Fracture Mechanics Properties of Polymorphic Polypropylene

Abstract

Polypropylene (PP) is a widely used thermoplastic and polymorphic polymer. Three different types of PP were prepared, namely non-nucleated, -and -nucleated PP. These materials were pressed using different cooling rates to influence the degree of crystallinity within the materials, which was determined by differential scanning calorimetry (DSC). The materials resistance against stable crack propagation was described by R-curves. The J d -a curves were determined using the instrumented Charpy impact test (ICIT) to apply single edge notch bending specimens (SENB) with a high loading velocity. The results show not only the influence of the cooling rate on the degree of crystallinity but also a correlation between the degree of crystallinity and the materials resistance against stable crack propagation. The lower the cooling rate of the material is the higher is the degree of crystallinity and the higher seems to be the materials resistance against stable crack propagation.

Investigating the Morphological Variations Due to Processing and Thermomechanical Treatment of Poly(propylene) Using Raman Microscopy

“…The latter embody themselves in the form of spatial variations in morphology, with their length scale and variance depending on the specific process and conditions. These in turn have a significant impact on the macroscopic properties, such as mechanical properties and crack propagation . Hence, spatially mapping the morphology in a comprehensive manner is an important task in order to establish process→structure→property relationships and use these to optimize manufacturing …”

“…These in turn have a signifi cant impact on the macroscopic properties, such as mechanical properties and crack propagation. [3][4][5] Hence, spatially mapping the morphology in a comprehensive manner is an important task in order to establish process→structure→property relationships and use these to optimize manufacturing. [ 6 ] The morphology of PP has been well studied and it has been known that PP crystallizes in three different polymorphs, namely, the α-, β-and γ-form.…”