Microstructure-Related Scratch Resistance and Indentation Creep Behavior of PA6 and PA6 Nanocomposites

Instrumented scratch test was carried out to determine the scratch resistance of polyamide 6 (PA 6) nanocomposites, where two kinds of nanofillers were tested, both based on silicates: montmorillonite (MMT) and halloysite nanotubes (HNT). In this work the influence of the sliding velocity, normal applied load and time-dependent recovery on the penetration depth and scratch hardness was investigated. Optical microscopy was utilized to determine the width of the scratch grooves and scanning electron microscopy revealed the damage features of the scratched surfaces. Both MNT and HNT nanofillers improve the scratch resistance of PA 6 considerably. As a result of the microstructure of the polymer nanocomposites MNT gives PA 6 a better residual depth resistance while HNT raises its scratch hardness (i.e. reduces the scratch width). Furthermore, via different depth-sensing indentation techniques in the nano-, micro- and macro-range of loading the short-term performance (Martens hardness and indentation modulus) and the time-dependent creep behavior have been analyzed for PA 6 and the PA 6 nanocomposites as a function of applied load and temperature. Additionally, WAXS (wide-angle X-ray scattering) and DSC (differential scanning calorimetry) measurements to establish morphology–property relationships of the materials investigated considering the skin–core structure of the injection molded samples were made.