## Materials and Methods
### Fast Scanning Chip Calorimetry
#### 2.3.5 Simulation of IR Thermal Profiles  
The Flash DSC 1 is only capable of imposing heating and cooling at a constant rate or isothermal temperature segments. The recorded temperature profiles from IR thermography should thus be linearly approximated for them to be simulated in the FSC device. Careful selection of data points generated sets of temperature segments with constant cooling or heating rate. For each printing condition displayed in Table 2, both the temperature profile for the 10 th layer, closer to the build plate, and the 40 th layer, farther away from the build plate, were implemented in the Flash DSC 1. As mentioned in Section 2.2, automatic calibration of the infrared camera causes data loss over a period of approximately 1 s. This data loss was compensated for in two ways. At early stages of printing, when large temperature fluctuations occurred, the lost data were replaced by previously captured data from recordings without automatic calibration. This was possible, since thermal drift inherent to the camera without automatic calibration had not yet impacted the recorded temperatures at the early stages of printing. At later stages, heating and cooling rates remained constant over longer time intervals, thus the duration of one linearized segment was much larger than the calibration time of 1 s. Therefore, the linearization was not affected by the automatic calibration. For all recorded temperature profiles, the same protocol was applied, which was comprised of a heating cycle from 25 \({}^{\circ}\)C to 250 \({}^{\circ}\)C at a rate of 100 \({}^{\circ}\)C/s. Secondly, the sample was held isothermally at 250 \({}^{\circ}\)C for 120 s to ensure the sample was completely molten. Subsequently, the sample was cooled down from 250 \({}^{\circ}\)C at the critical cooling rate of 250 \({}^{\circ}\)C/s to the first peak temperature of the simulated temperature profile. After running through the linear approximation of the temperature profile, the sample was heated again from the final temperature of the thermal profile to 250 \({}^{\circ}\)C at a rate above the critical heating rate. The resulting melting peak of this final heating step was used to assess the crystallization. One of the main advantages of using FSC to mimic the thermal history experienced by the deposited layer is the possibility to study the development of crystallinity over the course of printing. The final heating cycle was therefore not only applied at the end of the full recorded temperature profile, but also at distinct points in time during the FFF process. The temperature profiles for all printing conditions were interrupted at three points in time:  
1. after the cyclic heating and cooling at the beginning of the temperature profile, resulting from the deposition of new layers;
2. after the print finished, i.e., the last layer was deposited; and
3. at the end of the recorded temperature profile. For Conditions 1 and 6 in Table 2, the temperature profile for both the 10 th and 40 th layers were interrupted by a heating cycle after every temperature peak, resulting from the deposition of a new layer, as well as after every linear segment during cooling down of the printed part to monitor the gradual build-up of crystallinity over time in more detail. The resulting heat flow signals [J/s] were normalized by dividing by the applied heating rate [\({}^{\circ}\)C/s], since the integrated peak area differs according to the applied rate. A result was obtained in units of heat capacity [J/\({}^{\circ}\)C]. The melting peak of each signal was integrated as described in Section 2.3.3. The resulting value of the integrated peak area should then be divided by the respective sample mass of the utilized chip to compare between results obtained for HMWPA and LMWPA. Afterwards, the correction for the inherent drift due to sample changes should be applied. The obtained melting enthalpies were an explicit indication of the degree of crystallinity developed in the printed part.