Steric Repulsion of Polymethacrylate Layers 961218
The rheology of two adsorbed layers of polymethacrylate (PMA) between two carbon surfaces were investigated using a Surface Force Apparatus (SFA). Each polymer layer is obtained by adsorption in a dilute solution of PMA polymer and dispersant DPMA polymer in a 175 Neutral Solvent basestock at 25°C. The aim of these experiments is the characterization of steric behavior of the polymer films. It is found that the adsorption of pure PMA on carbon surface is low, so the steric repulsion is inefficient and that adhesion between the carbon surfaces takes place as in pure base oil. In the contrary, the adsorption of dispersant PMA on carbon surface forms a 34 nm thick protective layer, which can give an effective repulsion effect.