Multiscale mechanical characterization of iPP injection molded samples

Micromechanical Characterization of Complex Polypropylene Morphologies by HarmoniX AFM

“…Since the chemical etching is effective in removing the softer contribution due to the cutting procedure and HarmoniX AFM gives the mechanical properties of the material beneath the tip, HarmoniX AFM measurements are able to assess the effect of the injection molding process conditions on the mechanical characteristics of the final object [28,30]. Furthermore, with 12 h etching time, the topographic image is significantly improved.…”

“…Under these solidification conditions, high level of molecular orientation is frozen to form well ordinated and confined fibrillary crystals [62]. As highlighted in the topographies of Figure 5(a), the structures detected along the sample thickness, that is, the spherulites and the fibrils, have different organization and different orientations, and thus the elastic modulus could be expected to be influenced also by the molecular arrangement [28]. Figures 5(b) and 5(c) show maps of the peak force and adhesion force recorded in the same areas.…”

“…A rectangular cavity having a length of 110 mm, a width of 12.7 mm, and a thickness of 1.5 mm was employed. Supplementary information about the cavity geometry is reported elsewhere [28,38].…”

“…However, its applicability is strictly limited by the probe dimension that allows spatial resolution of the order of tens of microns and does not allow the reconstruction of an accurate mapping of the sample surface. Furthermore, the measurement of mechanical properties by this technique is time-consuming, since the largest part of measurement time is devoted to the approach of the sample surface [28]. More recently, Atomic Force Microscopy (AFM) based techniques (HarmoniX and Peak Force) have been proposed to evaluate both qualitative and quantitative nanometric-resolved maps of the mechanical properties.…”

“…In this paper, we intend to demonstrate the applicability of HarmoniX AFM technique to the characterization of molded polymer samples with complex, nonuniform morphologies [37][38][39][40][41][42], which could influence the mechanical properties of the final object [28,43,44]. To accomplish this objective, a series of HarmoniX tests have been performed on selected polypropylene molded samples.…”