Preparation by direct mixing and characterization of graphene nanoplatelet filled poly(dimethyl siloxane) composites

The present study investigated the effect of GN nanoplatelets on the properties of PDMS composites, prepared by direct mixing, using sonication. The calculation of the ratio of intensities of D (1350 cm−1) and G (1580 cm−1) bands (ID/IG), recorded by RAMAN spectroscopy, suggested an increase in carbon defects, upon the incorporation of grapheme into the PDMS matrix. This effect was attributed to the sonication procedure applied to the mixture. The thermal stability of the composites deteriorated, especially for higher GN concentrations (0.8 and 1 phr), as detected by thermogravimetric analysis (TGA). As to their mechanical properties, the tensile strength was enhanced up to 69% for composites reinforced with 0.5 phr GN, whereas the elongation at break increased for all composites, along with the modulus of elasticity, which improved especially at higher GN content (0.5 and 0.8 phr). The incorporation of GN nanoplatelets affected the elastomeric network, restricting the swelling of specimens immersed in toluene, especially for the 0.5 phr GN composite. Membranes of PDMS composites reinforced with 0.5 phr and 1 phr GN, exhibited a decrease in oxygen permeability of 28% and 53% respectively, in comparison with unreinforced PDMS specimens.