Frictional microscopy of polymers and nanocomposites

The mechanical and frictional properties of polystyrene, polymethylmethacrylate and nanocomposites with montmorillonite were studied by using the microindentation technique and frictional microscopy. The micromechanical tests revealed a decrease in the modulus and microhardness of the composite compared with those of a neat polystyrene, with a minimum of their values at 1-3 wt.% of the filler, but a local maximum of the tensile modulus of the filled polymer arose and increased at the same filler concentration. The frictional microscopy revealed anisotropy of the friction coefficient of the nanocomposite and to its noticeable dependence on the content of the filler. The maximum value of the friction coefficient was also reached at 1-3 wt.% of the filler and corresponds to the greatest degree of interplanar distance in the layered silicate and to minimum microhardness and elastic modulus of the composite surface.