Nonlinear viscoelastic properties and change in entanglement structure of linear polymer

Isono, Yoshinobu; Kamohara, Toshihiro; Takano, Atsushi; Kase, Toshio

doi:10.1007/bf00366665

Cited by 21 publications

(30 citation statements)

References 23 publications

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“…The apparatus used was biaxial rheometer made by ourselves 15,16) . It is equipped with servo-controlled oilhydraulic actuator (JT Toshi), a load cell (LRM-50K, Nihon Tokushu Sokki), and a cantilever spring type displacement transducer (CE-10, Tokyo Sokki).…”

Section: Measurementmentioning

confidence: 99%

“…Such a situation can be realized easily by reversing double-step deformation in compression. Hence the possible method may be observation of differential dynamic modulus (DDM) [9][10][11][12][13][14][15][16][17][18] measured by small oscillatory deformation superposed on large compression and recovery. The new method proposed here for evaluation of filler network is explained schematically in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Novel Characterization of Filler Network in Rubber Materials Using Differential Dynamic Modulus in Large Compression and Recovery

et al. 2007

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Rubber materials are made of two networks, chemical and filler networks. The networks are characterized usually by overall network density estimated at equilibrium condition. However, rubbers are used in nonlinear conditions where the filler network may change from the one at equilibrium. We need additional information on the filler network. Hence, differential dynamic modulus (DDM) in large compression (eϭϪ0.1) and recovery (eϭ0) were measured for the samples filled with carbon blacks (CB) having different primary particle sizes. The change in EЈ for unfilled sample was reversible in large compression followed by recovery, while those for filled samples were irreversible, showing change in filler network in large deformation. The differences in DDM at the recovered and the initial states were compared for characterization of the filler network. The difference for the sample filled with smaller CB was larger than the one with larger CB. The results show that the rubber filled with CB having smaller particle size makes weaker filler network. In addition, we observed the restoration behavior of the filler network structure. Recovery of filler network ruptured due to large compression and recovery in shape was attained at a time scale depending on particle size. The characteristic time was found to increase with increase in the CB particle size. It was concluded that the restoration process of CB filler network is based on diffusion of CB aggregate.

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Section: Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Novel Characterization of Filler Network in Rubber Materials Using Differential Dynamic Modulus in Large Compression and Recovery

et al. 2007

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“…Figure 7 shows the change in the storage modulus with time after cessation of the shearing. (These experiments were conducted only for the two highest molecular weight samples, because the instrumental lag time 38 (6) where G' ∞ is the equilibrium value (t ~ ∞) of the storage modulus at the imposed frequency, A G is a constant, and τ R,G measures the time for recovery of G'. The results for the two PB solutions are included in Figure 7.…”

Section: Non-linear Shear Flowmentioning

confidence: 99%

“…The shear thinning is ascribed to a loss of entanglements, resulting from the flow-induced orientation of the chains. [1][2][3][4][5][6][7] Although this loss is reversible, the time scale for entanglement recovery can be very slow. This allows advantage to be taken of the "shearmodified" state during polymer processing; for example, elastic effects such as die swell are much weaker for some time after the shearing.…”

Section: Introductionmentioning

confidence: 99%

Recovery of Shear-Modified Polybutadiene Solutions

Roland

Robertson²

2006

Rubber Chemistry and Technology

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We have investigated the recovery of the overshoot in the transient viscosity, the first normal stress coefficient, and the dynamic modulus for entangled polybutadiene solutions subjected to nonlinear shear flow. The molecular-weight dependences of the various time scales (linear viscoelastic relaxation time, entanglement recovery time, and timescale for decay of stress following cessation of shearing) are all consistent with the usual 3.4 power law. Nevertheless, the time for recovery of the stress overshoot and plateau value of the dynamic modulus were substantially longer (by as much as two orders of magnitude) than the linear viscoelastic relaxation time calculated from the Newtonian viscosity and the equilibrium recoverable compliance. These results indicate that complete entanglement recovery requires cooperative chain motions over a length scale exceeding that associated with linear relaxation. This persistence of a disentangled state means that a state of low viscosity and reduced elasticity is retained for an extended time, suggesting that shear modification can be used to facilitate the processing of polymers.

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“…2,20 The disentanglement of polymers subjected to steady shearing is wellestablished experimentally. [21][22][23][24][25][26][27] In a steady shearing experiment, the loss of entanglements leads to a maximum in the stress ("stress overshoot") at high shear rates. Stress overshoots are also observed in dilute polymer solution, 28 as well as melts of low molecular weight (unentangled) polymers, 29,30 due to molecular orientation.…”

Section: Introductionmentioning

confidence: 99%

Reentanglement Kinetics in Sheared Polybutadiene Solutions

et al. 2004

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Interrupted shear measurements were used to follow the reentanglement kinetics and associated molecular weight dependence for solutions of near-monodisperse polybutadiene (PB). The timedependent recovery of the overshoot in the shear stress was measured for PB having weight-average molecular weights (M w) equal to 61, 90, 107, and 167 kg/mol, corresponding to a range of 17-47 entanglements per chain in solution. The times for recovery of the stress overshoot were 1.5 decades longer (30 times greater) than the corresponding linear viscoelastic relaxation times, the latter determined from dynamic shear data or from stress relaxation following cessation of flow. Notwithstanding the differing time scales, the M w dependences for entanglement recovery and linear viscoelastic relaxation were equivalent (power law exponent ∼ 3.4).

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Nonlinear viscoelastic properties and change in entanglement structure of linear polymer

Cited by 21 publications

References 23 publications

Novel Characterization of Filler Network in Rubber Materials Using Differential Dynamic Modulus in Large Compression and Recovery

Novel Characterization of Filler Network in Rubber Materials Using Differential Dynamic Modulus in Large Compression and Recovery

Recovery of Shear-Modified Polybutadiene Solutions

Reentanglement Kinetics in Sheared Polybutadiene Solutions

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