The brittle–ductile transition induced by thermal ageing of toluene cast poly(2,6‐dimethyl‐1,4‐phenylene oxide) as observed by interfacial friction

The interfacial shear stress of toluene cast poly(2,6‐dimethyl‐1,4‐phenylene oxide) films has been studied as a function of annealing temperature. The surface topography of these films was studied by scanning probe microscopy following a single sliding pass. Casting from toluene results in a semicrystalline film with a rigid amorphous phase and containing a small amount of residual solvent that exhibits a higher interfacial shear stress than a high temperature annealed solvent‐free amorphous film. Films containing small amounts of toluene exhibit a wear pattern consisting of ripples oriented perpendicular to the sliding direction following a single sliding pass. These results support the notion that the interfacial shear stress is a function of the shear yield stress, and, that during sliding friction tensile stresses must form at the polymer surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1637–1643, 2009