## 3 Results
### Mechanical Properties and Anisotropy  
The mechanical properties summarized in Table 2 were achieved by the investigation of parts described in Section 2. All parts were produced and randomly distributed in the LS build chamber of the said DTM machine per Figure 3, with the build parameters given in Figure 5. In order to have a better overview of the data for the present study (the data rows are named \"present work\" in Table 2), the results are compared with data from the powder producers presented in their respective \"Material Data Sheet (MDS)\".  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Value**} & \multirow{2}{*}{**Unit**} & \multicolumn{3}{c}{**Duraform® PA**} & \multicolumn{3}{c}{**Orgasol® Invent Smooth**} \\ \cline{3-8}  & & \multicolumn{2}{c}{**MDS ***} & \multicolumn{2}{c}{**Present Work**} & \multicolumn{2}{c}{**MDS ***} & \multicolumn{2}{c}{**Present Work**} \\ \hline build direction & & XYZ & XYZ & ZXY & XYZ & XYZ & ZXY \\ \hline Young’s modulus & & & & & & & \\ ISO-527-1 & & & & & & & \\ \hline Tensile strength & & & & & & & \\ ISO-527-1 & & & & & & & \\ \hline Elongation at break & & & & & & & \\ ISO-527-1 & & & & & & & \\ \hline Charpy un-notched & & & & & & & \\ ISO 197 TeV & kJ/m\({}^{2}\) & - & & & & & \\ \hline Charpy notched & & & & & & & \\ ISO 197 1 eA & & & & & & & \\ \hline \hline \end{tabular}  
* MDS = material data sheets of powder producers.  
\end{table}
Table 2: Results of the tensile and impact tests for Duraform®PA (DF-PA) and Orgasol®Invent Smooth (Orgasol-IS) in different orientations and compared with data from the Material Data Sheet (MDS) * of powder suppliers.  
Figure 8: Comparison of volume distribution of DF-PA and Orgasol-IS by laser diffraction.  
The following comments and conclusions can be derived from Table 2:  
* The XYZ-orientation of the values of this work match relatively well with the MDS values for Young's modulus and tensile strength. This can be expected, as these values are material inherent to a great extent.
* For Elongation at the break in the XYZ-direction, only about half of the published value was achieved. This could be due to applying high-resolution build parameters for this study. Published mechanical data will be achieved most likely with property optimized build settings.
* For the Charpy measurements, there is only one MDS value published: 34 kJ/m\({}^{2}\) for un-notched Orgasol-IS. As this value is consistent with this study's measured value, it is assumed that all Charpy data for the XYZ-direction also lie in the expected range.  
So, for the XYZ-direction, all measured values are truthful compared to MDS-data. In order to reveal the anisotropy of the parts, an analysis for the XYZ- and ZXY-direction data leads to the following statements:  
* For tensile strength, DF-PA remains at nearly the same level, while Orgasol-IS drops to almost half the value.
* For Elongation at the break, the drop for DF-PA is about 50%, whilst Orgasol-IS loses 85% of the initial magnitude.
* Finally, in the case of the Charpy tests (un-notched and notched) for Orgasol-IS, the loss of stability in the ZXY-direction is drastic in comparison to DF-PA.  
In summary, this means that Orgasol-IS is much more affected by anisotropic mechanical properties than DF-PA.  
As LS is a layer-by-layer technology, the weak point in the microstructure of the parts is the boundary between the layers. Based on the mechanical test results, this means that layer adhesion for Orgasol-IS is largely reduced. A sufficient isotropy during the sintering process can be achieved by a good interconnection of the polymer melt at the layer interface, through sufficient polymer chain entanglement. These diffusion-driven effects are correlated with the polymer melt viscosity.