Corresponding topography (a) and phase (b) images of 15 ?m x 15 ?m area of polypropylene (PP) matrix within a commercial impact copolymer (ICP) material at 2% elongation. Regions of large crack formation are highlighted in orange and blue circles. Zoom in on crack highlighted in orange circle in (a) is shown in corresponding topography (c) and phase (d) images. Line scan in (c) along red line measures width and depth of crack. Imaged with the MFP-3D AFM and NanoRack accessory.