Strain amplitude response and the microstructure of PA/clay nanocomposites

Wan, Tong; Clifford, M.J.; Gao, Fengge; Bailey, A. S.; Gregory, Duncan H.; Somsunan, Runglawan

doi:10.1016/j.polymer.2005.04.105

Cited by 43 publications

(25 citation statements)

References 21 publications

(13 reference statements)

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“…This overshoot reaches a maximum at shear strains of 5-10 % and is followed by shear thinning behaviour at even larger strains. Similar overshoots were previously observed in polyamide-6 clay nanocomposites (Wan et al 2005) and have been attributed to and can be modelled by the different amplitude dependence of the rate Fig. 1 Amplitude sweeps of normalised storage modulus G /G 0.5 % and loss modulus G /G 0.5 % measured at 2π rad s −1 of (a) unfilled PC 2205 at temperatures 160-260 • C and of (b) PC-MWCNT (3 wt%) 2205 at temperatures 160-300 • C. The vertical dashed line indicates the linear viscoelastic limit of cluster formation relative to that of cluster destruction (Hyun et al 2011).…”

Section: Resultssupporting

confidence: 88%

Viscoelastic melt rheology and time–temperature superposition of polycarbonate–multi-walled carbon nanotube nanocomposites

2013

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This work investigates the linear and non-linear viscoelastic melt rheology of four grades of polycarbonate melt compounded with 3 wt% Nanocyl NC7000 multiwalled carbon nanotubes and of the matching matrix polymers. Amplitude sweeps reveal an earlier onset of nonlinearity and a strain overshoot in the nanocomposites. Mastercurves are constructed from isothermal frequency sweeps using vertical and horizontal shifting. Although all nanocomposites exhibit a second plateau at ∼10 5 Pa, the relaxation times estimated from the peak in loss tangent are not statistically different from those of pure melts estimated from cross-over frequencies: all relaxation timescales scale with molar mass in the same way, evidence that the relaxation of the polymer network is the dominant mechanism in both filled and unfilled materials. Non-linear rheology is also measured in large amplitude oscillatory shear. A comparison of the responses from frequency and amplitude sweep experiments reveals the importance of strain and temperature history on the response of such nanocomposites.

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Section: Resultssupporting

confidence: 88%

Viscoelastic melt rheology and time–temperature superposition of polycarbonate–multi-walled carbon nanotube nanocomposites

2013

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“…As expected, the maximum strain to which the linear viscoelastic domain extends was observed to be decreasing while increasing the clay concentration [86]. Aubry et al [87] first observed g c ff À1 in polyamide-12 layered silicate.…”

Section: Clay Nanocompositessupporting

confidence: 62%

Melt rheology of organoclay and fumed silica nanocomposites

Cassagnau

2008

Polymer

453

327

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The objective of the present work is to investigate, from the open literature, the recent developments in the rheology of silica and organoclay nanocomposites. In particular, this paper focuses on general trends of the linear viscoelastic behaviour of such nanocomposites. Hence, the variations of the equilibrium shear modulus and critical strain (limit of linearity), which depend on power laws of the volume fraction of particles, are discussed as filler fractal structure. In the third section, the strong nonlinearity behaviour (Payne effect) of filled polymers has been discussed in terms of filler nature. Typically two mechanisms arise to depict the linear solid-like behaviour and the Payne effect: particleeparticle interactions is the dominant mechanism in fumed silica nanocomposites whereas particleepolymer interaction is the dominant one in colloidal silica nanocomposites at identical filler concentrations. However, these interactions are balanced in each nanocomposite systems by the silica surface treatments (chain grafting, silane modification) and the molecular weight of the matrix. Finally, we aim to unify the main findings of the literature on this subject, at least from a qualitative point of view.We finally report on the thixotropy and modulus recovery after a large deformation in steady and dynamic shear conditions. Following this, the nonlinear rheological properties of nanocomposite materials have been discussed. The discussion is particularly focused on the effect of flow history (transient shear experiments) on the orientationedisorientation of clay platelets. Actually, the linear and nonlinear rheological properties are consistent with a network structure of a weakly agglomerated tactoids. As far as exfoliated clay nanocomposites are concerned, the interparticle interaction is the dominant effect in the nonlinearity effect.

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“…The region of linear viscoelastic behaviour for the matrix extends up to 40% strain, but falls down to lower than 1% when whiskers are added to nanocomposites prepared with 0 and 1% MPS. It is worth noting that non-linear viscoelastic behaviour is often observed in the case of polymeric matrix reinforced by nanofillers such as clay [24], fumed silica [25], carbon nanotubes [26] and so on. A number of different local mechanisms related to the change in network structure have been proposed to explain this phenomenon [27].…”

Section: Strain Amplitude Response Of the Nanocomposite In The Melt Smentioning

confidence: 99%

Melt rheology of nanocomposites based on acrylic copolymer and cellulose whiskers

Mabrouk

Magnin

Belgacem

et al. 2011

Composites Science and Technology

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Strain amplitude response and the microstructure of PA/clay nanocomposites

Abstract: Abstract:PAn nanocomposites with various clay loadings were prepared by melt compounding in a twin extruder. Exfoliation of clay in a PA matrix was confirmed by X-ray

Cited by 43 publications

References 21 publications

Viscoelastic melt rheology and time–temperature superposition of polycarbonate–multi-walled carbon nanotube nanocomposites

Viscoelastic melt rheology and time–temperature superposition of polycarbonate–multi-walled carbon nanotube nanocomposites

Melt rheology of organoclay and fumed silica nanocomposites

Melt rheology of nanocomposites based on acrylic copolymer and cellulose whiskers

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