Experimental Part
Three types of materials are studied in order to cover a relatively wide range of materials with different structures and properties. Samples are subjected to uniaxial deformation and the nanostructure evolution is monitored by SAXS.
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Experimental Part
“There is need of a method for finding out the truth.” …René Descartes
2.1 SAXS Setup Three types of materials are studied in order to cover a relatively wide range of materials with different structures and properties. Samples are subjected to uniaxial deformation and the nanostructure evolution is monitored by SAXS. Figure 2.1 presents schematically the experimental setup. Small-angle X-ray scattering (SAXS) is carried out at the synchrotron beamline A2 at HASYLAB, Hamburg, Germany. The X-ray path is perpendicular to the sample. The sample-detector distance for a SAXS study is generally about 2000–3100 mm. The wavelength of radiation is 0.15 nm. Scattering intensity is collected by a 2D marccd 165 detector (Marresearch, Norderstedt, Germany) in binned 1024×1024 pixel mode (pixel size: 158.2 µm × 158.2 µm). Thus for the typical long period of 20 nm a variation of the peak position by one pixel causes a long period variation of below 1 %. The intensities of the primary beam before the sample and of the transmitted beam after the sample are recorded in order to calculate the absorption factor of the material. Tensile testing is done in a home-made [1] stretching-machine. The machine performs symmetric drawing in order to maintain the position of the beam on the sample. Signals from load cell and transducer are recorded during the experiment. The macroscopic deformation is determined close to the beam position to ensure accurate comparison of the mechanical data with the nanostructure evolution. For this reason a precise method has been developed [2]. In this method a pattern of fiducial marks is stamped on the sample. The sample is monitored by a TV-camera. Using the fiducial marks the local strain ε = ( − 0 )/0 is computed automatically
A. Zeinolebadi, In-situ Small-Angle X-ray Scattering Investigation of Transient Nanostructure of Multi-phase Polymer Materials Under Mechanical Deformation, Springer Theses, DOI: 10.1007/978-3-642-35413-7_2, © Springer-Verlag Berlin Heidelberg 2013
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2 Experimental Part
Fig. 2.1 Schematic presentation of the experimental setup used for in-situ SAXS measurements during mechanical deformation. The original drawing has been provided by Courtesy of C. Schloen
from the average initial distance, 0 , of the fiducial marks and the respective actual distance, . More details will be presented in Chap. 3. Details about the sample preparation and experimental conditions of each group of the studied materials are presented in the following three sections.
2.2 Thermoplastic Polyurethane Elastomers Material. A thermoplastic polyurethane (TPU) is injection molded from melts of different temperature. The material is a commercial grade polyester based thermoplastic polyurethane (TPU) with 94 Shore A durometer hardness from Huntsman Inc., e.g. for sealing applications. The TPU has been polymerized in a one-step process and is provided in granular form ground from cast film. Injection molding.1 Samples for the SAXS measurements have been processed directly from the
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