Poly(styrene-co-butadiene)/Maghnia-Organo-Montmorillonite Clay Nanocomposite. Preparation, Properties and Application as Membrane in the Separation of Methanol/Toluene Azeotropic Mixture by Pervaporation

Abstract

In order to improve the thermal and mechanical properties of poly(styrene-co-butadiene) (SBR) to use it as a pervaporation membrane in the separation of the azeotropic mixture toluene/methanol, poly(styrene-co-butadiene) crosslinked Maghnia-organo-montmonrillonite (CSBR/OMMT), a nanocomposite of different compositions was first prepared by a solvent casting method. SBR was crosslinked in situ in the presence of OMMT nanoparticles by an efficient vulcanization technique using sulfur as a crosslinking agent and zinc diethyldithiocarbamate as a catalyst. The structure and morphology of the hybrid materials obtained were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope analysis. The thermal properties of these hybrid materials were studied by differential scanning calorimetry and thermogravimetric analysis/thermal differential analysis. The mechanical properties were studied by strength measurements. The results obtained occurred when the OMMT was incorporated in the CSBR matrix; a significant increase in the glass transition temperature of the SBR was observed which passed from −27 °C for virgin SBR to −21.5 °C for that containing 12 wt% of OMMT. The addition of OMMT nanoparticles to CSBR also improved the mechanical properties of this copolymer. When the OMMT content in the CSBR varied from 0 to 15% by weight, the tensile strength, the elongation at the nose and the modulus at 100% elongation increased from 3.45 to 6.25 MPa, from 162, 17 to 347.20% and 1.75 to 3.0 MPa, respectively. The results of pervaporation revealed that when the OMMT content varied between 3% and 12%, a significant increase in the total flux, the separation factor and the separation index by pervaporation increased from 260.67 to g m−2 h−1, 0.31 to 1.43, and 0.47 to 113.81 g m−2 h−1, respectively.