## 3 Results and Discussion
### Simulation of Thermal Profiles Using FSC
#### 3.2.4 Approximation of Thermal Profiles and Simulation in FSC  
To be able to exploit the recorded thermal profiles in the FSC device, the temperature versus time curves should be approximated by linear segments of constant heating or cooling rate. An example of such a linear approximation is depicted in Figure 7 for Condition 2 with markings for the end of each zone in the thermal history. At these points in time, for all analyzed print conditions, the samples were remelted to assess the thus far developed crystallinity through integration of the resulting melting peaks. \begin{table}
\begin{tabular}{c c} \hline
**Valid for Condition(s):** & **Correction Factor** \\ \hline
1 \& 4 & \(1\cdot 10^{-7}\) \\
2, 3 \& 5 & \(-4\cdot 10^{-8}\) \\
6 & \(7\cdot 10^{-8}\) \\ \hline \end{tabular}
\end{table} 
Table 4: The correction factors for drift due to sample changes for the analyzed print conditions. Figure 6: The melting enthalpies from isothermal crystallization measurements during FSC measurements of thermal profiles corresponding to Conditions 2, 3 and 5 with linear fit. Figure 8a shows a more detailed view of the linear approximation imposed onto the thermal profile for Layer 10 of Condition 1. Here, the data loss accompanying the automatic calibration of the IR camera is clearly visible as segments with constant temperature. The linear approximation cuts off these segments, since the period of data loss is smaller than the actual approximated segment of the temperature curve. The peaks of the temperature profile, coinciding with successive deposition of new, hot layers, reveal a dual peak. This dual peak consists of a superposition of a sharp initial peak, attributed to the reflection by the nozzle of the print head, and a second peak with more gradual cooling corresponding to the actual deposition of a new layer. Since no IR intensity values can be accessed through the IR camera software, no correction for the nozzle reflection can be applied on the recorded IR profile as was previously reported in literature [35]. For Conditions 1 and 6, two approximations of their thermal profiles were analyzed to examine the effect of using the corrected linear approximation: one for which the full profile was approximated and one for which correction for the nozzle reflection was applied, shortcutting the first sharp peak, as illustrated in Figure 8b. Figure 8: **(a)** A zoomed in view of the linear approximation of the thermal profile, in this case for Layer 10 of Condition 1. **(b)** An example of linear approximation with correction for the peaks associated with reflection from the print head. Figure 7: The linear approximation of the temperature profiles for Condition 2 with markings for the end of each zone. The melting enthalpies produced by remelting the FSC samples after each zone in the respective thermal profiles using a full linear approximation without any correction for nozzle reflection are summarized on Figure 9 for all printing conditions. \"Low\" and \"High\" refer to the 10 th and 40 th layers, respectively. A clear increase in melting enthalpy can be observed over the course of printing corresponding to a growing degree of crystallinity of a deposited layer over time. A significant portion of the obtained degree of crystallinity is already acquired during the first zone of cyclic heating and cooling, marking the importance of these cyclic annealing cycles for the development of part crystallinity. For most conditions, the 10 th layers exhibit a stronger increase in melting enthalpy over the second zone compared to the 40 th layers, as for the latter the second zone is much shorter. When comparing the different conditions using HMWPA, it can be observed that the build plate temperature has a significant impact on the degree of crystallinity that can be obtained during printing.