Carbon Black Networking in Elastomers Monitored by Dynamic Mechanical and Dielectric Spectroscopy

Abstract

The morphological structure of CB networks in elastomers and their flocculation dynamics under heat treatment and especially during vulcanization are analyzed by dynamic mechanical and dielectric spectroscopy. Dielectric spectra in the MHz range show that nanoscopic gaps between adjacent CB particles develop during heat treatment or vulcanization. These gaps are maintained by immobilized polymer layers acting as flexible bonds between the particles. Low‐frequency dielectric data indicate that the static percolation model qualitatively describes the dielectric properties of the conducting CB network on large length scales, but a superimposed kinetic aggregation process takes place on smaller length scales.

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

“…These effects result in the trapping and accumulation of charges at the polymer/silica interface. Charges can diffuse on the surface of individual NPs within aggregates, or on a larger scale on the surface of aggregates [27], processes which have been described theoretically by the interlayer model (ILM) [28,29]. The ionic conductivity has also been studied over the whole frequency range [27,30].…”

“…Charges can diffuse on the surface of individual NPs within aggregates, or on a larger scale on the surface of aggregates [27], processes which have been described theoretically by the interlayer model (ILM) [28,29]. The ionic conductivity has also been studied over the whole frequency range [27,30]. In a biphasic material, one may note that the measured conductivity is a global observable, which is related to the polymer, the filler via its surface conductivity, and to the spatial arrangement of the filler which may form conductive pathways of various sizes within the sample.…”

Micromechanical model for isolated polymer-colloid clusters under tension

“…It has been rejected by experimental studies in many materials such as disordered fiber networks [60], granular solids, and particulate packings [61]. However, in some materials the error associated to ILS is found to be sufficiently low so it can be adopted [4,5,28,[62][63][64][65][66][67]. Our recent studies show that the ILS assumption is relevant only in certain binary composites and the error associated to it varies based on the aggregation process [42,68].…”

“…There are different theories on contribution of clusters to the deformation-induced damage of the matrix, and rubber in particular. Some associate damage to the yielding and reformation of the clusters [26][27][28][29], some to gradual softening of the particle-particle bonds [30][31][32], and some to the changes in cluster sizes and structural rearrangement [33][34][35]. So far, no consensus on the micromechanics of PC clusters has emerged and, despite its ubiquity and significance, it remains far from understood; even the classification of interparticle forces is not agreed on.…”

Synergistic effect of graphene and silicon dioxide hybrids through hydrogen bonding self-assembly in elastomer composites

“…It's widely accepted that the peak value of tan d is a measurement of the energy dissipation in polymer composites during the mechanical-cyclic test. 45,46 Such energy dissipation is inversely proportional to the interfacial interaction between polymer and ller network which will substantially constrain and impair the mobility of polymer chains.…”