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T. Koch, F.R. Kogler, U. Schubert, S. Seidler:
"Characterization of Organic-Inorganic Hybrid Materials by Indentation Techniques";
Talk: Polymerwerkstoffe 2006, Martin-Luther-Universität, Halle-Wittenberg, Deutschland; 09-27-2006 - 09-29-2006; in: "Polymerwerkstoffe 2006", (2006), 29.

Organic-inorganic hybrid materials were prepared by a step-wise free radical co-polymerization of styrene and the multifunctional zirconium oxo cluster Zr₆O₄(OH)₄(methacrylate)₁₂ (Zr6). The .concentration of the cluster in the polymer matrix was varied. Neat polystyrene was also prepared for comparison.
With the help of (micro)indentation and scratch testing, the inftuence of the Zr6 clusters on the mechanical properties such as hardness, stiffness. creep, craze initiation and scratch resistance were shown.
There was only a slight increase in hardness and in indentation modulus with higher cluster loadings. This observation was in agreement with the compression behaviour of the materials.
Whereas the tensile properties showed a much stronger dependence on the Zr6 content.
With increasing cluster content, an increase of craze initiation stress. as determined by ball intentation experiments, was found.
Performing scratch testing with constant load, a reduction of pile-up and a stronger recovery were observed for the hybrid materials. Scratch tests with a constant increase of load showed an increase of the critical load for crack openmg dunng scratching, which is an important material parameter for predicting the wear resistance.