Relaxation Dynamics of Entangled and Unentangled Multiarm Polymer Solutions:  Experiment

Juliani,; Archer, Lynden A.

doi:10.1021/ma0205010

Cited by 13 publications

(3 citation statements)

References 17 publications

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“…Conversely, the high-frequency G' and G'' of SC dispersions increase much more slowly with concentration. For entangled polymer solutions in good solvent, the usual variation of the "plateau" modulus G'p is a power law C n with an exponent n » 2-2.3, 59,60 that is in agreement with the theoretical predictions of de Gennes 61,62 (n = 9/4). For SC dispersions at C < 150 g/L, the high-frequency value of G' follows a much steeper power law where G' ~ C 11 (Fig.…”

Section: (B))supporting

confidence: 83%

Rheology and phase behavior of dense casein micelle dispersions

Bouchoux¹,

Debbou²,

Gésan-Guiziou³

et al. 2009

The Journal of Chemical Physics

100

117

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Casein micelle dispersions have been concentrated through osmotic stress and examined through rheological experiments. In conditions where the casein micelles are separated from each other, i.e., below random-close packing, the dispersions have exactly the flow and dynamic properties of the polydisperse hard-sphere fluid, demonstrating that the micelles interact only through excluded volume effects in this regime. These interactions cause the viscosity and the elastic modulus to increase by three orders of magnitude approaching the concentration of random-close packing estimated at C(max) approximately 178 g/l. Above C(max), the dispersions progressively turn into "gels" (i.e., soft solids) as C increases, with elastic moduli G(') that are nearly frequency independent. In this second regime, the micelles deform and/or deswell as C increases, and the resistance to deformation results from the formation of bonds between micelles combined with the intrinsic mechanical resistance of the micelles. The variation in G(') with C is then very similar to that observed with concentrated emulsions where the resistance to deformation originates from a set of membranes that separate the droplets. As in the case of emulsions, the G(') values at high frequency are also nearly identical to the osmotic pressures required to compress the casein dispersions. The rheology of sodium caseinate dispersions in which the caseins are not structured into micelles is also reported. Such dispersions have the behavior of associative polymer solutions at all the concentrations investigated, further confirming the importance of structure in determining the rheological properties of casein micelle systems.

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Section: (B))supporting

confidence: 83%

Rheology and phase behavior of dense casein micelle dispersions

Bouchoux¹,

Debbou²,

Gésan-Guiziou³

et al. 2009

The Journal of Chemical Physics

100

117

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“…This very much resembles the behavior of Rouse‐chains, i.e., polymer chains which do not have entanglements. [ 17–23 ]…”

Section: Resultsmentioning

confidence: 99%

Effect of n‐Alkyl Side Chain Length on the Thermal and Rheological Properties of PolyN‐(3‐(alkylamino)‐N‐(3‐(isopropylamino)‐3‐oxopropyl)acrylamide) Homopolymers

Kumari

Vishwakarma

Mitra

et al. 2021

Macro Chemistry & Physics

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Four new N‐isopropylacrylamide‐ and N‐n‐alkyl amine‐based acrylamide monomers, N‐(3‐(alkylamino)‐N‐(3‐(isopropylamino)‐3‐oxopropyl) acrylamide (Mn) (n = 4, 8, 10, 12) are successfully synthesized and polymerized via reversible addition‐fragmentation chain‐transfer polymerization (polyMn, n = 4, 8, 10, and 12), which are characterized by gel permeation chromatography, 1H NMR, Fourier transform infra red spectroscopy, thermo‐gravimetry‐differential thermal analysis, differential scanning calorimetry (DSC), and rheology. All polymers are thermally stable and undergo a two‐step degradation process at ≈280 and ≈375 °C. Glass transition temperature (Tg)s of these polymers decrease gradually from 99.6 to 52.5 °C with increasing n‐alkyl side chain length. The rheology of these polymers in melt state agrees to a typical Rouse‐melt behavior and allows for confirming the Tg determined from DSC. Benzyl alcohol solution rheology proves a weak structural build‐up, in particular for polyM12. Comparison of the quantum chemical calculations of polyMns with n = 4–8 reveals increase in backbone helicity with increasing n‐alkyl side chain length.

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“…The properties of the branched polymer in equilibrium and nonequilibrium conditions have been investigated by theoretical analysis [ 25 , 26 , 27 , 28 , 29 ], experiments [ 24 , 26 , 27 , 30 , 31 , 32 , 33 ] and simulations [ 9 , 34 , 35 , 36 , 37 , 38 , 39 ]. The influence of long-chain branching on the rheological properties of conventional polyolefins, such as polyethylene (PE) [ 40 , 41 , 42 , 43 , 44 ] and polypropylene (PP), has been investigated [ 45 , 46 , 47 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamical and Structural Properties of Comb Long-Chain Branched Polymer in Shear Flow

Wang

Wen

Zhang

et al. 2022

IJMS

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Using hybrid multi-particle collision dynamics (MPCD) and a molecular dynamics (MD) method, we investigate the effect of arms and shear flow on dynamical and structural properties of the comb long-chain branched (LCB) polymer with dense arms. Firstly, we analyze dynamical properties of the LCB polymer by tracking the temporal changes on the end-to-end distance of both backbones and arms as well as the orientations of the backbone in the flow-gradient plane. Simultaneously, the rotation and tumbling behaviors with stable frequencies are observed. In other words, the LCB polymer undergoes a process of periodic stretched–folded–stretched state transition and rotation, whose period is obtained by fitting temporal changes on the orientation to a periodic function. In addition, the impact induced by random and fast motions of arms and the backbone will descend as the shear rate increases. By analyzing the period of rotation behavior of LCB polymers, we find that arms have a function in keeping the LCB polymer’s motion stable. Meanwhile, we find that the rotation period of the LCB polymer is mainly determined by the conformational distribution and the non-shrinkable state of the structure along the velocity-gradient direction. Secondly, structural properties are numerically characterized by the average gyration tensor of the LCB polymer. The changes in gyration are in accordance with the LCB polymer rolling when varying the shear rate. By analyzing the alignment of the LCB polymer and comparing with its linear and star counterparts, we find that the LCB polymer with very long arms, like the corresponding linear chain, has a high speed to reach its configuration expansion limit in the flow direction. However, the comb polymer with shorter arms has stronger resistance on configuration expansion against the imposed flow field. Moreover, with increasing arm length, the comb polymer in shear flow follows change from linear-polymer-like to capsule-like behavior.

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Relaxation Dynamics of Entangled and Unentangled Multiarm Polymer Solutions: Experiment

Cited by 13 publications

References 17 publications

Rheology and phase behavior of dense casein micelle dispersions

Rheology and phase behavior of dense casein micelle dispersions

Effect of n‐Alkyl Side Chain Length on the Thermal and Rheological Properties of PolyN‐(3‐(alkylamino)‐N‐(3‐(isopropylamino)‐3‐oxopropyl)acrylamide) Homopolymers

Dynamical and Structural Properties of Comb Long-Chain Branched Polymer in Shear Flow

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