Low permeability styrene butadiene rubber/boehmite nanocomposites modified with tannic acid

• Natural tannic acid is efficient in improving the interface of rubber/boehmite composites.
• The rubber/boehmite composites modified by tannic acid possess the combination of high strength and low modulus.
• The modified rubber nanocomposites with high boehmite loading exhibit significantly lowered gas permeability.

Layered inorganics are promising in the fabrication of elastomeric nanocomposites with enhanced barrier property. Recently, boehmite (BM) nanoplatelets have emerged as alternative layered inorganics to clays and double hydroxylates as the functional reinforcement for rubbers. In the present paper, natural tannic acid (TA) is introduced as a novel interfacial modifier in BM-filled styrene–butadiene rubber (SBR) nanocomposites. The modification mechanism and interfacial interactions in the nanocomposites are fully characterized. Due to the strengthened interface and the comparatively finer dispersion state of BM in the nanocomposites, significantly enhanced mechanical properties are found in the modified system. At higher BM loadings (higher than 40 phr), the modified system possesses a much lower gas permeability compared with the unmodified counterpart. Very interestingly, the TA-modified SBR/BM nanocomposites exhibit high tensile strength yet impressively low moduli compared with previously reported rubber nanocomposites filled with other nanofillers.

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