The thermal histories of polyimide films were varied to study the effect of the extent of imidization on the response of films to rubbing. Films rubbed prior to imidization formed tears that extended to the substrate; tears in these films formed at smaller film thicknesses than in films imidized prior to rubbing. Aligned nanoscopic islands were also seen. The alignment of these islands disappeared upon imidization. Films imidized at a low temperature showed less alignment of islands than conventionally prepared films. (C) 2004 Wiley Periodicals, Inc.