In situ microscopic surface characterization studies of polymeric thin films during tensile deformation using atomic force microscopy

Atomic force microscopy (AFM) has been used to study the cracks developed o n thin-film coatings on a polymer substrate subjected to external tension. To conduct in situ tensile tests in AFM, a special stage has been built. A new technique to image the same control area at different strains was devel oped and used to study the propagation of a crack with increasing strain in magnetic tapes. Metal particulate tapes developed numerous cracks of short er length, perpendicular to the loading direction. In contrast, metal-evapo rated tapes developed cracks that extend edge to edge. The variation of the crack width and the spacing with strain were measured and explained with t he help of models based on elasticity.