Izlaganje sa skupa

The Stability of Silica Hydrosols Under the Influence of Polymer Adsorption

Erwin Killmann ; Lehrstuhl fur Makromolekulare Stoffe, Institut fur Technische Chemie der Technischen Universitat Munchen, 8046 Garching, Bundesrepublik Deutschland

Sažetak

The stability of standardized, well dispersed silica (Aerosil).
hydrosols at different pH has been studied using a self-constructed
laser photosedimentometer. Ultrasonication was proved most suitable
for providing reproducible standardized hydrosols, which
were characterized by determining the viscosity/concentration dependence
in a cylinder viscosimeter, the sedimentation coefficient
in an analytical ultracentrifuge, the partial specific volume in an
oscillating U-tube of a high precision density meter, the translational
diffusion coefficient with a photon correlation spectrometer
and the dimension and shape of the silica particles by transmission
electron microscopy.
The Aerosil hydrosols can be reproducibly flocculated with
polyethyleneglycols of molar mass 6000 and 40 000, even in the
absence of electrolyte at high pH, when the sol concentration is
sufficiently high. Reproducibility necessitates standardized mixing
procedures of sol and polymer.
The laser-photosedimentometer provides suitable parameters
for the characterization of the turbidity- and sedimentation behaviour
of the flocculated sols.
The effects of different mixing procedures have been tested
and the influence of titration and mixing time, intensity and time
of stirring can be analyzed quantitatively as well, as the relationships
of the characterizing parameters on polymer coverage, molecular
weight and silica concentration.
From these dependences and by using additional rheological
measurements it was possible to identify the classical model of
polymer bridging as the most likely mechanism for the destabilization

Ključne riječi

Hrčak ID:

194190

URI

https://hrcak.srce.hr/194190

Datum izdavanja:

9.11.1983.

Posjeta: 970 *