The effect of graphene oxide on thermomechanical and permeability properties of poly(dimethyl siloxane) composites

The effect of graphene oxide (GO) on the properties of composites with hydroxyl-terminated poly(dimethyl siloxane) (PDMS) matrices, prepared by solution mixing, using tetrahydrofuran (THF) as a solvent, were examined. Viscosity measurements during the vulcanization reaction, using a Brookfield viscosimeter, revealed that GO increases the viscosity of the system, in comparison with the unreinforced PDMS, proportionally to its concentration. The calculation of D and G bands ratio (ID/IG) at 1350 and 1580 cm−1 respectively, using RAMAN spectroscopy, showed more defects in graphene nanoplatelets incorporated in the PDMS nanocomposites. By Differential Scanning Calorimetry (DSC), a slight decrease in glass transition and melting temperatures of PDMS was observed. The thermal stability of composites was significantly improved, especially at higher GO concentrations (0.5 and 1 phr), as it was detected by thermogravimetric analysis (TGA). Also, the tensile strength of composites was enhanced, up to 113%, for samples reinforced with 1 phr GO. The elongation at break was increased, whereas no effect on the modulus of elasticity was observed. A decrease in oxygen permeability of 38% and 15% was measured in membranes made of composites containing 0.5 phr and 1 phr GO respectively. The increase in swelling after immersion of composites in toluene was explained by the fact that this phenomenon is not only related with the crosslinking density of the elastomer but also with the increased absorption properties of GO particles, due to the sonication treatment in THF during the preparation process of the composite, which might contribute to this effect.