Influence of Water and Filler Content on the Dielectric Response of Silica-Filled Rubber Compounds

Abstract

We present in this work a systematic study to analyze the influence of water and filler content on the dielectric response of silica-filled rubber compounds. For nanoparticle-filled polymers an additional dielectric process is usually observed in the loss dielectric spectra at frequencies lower than the alpha (α) or segmental relaxation. This process has generated some controversy in the literature due to the different (sometimes contradictory) interpretations given to explain its physical origin. We demonstrate, by means of dielectric spectroscopy in combination with thermal analysis, that this low-frequency process is compatible with a MWS process enhanced by the presence of water molecules at the silica surface. We show that the frequency of the maximum for this process is strongly affected by the amount of water attached to the silica particles. The dielectric response of the MWS process is rationalized by means of a simple interlayer model (IL). In addition, we also study the influence of water and filler content on the segmental dynamics and discuss possible mechanisms for the filler−polymer interaction.

Depercolation of aggregates upon polymer grafting in simplified industrial nanocomposites studied with dielectric spectroscopy

“…Times for the MWS1-process are given in the SI with a description in terms of the interlayer model [28,29]. Within error bars, we observe that the segmental dynamics is not modified by the presence of filler up to the highest silica fraction, in agreement with ref [21]. The impact of grafting with %D3 from 0 to 100% is shown in the inset of Figure 3 for Φ si ≈ 8.5%v.…”

“…Polymer in contact with NP surfaces may form immobilized, sometimes referred to as "glassy", layers which are mainly detected by NMR [13,23]. On larger scales, at high temperature (above the glass transition), the occurrence of a Maxwell-Wagner-Sillars (MWS) process has been reported in several composite systems using broadband dielectric spectroscopy (BDS) [21,[24][25][26]. MWS processes are related to polarization effects due to charge carrier diffusion through the different phases of the nanocomposites.…”

Viscoelastic and dielectric properties of composites of poly(vinyl butyral) and alumina particles with a high filling degree

“…The experimental data of Kummali et al [34] using so-called nano-dielectric spectroscopy do not give any indication of an immobilized polymer layer around silica nanoparticles in styrene-butadiene-rubber (SBR). The influence of water on the Maxwell-Wagner-Sillars polarization in silicafilled styrene-butadiene rubber compounds was investigated by Otegui et al [35]. A larger water content is associated with a shift of the relaxation peak to higher frequencies.…”

Determination of Filler Structure in Silica-Filled SBR Compounds by Means of Saxs and Afm

“…For automobile tires SBR rubbers are often reinforced by the addition of fillers such as carbon black or silica particles [1][2][3][4][5][6] . In particular, activated silica reinforcement plays an important role in improving the properties of the SBR compounds [7][8][9][10] . Moreover, one of the key factors that determine the final properties of these filled compounds is commonly related to the filler structures 11 .…”