements n v number of polymer chains per unit volume n ij (n 0 (r ij )) entanglement number (at equilibrium) between particle pairs i and j p r , P R configurational probability distributions in all-atomistic and coarse-grained models, respectively R ee end-to-end distance of polymer chain R G radius of gyration of polymer chain s segment index/contour length variable along primitive chain S(q) single chain coherent dynamic scattering function Z number of entanglements per chain, defined as Z = N/N e α exponent in standard Mittag-Leffler function σ

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“…Determination of the characteristic time scale τ K for sliding of a Kuhn step through an entanglement, which is the single adjustable parameter for the dynamics of the MSM [38][39][40][41][42][43][44]59], is beyond the scope of the present paper. A few works have been devoted to the determination of dynamic properties of reptation models, such as the tube segment survival probability [89][90][91]. We argue that the MSM is a more suitable target to map dynamic multi-chain properties onto than the tube model, again because the MSM includes more of the fluctuations present in multi-chain systems.…”

Section: Appendix C Relation To Recent Workmentioning

confidence: 95%

Primitive-path statistics of entangled polymers: mapping multi-chain simulations onto single-chain mean-field models

et al. 2014

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We present a method to map the full equilibrium distribution of the primitivepath (PP) length, obtained from multi-chain simulations of polymer melts, onto a single-chain mean-field 'target' model. Most previous works used the Doi-Edwards tube model as a target. However, the average number of monomers per PP segment, obtained from multi-chain PP networks, has consistently shown a discrepancy of a factor of two with respect to tube-model estimates. Part of the problem is that the tube model neglects fluctuations in the lengths of PP segments, the number of entanglements per chain and the distribution of monomers among PP segments, while all these fluctuations are observed in multi-chain simulations. Here we use a recently proposed slip-link model, which 7 Current address: Dow

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Toward an Improved Description of Constraint Release and Contour Length Fluctuations in Tube Models for Entangled Polymer Melts Guided by Atomistic Simulations

Cited by 23 publications

References 63 publications

Comparative Analysis of Different Tube Models for Linear Rheology of Monodisperse Linear Entangled Polymers

Comparative Analysis of Different Tube Models for Linear Rheology of Monodisperse Linear Entangled Polymers

Challenges in Multiscale Modeling of Polymer Dynamics

Primitive-path statistics of entangled polymers: mapping multi-chain simulations onto single-chain mean-field models

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