Mechanistic model for deformation of polymer nanocomposite melts under large amplitude shear

Şenses, Erkan; Akcora, Pinar

doi:10.1002/polb.23247

Cited by 13 publications

(11 citation statements)

References 29 publications

(39 reference statements)

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“…27 The self-stiffening behavior observed aer multiple deformation stages suggests that stretching and deformation of polymer chains were different in the PMMA composite, and entanglement of chains near particle surfaces can be tuned by oscillatory shear deformation. These recent reported results [26][27][28] on "bare" particle lled polymers guide us to investigate interface effects between graed and matrix chains in LAOS since it is expected that shear ow elds can alter the interpenetration between gras and free chains.…”

Section: Linear Rheology Measurementsmentioning

confidence: 78%

“…In our previous work on the non-attractive PS-SiO 2 composite system, we have reported that at large strains the polymer deforms similar to polymer networks due to possible stretching of chains between particle clusters and breaking of interconnected particles manifests yielding at intermediate strains. 26 In contrast, in the attractive PMMA-SiO 2 composite where particles are well-dispersed, stress increases monotonically with strain and presents no yielding. 27 The self-stiffening behavior observed aer multiple deformation stages suggests that stretching and deformation of polymer chains were different in the PMMA composite, and entanglement of chains near particle surfaces can be tuned by oscillatory shear deformation.…”

Section: Linear Rheology Measurementsmentioning

confidence: 99%

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Modulating interfacial attraction of polymer-grafted nanoparticles in melts under shear

2014

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The mechanical properties of polymer nanocomposites are significantly affected by spatial ordering of nanoparticles (NPs) which can be modified under shear flow fields. Polymer-grafted iron oxide NPs form strings, well-dispersed, and percolated anisotropic nanostructures depending on grafting density, and herein their mechanical properties under large oscillatory shear flows are reported. We show that flow-induced alignment of NPs is achieved with string-like structures at low particle loadings (5 wt%). Further, entropic surface tension between grafted and free chains decreases by facilitating the penetration of long matrix chains into the grafts with oscillatory shear flow. Consequently, the degree of entanglements at large strain amplitudes is enhanced which is reflected in elastic properties. These results indicate that the matrix polymer plays an effective role in the reinforcement of polymer-grafted NPs under large shear flow fields.

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Section: Linear Rheology Measurementsmentioning

confidence: 78%

Section: Linear Rheology Measurementsmentioning

confidence: 99%

Modulating interfacial attraction of polymer-grafted nanoparticles in melts under shear

2014

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“…Rheologically, network and dispersion properties have been typically assigned to the slope of the storage modulus G ′ in the terminal regime at percolation for very low angular frequencies. Generally, it is considered that the stress response at small strains is the result of percolated particle network, whereas the large strain behavior is determined by the polymer chain dynamics (Senses and Akcora 2013).…”

Section: Polymer Nanocomposites and Percolationmentioning

confidence: 99%

Nonlinear “oddities” at the percolation of 3D hierarchical graphene polymer nanocomposites

2020

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The nonlinear rheology of a novel 3D hierarchical graphene polymer nanocomposites was investigated in this study. Based on an isotactic polypropylene, the nanocomposites were prepared using simple melt mixing, which is an industrially relevant and scalable technique. The novel nanocomposites stand out as having an electrical percolation threshold (≈0.94 wt%) comparable to solution mixing graphene-based polymer nanocomposites. Their nonlinear flow behavior was investigated in oscillatory shear via Fourier-transform (FT) rheology and Chebyshev polynomial decomposition. It was shown that in addition to an increase in the magnitude of nonlinearities with filler concentration, the electrical percolation threshold corresponds to a unique nonlinear rheological signature. Thus, in dynamic strain sweep tests, the nonlinearities are dependent on the applied angular frequency, potentially detecting the emergence of a weakly connected network that is being disrupted by the flow. This is valid for both the third relative higher harmonic from Fourier-transform rheology, I 3/1 , as well as the third relative viscous, v 3/1 , Chebyshev coefficient. The angular frequency dependency comprised non-quadratic scaling in I 3/1 with the applied strain amplitude and a sign change in v 3/1. The development of the nonlinear signatures was monitored up to concentrations in the conductor region to reveal the influence of a more robust percolated network.

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“…Holt et al also simulated particle–polymer interactions of varying strengths and molecular weights and found that for stronger chain attachment through covalent bonding, particle‐attached chains are stretched near the particle surface, while still entangled with the bulk matrix far away from the surface. Senses and Akcora derived a mechanistic model to predict the elastic stress buildup in polystyrene/silica nanocomposites under LAOS flows and found that the model matches well with experiments when chains near the filler surface are stretched. These results imply that the degree of stretch varies along the attached chain segments during flow.…”

Section: Resultsmentioning

confidence: 86%

Dynamics of entangled polymer chains with nanoparticle attachment under large amplitude oscillatory shear

Hershey

Jayaraman

2018

J Polym Sci B Polym Phys

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This paper presents a nonlinear viscoelastic model for polymer nanocomposites and the computed model response to large amplitude oscillatory shear flow. The model predicts the stress in a mixture of entangled polymer chains, with different convective constraint release (CCR) rates for free chains and nanoparticle-attached chains, through an averaging scheme which is consistent with double reptation in the Marrucci-Ianniruberto constitutive equation. The nonlinear response of the mixture is evaluated both numerically in terms of Q and by an asymptotic analysis in terms of four frequency dependent parameters of medium amplitude oscillatory shear (MAOS) as well as the intrinsic nonlinearity parameter Q 0 . In the case of free polymer chains alone, the MAOS signatures are comparable to those of the Giesekus model with the notable difference of a minimum in the elastic parameter [e 1 ] at De >1. The viscous nonlinear parameters of the mixture model depart significantly from those of the free chains, especially in mixtures where the CCR parameter for attached chains is larger than that for the free chains:[v 1 ] has a prominent minimum and [v 3 ] has a prominent maximum near De = 2/c, the low frequency plateau region, along with a higher Q 0 compared to the matrix at all Deborah numbers.

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Mechanistic model for deformation of polymer nanocomposite melts under large amplitude shear

Cited by 13 publications

References 29 publications

Modulating interfacial attraction of polymer-grafted nanoparticles in melts under shear

Modulating interfacial attraction of polymer-grafted nanoparticles in melts under shear

Nonlinear “oddities” at the percolation of 3D hierarchical graphene polymer nanocomposites

Dynamics of entangled polymer chains with nanoparticle attachment under large amplitude oscillatory shear

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