The brittleductile 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-phenyleneoxide) films has been studied as a function of annealing temperature. The surfacetopography of these films was studied by scanning probe microscopy following asingle sliding pass. Casting from toluene results in a semicrystalline film with a rigidamorphous phase and containing a small amount of residual solvent that exhibits ahigher interfacial shear stress than a high temperature annealed solvent-free amorphousfilm. Films containing small amounts of toluene exhibit a wear pattern consistingof ripples oriented perpendicular to the sliding direction following a singlesliding pass. These results support the notion that the interfacial shear stress is afunction of the shear yield stress, and, that during sliding friction tensile stressesmust form at the polymer surface.