Dynamics of Laponite solutions: An interpretation within the coupling model scheme

Zulian, Laura; Ruzicka, Barbara; Ruocco, G.; Capaccioli, S.

doi:10.1016/j.jnoncrysol.2007.03.027

Cited by 6 publications

(3 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was reported in an earlier work that t c is concentration dependent for Laponite suspensions and that the value of t c at higher concentrations (C L > 1.5% w/v) is approximately 20 µsec [29]. Remarkably, the estimated value of the primitive relaxation time τ 0 (i.e.…”

Section: Resultsmentioning

confidence: 86%

“…In the absence of coupling at short times t < t c , the relaxation process is unaffected by many-body dynamics and the system relaxes with a relaxation time τ 0 . However, many-body coupling at long times t > t c leads to a fractional decay of φ(t) with stretched exponential relaxation [7,32]. The microscopic relaxation rate W 0 is related to the diffusion coefficient D 0 of a single relaxation unit by W 0 = (D 0 q 2 ) with D 0 = d 2 s /τ 0 .…”

Section: Sample Preparation and Experimental Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Characteristics of the secondary relaxation process in soft colloidal suspensions

Saha¹,

Joshi²,

Bandyopadhyay³

2015

EPL

View full text Add to dashboard Cite

A universal secondary relaxation process, known as the Johari-Goldstein (JG) β-relaxation process, appears in glass formers. It involves all parts of the molecule and is particularly important in glassy systems because of its very close relationship with the α-relaxation process. However, the absence of a J-G β-relaxation mode in colloidal glasses raises questions regarding its universality. In the present work, we study the microscopic relaxation processes in Laponite suspensions, a model soft glassy material, by dynamic light scattering (DLS) experiments. α and β-relaxation timescales are estimated from the autocorrelation functions obtained by DLS measurements for Laponite suspensions with different concentrations, salt concentrations and temperatures. Our experimental results suggest that the β-relaxation process in Laponite suspensions involves all parts of the constituent Laponite particle. The ergodicity breaking time is also seen to be correlated with the characteristic time of the β-relaxation process for all Laponite concentrations, salt concentrations and temperatures. The width of the primary relaxation process is observed to be correlated with the secondary relaxation time. The secondary relaxation time is also very sensitive to the concentration of Laponite. We measure primitive relaxation timescales from the α-relaxation time and the stretching exponent (β) by applying the coupling model for highly correlated systems. The order of magnitude of the primitive relaxation time is very close to the secondary relaxation time. These observations indicate the presence of a J-G β-relaxation mode for soft colloidal suspensions of Laponite.

show abstract

Section: Resultsmentioning

confidence: 86%

Section: Sample Preparation and Experimental Methodsmentioning

confidence: 99%

Characteristics of the secondary relaxation process in soft colloidal suspensions

Saha¹,

Joshi²,

Bandyopadhyay³

2015

EPL

View full text Add to dashboard Cite

show abstract

“…Aqueous suspension of smectite clay laponite is considered as a model soft glassy material that shows all the above mentioned characteristic features, 8 and hence is a subject of intense investigation over past decade. Various prominent studies on this system involve optical characterization to explore its relaxation dynamics [13][14][15][16][17][18][19][20] and phase behavior 15,[21][22][23][24] while various rheological tools, which essentially investigate shear flow behavior, have been employed to study aging under deformation field and thixotropic behavior. [25][26][27][28][29][30] In many applications, thin viscous and visco-elastic layers undergo tensile deformation.…”

Section: Introductionmentioning

confidence: 99%

Tensile Deformation and Failure of Thin Films of Aging Laponite Suspension

Shaukat

Joshi

Sharma

2009

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

In this paper we study deformation, failure and breakage of visco-elastic thin films of aging laponite suspension under tensile deformation field. Aqueous suspension of laponite is known to undergo waiting time dependent evolution of its micro-structure, also known as aging, which is accompanied by an increase in the elastic modulus and relaxation time. In the velocity controlled tensile deformation experiments, we observed that the dependence of force and dissipated energy on velocity and initial thickness of the film is intermediate to aNewtonian fluid and a yield stress fluid. For a fixed waiting time, strain at break and dissipated energy increased with velocity, but decreased with initial thickness. With increase in age, strain at break and dissipated energy showed a decrease suggesting enhanced brittle behavior with increase in waiting time, which may be caused by restricted relaxation modes due to aging. In a force controlled mode, decrease in strain at failure at higher age also suggested enhanced brittleness with increase in waiting time. Remarkably, the constant force tensile deformation data up to the point of failure showed experimental time-aging time superposition that gave an independent estimation of relaxation time and elastic modulus dependence on age.2

show abstract

Glass-Forming Substances and Systems

Ngai

2010

Partially Ordered Systems

View full text Add to dashboard Cite

Dynamics of Laponite solutions: An interpretation within the coupling model scheme

Cited by 6 publications

References 27 publications

Characteristics of the secondary relaxation process in soft colloidal suspensions

Characteristics of the secondary relaxation process in soft colloidal suspensions

Tensile Deformation and Failure of Thin Films of Aging Laponite Suspension

Glass-Forming Substances and Systems

Contact Info

Product

Resources

About