*4.3. Scaled-Up Composites Results*

From the lab-scale data, 30 wt.% seems the most promising HSPs amount granting both a high fiber content and acceptable mechanical properties. The results of the scaled-up composites are summarized in Table 5.


**Table 4.** DSC first heating results for H0210 and HM200 PLA-based composites.

**Table 5.** Mechanical and MFR results of the scaled-up HSPs composites.


\* Blends extruded with a semi-industrial COMAC twin-screw extruder (up-scaled).

All scaled-up formulations show a lower MFR, respect to their corresponding lab-scale formulations. This MFR decrement is also reflected in the injection pressure increment during the injection molding process (Table 2). The marked viscosity decrement observed during the lab-scale step is limited, thanks to the coupling of the low extruder residence time and the presence of the venting system connected to a vacuum pump that guarantees the humidity stripping during the melt extrusion, avoiding or limiting any eventual PLA degradation [49,50]. The mechanical results are noteworthy. In fact, it can be observed that the scaled-up composites show an increment of elastic modulus and tensile strength. In particular, the reached tensile stress is very similar, confirming the efficiency of the venting system in removing the fillers humidity.

The thermal properties (Table 6) of the scaled-up composite remains almost unchanged, confirming the nucleation effect of HSPs.


**Table 6.** DSC first heating results of scaled-up HSPs composites.

\* Blends extruded with a semi-industrial COMAC twin-screw extruder (up-scaled).
