Kashefi's &lt;i&gt;Anvar-e Sohayli&lt;/i&gt;

Ruymbeke, Christine van

doi:10.1163/9789004314757

Cited by 7 publications

(8 citation statements)

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“…A broader molar mass distribution would extend the shear thinning behavior [20]. It was shown that based on the storage modulus G 0 and loss modulus G 00 , prediction of the molar mass distribution can be achieved [21,22]. The analysis of the loss angle leads to information on the content of branched [23][24][25] and gel-like moieties [25][26][27].…”

mentioning

confidence: 99%

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Kruse

Wang

Shah

et al. 2018

Polymer Engineering & Sci

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Three grades of poly(ethylene terephthalate) (PET) produced by different synthesis routes and with different molar masses were reactively extruded with two tetra‐functional chain extenders, i.e., pyromellitic dianhydride (PMDA) and tetraglycidyl diamino diphenyl methane (TGDDM). The preferred reactivity of the coupling agents led to different long‐chain branched (LCB) structures, which can be related to different hydroxyl and carboxyl end group concentrations of the PET grades investigated. The complex viscosity and the transient elongational viscosity increased by up to two decades. Both the activation energy of flow and the loss angle indicate long‐chain branching. A more quantitative assessment of the extent of strain hardening was achieved by application of the molecular stress function (MSF) model. The two material parameters of the model revealed different behaviors depending on the chain extender used. The initial molar mass of PET and the concentration of end groups, i.e., hydroxyl and carboxyl, determine the structure of the polymer molecules. PMDA proved to be an excellent coupling agent for industrial processing which induces reproducibly either a star‐like, comb‐like, or randomly branched structure depending on the concentration of coupling agent added and the hydroxyl concentration of the PET employed. TGDDM led to a hyperbranched structure. POLYM. ENG. SCI., 59:396–410, 2019. © 2018 Society of Plastics Engineers

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mentioning

confidence: 99%

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Kruse

Wang

Shah

et al. 2018

Polymer Engineering & Sci

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“…[ 10 ] However, the use of the above correlation remains limited as it cannot accurately describe broad MWD polyethylene while zero shear viscosity can be very diffi cult to measure for samples with long terminal relaxation times. [ 11,12 ] The shear rate, γ , viscosity dependency can be further described based on zero shear viscosity value by the generalized Cross viscosity correlation…”

Section: Rheology In Polymer Industrymentioning

confidence: 99%

“…Following the work of van Ruymbeke et al and basic rheology theory found in literature, [ 5,11,[19][20][21] a method and a software application is developed for predicting linear viscoelastic properties of entangled linear polymer melts based on MWD measurements. In what follows a short description of the model employed is presented.…”

Section: Linking Molecular Properties To the Flow Curvementioning

confidence: 99%

Connecting Linear Polymers Molecular Structure to Viscoelastic Properties and Melt Flow Index

Touloupidis

Wurnitsch

Albunia

et al. 2016

Macro Theory & Simulations

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A modeling pathway and software tool for linking entangled linear polymer molecular properties to linear viscoelasticity and melt index (MI) values is presented. A reptation model links molecular properties to the flow curve, and then, an ANSYS Polyflow model calculates MI values based on the flow curve predicted. The method is thoroughly tested and validated for uni‐ and bimodal, low‐ and high‐density polyethylene grades. An overall accuracy level in the range of 90% on average is exhibited, considering both model prediction steps: (i) molecular weight distribution to flow curve and (ii) flow curve to MI.

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“…17,18 A distinct physical framework for intra-and, most importantly, intermolecular assembly driven by competing interactions is offered within the broad field of associating polymers. [19][20][21] Whereas polymer chains are held together via irreversible, covalent bonds, associating polymers contain units that are capable of forming reversible, physical bonds with similar units of other chains. These include van der Waals interactions, p-p stacking, hydrogen bonding and metal-ligand coordination, 21,22 and they cover at least two orders of magnitude in terms of binding energy, ranging from one to several hundred kJ mol À1 .…”

Section: Introductionmentioning

confidence: 99%

“…[19][20][21] Whereas polymer chains are held together via irreversible, covalent bonds, associating polymers contain units that are capable of forming reversible, physical bonds with similar units of other chains. These include van der Waals interactions, p-p stacking, hydrogen bonding and metal-ligand coordination, 21,22 and they cover at least two orders of magnitude in terms of binding energy, ranging from one to several hundred kJ mol À1 . The reversibility of the bonds leads, at high concentrations, to the formation of reconfigurable, supramolecular networks, 19,20 a feature common with the systems that are the subject of the current manuscript.…”

Section: Introductionmentioning

confidence: 99%

Self-organization of gel networks formed by block copolymer stars

2019

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The equilibrium properties of block copolymer star networks (BCS) are studied via computer simulations.We employ both molecular dynamics and multiparticle collisional dynamics simulations to investigate the self-organization of BCS with f = 9 functionalized arms close to their overlap concentrations under conditions of different fractions of functionalization and varying attraction strength. We find three distinct macroscopic self-organized states depending on fraction of attractive end-monomers and the strength of the attraction. At weak attractions, ergodic, diffusive liquids result, with short-lived bonds between the stars. As the attraction strength grows, the whole system forms a percolating cluster, while at the same time the individual molecules are diffusive. Finally, arrested gels emerge when the attractions become strong. The conformation of the BCS in these solutions is found to be strongly affected by the concentration, with the stars assuming typically spherical, open configurations in seeking to maximize inter-star associations as opposed to the inter-star collapse that results at infinite dilution, giving rise to strongly aspherical shapes and reduced sizes.

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Kashefi's <i>Anvar-e Sohayli</i>

Cited by 7 publications

References 0 publications

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Connecting Linear Polymers Molecular Structure to Viscoelastic Properties and Melt Flow Index

Self-organization of gel networks formed by block copolymer stars

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