A new type of fracture induced structuring (FIS), which shows concentric semi-circular wrinkles with periodic spatial wavelength. A complementary set of nonsymmetrical concentric surface wrinkling of polymer is formed on the fractured surface of a polymer thin film which is sandwiched between two rigid plates. We examined several parameters such as thickness of polymer film, kind of polymer, substrate thickness and separating rate of the sandwich structure to affect fracture induced structure. The effect of material properties of polymer thin films on the surface modulation of FIS is also studied using gamma-irradiation.
The ring-type surface wrinkling of the polymeric films is considered to be generated by the presence of the compressive residual surface stress which can be described by the apparent surface traction. The polymer resist (mr-8030E) and polystyrene were used to investigate the phenomenon of ring-type surface wrinkling. Using the spatial wavelength of the surface wrinkling and the initial film thickness of polymer thin film, the apparent surface traction which is a combination of surface energy and residual surface stress was found as a function of the film thickness. The magnitude of the apparent surface stress decreased with decreasing film thickness and approached a constant value.

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