Dynamical mechanical properties of gelling colloidal disks

The viscoelastic properties of gelling Laponite clay suspensions were studied by measuring the time evolution of the frequency dependent shear modulus. At a well defined gel time the loss and storage modulus have a power law frequency dependence with the same exponent Δ=0.55. The exponent is compared with theoretical predictions for fully flexible and locally rigid gels. After the gel point the shear modulus continues to evolve and a stable state was not reached in the experiments. The loss modulus of the gel increases with decreasing frequency at low frequencies, indicating the presence of slow relaxation processes. The rate of gelation increases strongly with increasing ionic strength.

[1]  J. Ramsay,et al.  Swelling and dispersion of smectite clay colloids: determination of structure by neutron diffraction and small-angle neutron scattering , 1990 .

[2]  James E. Martin,et al.  The Sol-Gel Transition in Chemical Gels , 1991 .

[3]  P. Levitz,et al.  Sol–gel transition of colloidal suspensions of anisotropic particles of laponite , 1995 .

[4]  W. Vos,et al.  Structure and Formation of a Gel of Colloidal Disks , 1998 .

[5]  T. Zemb,et al.  Ultrasmall- and small-angle X-ray scattering of smectite clay suspensions , 1994 .

[6]  E. Amis,et al.  Dynamic viscoelastic characterization of sol-gel reactions , 1990 .

[7]  C. Michon,et al.  Concentration dependence of the critical viscoelastic properties of gelatin at the gel point , 1993 .

[8]  D. Durand,et al.  Dynamic Viscoelastic Characterization of a Polyurethane Network Formation , 1996 .

[9]  H. Damme,et al.  On Viscoelastic, Birefringent, and Swelling Properties of Laponite Clay Suspensions: Revisited Phase Diagram , 1998 .

[10]  M. Kawai,et al.  Viscoelastic and SAXS investigation of fractal structure near the gel point in alginate aqueous systems , 1992 .

[11]  N. C. Lockhart.  Electrical properties and the surface characteristics and structure of clays. I. Swelling clays , 1980 .

[12]  H. von Gunten,et al.  Light scattering characterization of laporite sols , 1990 .

[13]  J. Gabriel,et al.  Observation of Nematic Liquid-Crystal Textures in Aqueous Gels of Smectite Clays , 1996 .

[14]  H. Henning Winter,et al.  Analysis of Linear Viscoelasticity of a Crosslinking Polymer at the Gel Point , 1986 .

[15]  P. Levitz,et al.  Phase diagram of colloidal dispersions of anisotropic charged particles : equilibrium properties, structure, and rheology of laponite suspensions , 1995 .

[16]  Dudley W. Thompson,et al.  The nature of laponite and its aqueous dispersions , 1992 .

[17]  K. Norrish,et al.  The swelling of montmorillonite , 1954 .

[18]  L. Matějka.  Rheology of epoxy networks near the gel point , 1991 .

[19]  P. Lindner,et al.  Small-angle neutron scattering investigations of the structure of thixotropic dispersions of smectite clay colloids , 1993 .

[20]  Jean-Pierre Hansen,et al.  Statistical model for the structure and gelation of smectite clay suspensions , 1997 .

[21]  I. Webman,et al.  Elastic Properties of Random Percolating Systems , 1984 .

[22]  J. Piau,et al.  YIELD STRESS THIXOTROPIC CLAY SUSPENSION : INVESTIGATIONS OF STRUCTURE BY LIGHT, NEUTRON, AND X-RAY SCATTERING , 1997 .

[23]  D. Bonn,et al.  Laponite: What Is the Difference between a Gel and a Glass? , 1999 .

[24]  J. Ramsay,et al.  Colloidal properties of synthetic hectorite clay dispersions: I. Rheology , 1986 .

[25]  N. Willenbacher.  Unusual Thixotropic Properties of Aqueous Dispersions of Laponite RD , 1996 .