Nucleation of branches in elastomeric polypropylene

Subsurface Imaging of Soft Polymeric Materials with Nanoscale Resolution

“…The second system is a thin film of elastomeric polypropylene . Its surface properties and volume structure have been studied previously. ,− We investigated a 250 × 250 nm 2 surface area by recording 50 × 50 APD curves with 5-nm separation. From these data, we have reconstructed maps of k TS as a function of depth z and combined them into a volume image.…”

Surface versus Volume Properties on the Nanoscale: Elastomeric Polypropylene

“…The relationship between the macroscopic mechanical behavior and the internal mechanical processes and structure (elastic and inelastic deformation, fracture, etc.) on the micro- and nanometer scale is still a topic of debate. ,− Systematic design of customized polymeric materials relies on structural and nanomechanical characterization techniques. ,, Most techniques that are used to measure structural and mechanical properties on the nanoscale rely on the atomic force microscope (AFM) − and usually extract mechanical properties, such as the elasticity from force-versus-distance measurements. , Single force-versus-distance measurements, however, provide only point information at a predefined position and hence are not sufficiently dimensioned to understand the correlation between the structural inhomogeneity and the spatial distribution of elasticity or adhesion …”

“…For full property mapping, various advanced AFM techniques have been proposed to simultaneously acquire the surface topography and maps of the nanomechanical properties of polymeric materials, ,,− but atomic force microscopy measurements are inherently restricted to the surface. Thus, the volume must be inspected in a layer-by-layer manner to obtain the structural and mechanical information within the bulk of a sample. ,− This nanotomographic information is of particular interest for semicrystalline polymers because not only the nanomechanical properties but also the number, shape, and spatial arrangement of the crystalline component contribute to the macroscopic elasticity and the material strength. ,,,, Other central aspects that influence the large scale material properties are inhomogeneities in the crystallinity (i.e., general density fluctuations), growth of spherulites, , and large-scale differences in the composition and structure caused by liquid–liquid phase separation during the crystallization process. − Additionally, modeling approaches used to predict the viscoelastic behavior of semicrystalline polymers crucially rely on structural information and the nanomechanical properties of the different phases within the material, which are used for model parametrization and validation. ,, In this work, we use the peak-force tapping mode to correlate the morphology of elastomeric polypropylene (ePP) with quantitative mechanical properties, such as elasticity, adhesion, and dissipation. Successive etching provides these physical properties for the layers located beneath the surface.…”