Magadiite/styrene-butadiene rubber composites for tire tread applications: Effects of varying layer spacing and alternate inorganic fillers

Magadiite (MGD), a synthetic layered silicate (Na2Si14O29 - 9H(2)O) with surface chemistry similar to precipitated silica, was cation-exchanged with three different organic cations to explore the effect of varying MGD layer spacing on the mechanical properties of MGD-based styrene-butadiene rubber (SBR) composites. This work also compares the mechanical properties of MGD/SBR composites with those formulated with montmorillonite (MMT) and precipitated silica. Dodecylpyridinium (DP+) produces greater expansion of MGD layers than cetyltrimethylammonium (CTA(+)); the resulting DP-MGD/SBR composites have greater yield strain, toughness, and rubbery storage modulus than comparable CTA-MGD/SBR composites. MGD treated with hexadecylammonium (HDA(+)) has the greatest layer spacing, but the HDA-MGD layers collapse upon melt-blending with SBR. CTA-treated MMT (CMMT) exfoliates in aqueous suspension, but the platelets re-stack upon drying and during melt-blending with SBR. The presence of exfoliated and/ or disordered platelet stacks in CMMT/SBR probably accounts for its higher tensile and dynamic moduli compared to MGD-and silica-based SBR composites. Dynamic mechanical properties are used to predict tire tread performance metrics for these composites.(C) 2017 Wiley Periodicals, Inc.