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Molecular characterization of polymers
Plastic materials mainly consist of polymers (macromolecules) and a set of additives, which modify, influence, and retain the end-use properties of the plastics.
The mechanical useful properties (e.g. tensile strength, hardness, modulus, impact strength) are mainly influenced by the composition and phase structure of the polymers. Therefore, an understanding of the structure-property relationship is necessary for the development of new polymers with defined characteristics.
At the Chair of Polymeric Materials numerous techniques are available which allow detailed characterization of polymers, e.g. according to their molar mass distribution, comonomer content, and degree of short-chain or long-chain branching:
- Room- and High Temperature Size Exclusion Chromatography (SEC);
- Analytical and preparative fractionation techniques, such as Temperature Rising Elution Fractionation (TREF), Crystallization Analysis Fractionation (CRYSTAF), and Holtrup Fractionation.
The experimental equipment also includes a coupling of high performance liquid chromatography with mass spectrometry (HPLC/MS-coupling) to analyse additives as well as their decomposition products in plastic materials.
Especially for low molar mass components the 400 MHz NMR-spectrometer is another important and powerful tool for a precise molecular characterization.
The research area of Molecular Characterization also includes the development and refinement of analytical methods with statistical models which help to understand phase separation and phase transistion of polymers. The results achieved hereof can be eventually applied to optimize the experimental conditions during analyses.