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Oud-Heverlee, Belgium

Xu X.,Soft Matter and Biophysics Group | Xu X.,Nanjing University | Cuautle J.J.A.F.,Soft Matter and Biophysics Group | Kouyate M.,Soft Matter and Biophysics Group | And 10 more authors.
Journal of Physics D: Applied Physics | Year: 2016

The evolution of the elastic and thermal properties of a tetramethylorthosilicate (TMOS)-based gel that exhibits an extraordinary ringing effect when enclosed in a bottle is investigated during the sol-gel transition. The results demonstrate the feasibility of three proposed experimental methods for monitoring of gels during their formation. The shear stiffening evolution during gelation is monitored by ringing bottle, resonant acoustic spectroscopy and by an ultrasonic technique using piezo electric excitation and detection. The evolution of the longitudinal modulus and the thermal diffusivity of the gel during stiffening are simultaneously determined by a combined photoacoustic and photothermal method based on heterodyne diffraction detection of impulsive stimulated scattering by, respectively, a propagating acoustic wave grating and a decaying thermal expansion grating that were both thermo elastically generated using a pulsed laser. Also, the feasibility of an inverse photopyroelectric method and a hot ball technique to monitor the thermal transport efficiency and thermal impedance of a forming gel by tracking the thermal conductivity, the thermal diffusivity, and the thermal effusivity is demonstrated. The network polymerization and stiffening during the sol-gel transition in TMOS-gel corresponds with substantial changes in the shear acoustic velocity and in all thermal properties, while the longitudinal acoustic velocity is only weakly affected. © 2016 IOP Publishing Ltd. Source


Kouyate M.,Soft Matter and Biophysics Group | Flores-Cuautle J.J.A.,Soft Matter and Biophysics Group | Flores-Cuautle J.J.A.,CONACyT Research Fellow | Flores-Cuautle J.J.A.,Orizaba Institute of Technology | And 9 more authors.
International Journal of Thermophysics | Year: 2015

In this work, the impulsive stimulated scattering technique, in a heterodyne diffraction detection configuration (ISS-HD), was used to study the dependence of the speed of sound and the thermal diffusivity on the concentration of silver nanoparticles in water, to which also d-glucose and carboxymethyl cellulose were added, in order to reduce sedimentation. The ISS-HD results, which show a slight increase of thermal diffusivity with increasing concentration, were cross-validated with results obtained by the inverse photopyroelectric method and the hot ball technique. © 2015, Springer Science+Business Media New York. Source

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