Determination of filler structure in silica-filled SBR compounds by means of SAXS and AFM

The structure of the silica particles network in two different solution styrene-butadiene rubbers (S-SBRs) was studied by means of small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). S-SBR compounds with different silica contents were analyzed in comparison with their oil extended counterparts. A study into the application of SAXS experiments was defined to quantify the structures of silica primary particles and clusters in filled rubber compounds up to very high levels of filler content. We propose a modified structure model that is physically more sound than the widely used Beaucage model and that leads to more robust quantification of the silica structures. In addition, an independent characterization of the filler structure was performed by means of AFM. The cluster and particle sizes deduced from both techniques are in close agreement, supporting the proposed approach. The synergetic application of SAXS and AFM allows a consistent and robust characterization of primary particles and clusters in terms of size and structure. These results were compared and discussed in the framework of previously published works.The authors gratefully acknowledge the support of the Spanish Ministry of Education(MAT2012-31088), Basque Government (IT-436-07), and Luxembourgish Fonds National de la Recherche. Financial support from European Union–funded ‘‘ European soft matter infrastructure’’(reference 262348 ESMI) is also acknowledged.Peer Reviewe