# Towards Self-Reinforced PLA Composites for Fused Filament Fabrication
## 3 Methods  
### Processing and Optimising the PLA Composite Filament for the FFF 3D printer  
Herein, the fabrication of matrix material A and matrix material B from pellets to filament is described. The matrix material A was PLA Luminy L130, which was selected to process the Sc-PLA fibre. The matrix material B was PLA Ingeo 6302D, corresponding to the bi-co PLA fibre.  
Production set-up: the work-flow of the filament production was established on an assembly of units as shown in Figure 5 and the schematic figure of the extrusion line for the production of the filament is shown in Figure 6. The heart of the set-up was the polymer extruder machine from Axon AB plastic machinery [51]. The matrix pellets were fed into the hopper (station 1), from where the pellets moved into the screw (station 3), changing the solid to viscoelastic. For the production of the future continuous fibre reinforced filament, we used the self-fabricated nozzle suiting the production capacity of the extruder as shown in Figure 7 (station 2). The molten polymer exited the nozzle. From the nozzle, the filament was drawn into a water-bath path (station 4), providing uniform cooling. The solidified filament passed to the conveyor belt (station 5), accessorsied with a roller on top. For controlling, the filament passed a laser diameter controller (station 6) and wound up on the spool-winding station (station 7). The matrix A pellets PLA Luminy L130 were pre-dried in a vacuum oven at 60 \({}^{\circ}\)C. Luminy L130 has a T\({}_{g}\) of 60 \({}^{\circ}\)C and a T\({}_{m}\) of 175 \({}^{\circ}\)C. Table 6 presents the processing temperatures \(T\) at the extrusion machine for matrix material A, Luminy L130.  
Figure 4: (**a**) visualisation showing core PLA and matrix PLA for the Sc-PLA PLA composite, (**b**) visualisation showing core bi-co fibre in the PLA matrix for the second self-reinforced composite, and (**c**) cross section of the bi-co fibre showing the inner core and the outer sheath material construction. The mechanical properties are mentioned in Tables 2, 3 and 5.  
The matrix B pellets PLA Ingeo 6302D were pre-dried at 40 \({}^{\circ}\)C. Ingeo 6302D has a T\({}_{\rm g}\) between 55 \({}^{\circ}\)C and 65 \({}^{\circ}\)C and a T\({}_{\rm m}\) between 125 \({}^{\circ}\)C and 135 \({}^{\circ}\)C. Ingeo 6302D was fabricated at the following processing temperatures at the extrusion machine. The optimisation of the filament during the extrusion production is explained in detail in Section 3.2  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Extrusion Zone** & **Temperature** \\ \hline
1 & 130 \({}^{\circ}\)C \\
2 & 175 \({}^{\circ}\)C \\
3 & 176 \({}^{\circ}\)C \\
4 & 170 \({}^{\circ}\)C \\
5 & 170 \({}^{\circ}\)C \\
6 & 180 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table}
Table 6: Extrusion temperature profile for the extruder-screw. The entire screw is temperature controlled in each segment/zone separately. The matrix material A, PLA Luminy L130. Luminy L130 has T\({}_{\rm g}\) 60 \({}^{\circ}\)C and T\({}_{\rm m}\) 175 \({}^{\circ}\)C.  
Figure 5: Extrusion set-up assembly constituting the production of (un)reinforced PLA filaments. (1) Hopper, (2) nozzle for the potential reinforced filament production, (3) processing screw with 3 sections (feeding, compression and metering), (4) water bath, (5) conveyor belt, (6) laser diameter controller, (7) filament winding station.  
Figure 6: Schematic diagram of the filament production: Extrusion set-up assembly constituting the production of (un)reinforced PLA filaments. (1) Hopper, (2) nozzle for the potential reinforced filament production, (3) processing screw with 3 sections (feeding, compression and metering), (4) water bath, (5) conveyor belt, (6) laser diameter controller, (7) filament winding station.