New Nanoindentation and Nanoscratching Parameters of Thermoplastics

• Published in: Macromolecular symposia 2008-12, Vol.274 (1), p.72-80
• Main Authors: Naimi-Jamal, M. R., Kaupp, G.
• Format: Article
• Language: English
• Subjects: Applied sciences; atomic force microscopy (AFM); chain breakage; Exact sciences and technology; Isotactic; Mechanical properties; Nanocomposites; Nanoindentation; Nanomaterials; nanoscratching; Nanostructure; Organic polymers; Physicochemistry of polymers; Properties and characterization; Quantitative analysis; Thermoplastic resins; thermoplastics; Transformations
• ISSN: 1022-1360; 1521-3900
• DOI: 10.1002/masy.200851411

The determination of hardness and modulus values from unloading curves in nanoindentations is particularly troublesome with thermoplastic polymers and the values can strongly depend on the maximal normal force. Quantitative analysis of the loading curves provides reliable nanoindentation coefficients k (µN nm−3/2) as the slopes of linear plots that reliably characterize the pristine polymers and are potent interpolation tools. Kinks in the linear plots (here not observed with isotactic polypropylene (PP‐it)) indicate plastic‐viscoelastic transformations and separate the characterization of the degraded polymer with the smaller nanoindentation coefficients from the pristine polymer. The quantitative analysis of the correct relation between lateral and normal force in nanoscratching reveals the coefficient K (µN−1/2) as a basic extrapolation tool with direct and quantitative access to scratch resistance as a measure for wear that replaces the unfounded and never constant so‐called “friction coefficient FL/FN”. The linear plots of the correct relation between lateral and normal force reveal the occurrence of plastic‐viscoelastic transformations most distinctly by a kink and two linear ranges.