The use of dielectric spectroscopy for the characterization of polymer-induced flocculation of polystyrene particles

The use of dielectric spectroscopy in the investigation of the effect of polymer choice on the flocculation of polystyrene particles

“…In studies of the α relaxation of colloidal suspensions, Lyklema et al [18] and Kijlstra et al [26] have argued that unexpectedly high magnitudes of the dielectric dispersion were caused by the presence of particle aggregates in the suspensions. Although these studies did not examine the influence of flocculation on the dielectric dispersion, they do support the findings of increased dispersion magnitude due to flocculation reported in Christensen and Keiding [25]. The present study assesses the potential of DS to characterize the process in terms of flocculation mechanisms.…”

“…4 suggests a decrease in floc size at this polymer dosage, the decrease in τ found at dosages above 0.9 eq/eq cannot be caused by deflocculation. Previously, we studied the dielectric relaxation of polystyrene particles flocculated with polyDADMAC polymer, and found similar behavior at several particle volume fractions [25]. It was argued that the decrease in τ was caused by the formation of aggregates with relaxation times too high to be observed in the measured frequency range.…”

“…This, combined with the large and open aggregates found using the Zetag 7867FS40 polymer, suggests that the formation of polymeric patches is important to the flocculation process. A previous study, in which suspensions of the polystyrene particles used in this study were flocculated using polyDADMAC, found that flocculation by charge neutralization could not account for the flocculation process [25]. It was argued that the difference in distance between charges on the polymer and on the particle surface resulted in patch flocculation.…”

“…The permittivity spectra were measured by dielectric spectroscopy in a four-electrode cell that has been described elsewhere [25]. A Solartron 1260 impedance analyser was used to measure the impedance in the frequency range 1 kHz to 1 MHz.…”

“…In a previous paper, we used DS to study the flocculation of polystyrene particles with a cationic polymer [25]. We found that the characteristic time constant of the α relaxation increased when flocculation was initiated, and that the magnitude of the dielectric dispersion decreased due to a reduction in particle charge.…”