title: Revealing nanocomposite filler structures by swelling and small-angle X-ray scattering.
abstract: Polymer nanocomposites are used widely, mainly for the industrial application of car tyres. The rheological behavior of such nanocomposites depends in a crucial way on the dispersion of the hard filler particles - typically silica nanoparticles embedded in a soft polymer matrix. It is thus important to assess the filler structure, which may be quite difficult for aggregates of nanoparticles of high polydispersity, and with strong interactions at high loading. This has been achieved recently using a coupled TEM/SAXS structural model describing the filler microstructure of simplified industrial nanocomposites with grafted or ungrafted silica of high structural disorder. Here, we present an original method capable of reducing inter-aggregate interactions by swelling of nanocomposites, diluting the filler to low-volume fractions. Note that this is impossible to reach by solid mixing due to the large differences in viscoelasticity between the composite and the pure polymer. By combining matrix crosslinking, swelling in a good monomer solvent, and post-polymerization of these monomers, it is shown that it is possible to separate the filler into small aggregates. The latter have then been characterized by electron microscopy and small-angle X-ray scattering, confirming the conclusions of the above mentioned TEM-SAXS structural model applied directly to the highly loaded cases.
authors.affiliation: Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, F-34095 Montpellier, France and Manufacture Française des Pneumatiques MICHELIN, Site de Ladoux, 23 place des Carmes Déchaux, F-63 040 Clermont-Ferrand, France. marc.couty@fr.michelin.com.
authors.forename: Guilhem P
authors.initials: GP
authors.lastname: Baeza
authors.affiliation: Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, F-34095 Montpellier, France.
authors.forename: Anne-Caroline
authors.initials: AC
authors.lastname: Genix
authors.affiliation: Manufacture Française des Pneumatiques MICHELIN, Site de Ladoux, 23 place des Carmes Déchaux, F-63 040 Clermont-Ferrand, France. marc.couty@fr.michelin.com.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Paupy-Peyronnet
authors.affiliation: Manufacture Française des Pneumatiques MICHELIN, Site de Ladoux, 23 place des Carmes Déchaux, F-63 040 Clermont-Ferrand, France. marc.couty@fr.michelin.com.
authors.forename: Christophe
authors.initials: C
authors.lastname: Degrandcourt
authors.affiliation: Manufacture Française des Pneumatiques MICHELIN, Site de Ladoux, 23 place des Carmes Déchaux, F-63 040 Clermont-Ferrand, France. marc.couty@fr.michelin.com.
authors.forename: Marc
authors.initials: M
authors.lastname: Couty
authors.affiliation: Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, F-34095 Montpellier, France.
authors.forename: Julian
authors.initials: J
authors.lastname: Oberdisse