## 3 Results
### Thermal Analysis (DSC)  
Differential Scanning Calorimetry (DSC) uncovers the reason for the previously described differences by an examination of their thermal properties. Figure 6 compares the DSC-runs of both polymers. Although both systems are PA12, it can be undeniably recognized from Figure 6 that they present substantially different melting and crystallization performances. The thermal transition signals show no congruence in either 1 st heating or in cooling, but only during the 2 nd heating. The exact thermal transition values (\(T_{\text{m}}\), \(T_{\text{m}}\)onset, \(T_{\text{c}}\), \(T_{\text{c}}\)onset) achieved from the DSC-runs depicted in Figure 6 and their respective enthalpies (\(\Delta H_{\text{m}}\), \(\Delta H_{\text{c}}\)), are summarized in Table 1. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**PA12 Type** & **DF-PA** & **Orgasol-IS** & **Diff. Absolute** \\ \hline
**First heating run** & & & \\ Melting point \(T_{\text{m}}\) (\({}^{\circ}\)C) & 187.0 & 182.0 & \(\Delta=5.0\)\({}^{\circ}\)C \\ Melting onset (\({}^{\circ}\)C) & 180.8 & 173.6 & \(\Delta=7.2\)\({}^{\circ}\)C \\ Melting enthalpy \(\Delta H_{\text{m}}\) (J/g) & 110.7 & 102.3 & \\
**Coaling run** & & & \\ Crystallization point \(T_{\text{c}}\) (\({}^{\circ}\)C) & 143.2 & 151.1 & \(\Delta=7.9\)\({}^{\circ}\)C \\ Crystallization onset \(T_{\text{c}}\)onset (\({}^{\circ}\)C) & 148.3 & 154.0 & \(\Delta=5.7\)\({}^{\circ}\)C \\ Crystallisation enthalpy \(\Delta H_{\text{c}}\) (J/g) & 48.0 & 56.1 & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Thermal transition points (\(T_{\text{m}}\), \(T_{\text{m}}\)onset, \(T_{\text{c}}\), \(T_{\text{c}}\)onset) and corresponding enthalpies (\(\Delta H_{\text{m}}\), \(\Delta H_{\text{c}}\)). Figure 6: Comparison of the thermal behavior of Duraform® PA (DF-PA) (blue) and Orgasol® Invent Smooth (Orgasol-IS) (red) by thermal analysis (DSC). The DSC-runs in Figure 6 and the respective thermal values in Table 1 show some distinct thermal differences between DF-PA and Orgasol-IS. The following features and findings of the thermal properties can be derived:  
* The melting point (\(T_{\rm m}\)) and melting-onset (\(T_{\rm m}\)onset) of DF-PA is 5.0 \({}^{\circ}\)C, which is 7.2 \({}^{\circ}\)C higher than for Orgasol-IS. This is a clear sign of why the part bed temperature for Orgasol-IS must be drastically lowered, as the build temperature in LS-processing is typically set close to the melting onset. * The melting enthalpy (\(\Delta H_{\rm m}\)) for both materials is over 100 J/g, and therefore, is two times higher than would be expected for standard PA12 [20] as it was found in the respective 2 nd heating runs (approx. 50 J/g-60 J/g). * The crystallization point (\(T_{\rm m}\)) and crystallization onset (\(T_{\rm m}\)onset) for DF-PA is 7.9 \({}^{\circ}\)C, which is 5.7 \({}^{\circ}\)C lower than for Orgasol-IS. * In the 2 nd heating run, all values are significantly different from their individual first heating run and show lower values, with a tendency for the lowest values for DF-PA. These findings give a clear indication that the polymer manufacturers adjust both materials for optimized LS-processing. A high melting enthalpy is induced and is beneficial for a high contour resolution of parts, as it raises the threshold for the thermal bleeding of neighboring particles. The shift in \(T_{\rm m}\) and \(T_{\rm c}\), and their respective onsets, is an adjustment to create more stable processing through the widening of the sintering window. The sintering window is calculated using Formula 2 [22]. \[\text{Sintering window (${}^{\circ}$C) = Melting onset (${}^{\circ}$C)-Crystallization onset (${}^{\circ}$C)} \tag{2}\]  
The sintering window is particularly pronounced for DF-PA with a value of 32.5 \({}^{\circ}\)C, compared to 19.6 \({}^{\circ}\)C for Orgasol-IS. A lower onset of crystallization is a key element for the desired suppression of crystallization during the slow cooling rates of the LS-process. DF-PA explicitly outperforms Orgasol-IS in this context.