Correlation of mass fractal dimension and cluster size of silica in styrene butadiene rubber composites

Abstract

The morphology of the precipitated silica VN3 filled in styrene butadiene rubber was studied as a function of the volume fraction Φ by means of small-angle X-ray scattering experiments. The wide q-range of 0.008 nm(-1)<q<1 nm(-1) probes the structures of the primary particles, the clusters, and resolves a part of the larger clusters of the silica. The diameter of the primary particles and their surface roughness are independent from the silica concentration. The size of the clusters and the corresponding aggregation number depend on Φ. This observation could be ascribed to external mechanical forces because of the mixing process and to growing cluster-cluster interactions with increasing filler fraction. In contrast the mass fractal dimension does not depend on Φ, and by that means experimentally proving that there is not necessarily a correlation between the mass fractal dimension and the cluster size.

Multiscale structure of super insulation nano-fumed silicas studied by SAXS, tomography and porosimetry

“…[1] While the former are believed to be indivisible gatherings of elementary particles, the latter consist of clusters of weakly bounded aggregates that can be "broken" by applying mechanical stress, e.g. in nanocomposites, by "internal" mixing [2][3][4] or in solution via stirring [5] and sonication. [6,7] When loosely packed, these nano-architectured materials are essentially composed of air (>80%) [8][9][10][11][12] with typical pore sizes not exceeding 200 nm, making them excellent candidates for thermal insulation applications.…”

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

“…Considering these particles as homogeneous spheres, the radius p R can be related with the radius of gyration Table 3 and Table 4. 15,19,20 . The main reason could be related to the fact that the pre-factors H [1][2][3][4] are not correlated among each other.…”

“…On the other hand, SAXS data is highly representative due to the macroscopic sample size that is probed but these data have to be fitted with a suitable model function in order to obtain structural information. Several structural studies in SBR and NR filled compounds have been undertaken by different groups [15][16][17][18][19][20] . However, due to the complex hierarchical morphologies associated to the fillers and their diversity of sizes, to date there is no analytical model consistently describing the structure at all length scales.…”

Silica dispersion in styrene butadiene rubber composites studied by synchrotron tomography

“…The latter result is, however, surprising on first glance. We will try to explain it by using scattering studies of the average cluster size in the nanometer range [7]. There, it was observed that the average cluster size decreases with increasing particle fraction Φ due to the influence of enhanced mechanical shear forces during the mixing process.…”

“…In general, there is a multitude of possible reasons causing the different material responses to an external perturbation. It ranges from the case of well dispersed nanoparticles, where different interaction potentials between the polymer and the surface may be responsible for the particular response of the composite [1][2][3][4][5][6], up to particle dominated behavior in the case of very high particle fractions and hierarchically structured particles [1][2][3][4][5][6][7].…”