## 3 Results and Discussion
### Thermal Analysis  
#### 3.3.1 Differential Scanning Calorimetry  
The \(\mathrm{T_{g}}\) dictates the miscibility phenomenon for polymer blends and processing conditions. As a rule, the polymer blend miscibility is associated with the observation of one single \(\mathrm{T_{g}}\)[62]. Nonetheless, a slight \(\mathrm{T_{g}}\) displacement on the PLA/PS blends suggested compatibility for those blends [42]. In other research, a single \(\mathrm{T_{g}}\) for semi-crystalline PLA/PMMA blends was reported with different PMMA compositions on the PLA matrix [63]. In addition, [PERSON] et al. [62] evaluated the miscibility of PLA/PMMA blends through two methods, as follows: (1) Solution/precipitation, and (2) solution-casting film. The results showed that for solution/precipitation, just one \(\mathrm{T_{g}}\) was observed, but two isolated \(\mathrm{T_{g}}\) were present in the solution-casting film method. Figure 5 shows the curves obtained in differential scanning calorimetry, and Figure S1 displays a zoom-in of poly(S-_co_-MMA)\(\mathrm{T_{g}}\) curves belonging to \(\mathrm{PLA_{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{  \mathrm{    }}}}}}}}}}}}}}}\) by \(\mathrm{T_{g}}\) curves belonging to \(\mathrm{PLA_{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{  \mathrm{    }}}}}}}}}}}}}}}}\) by \(\mathrm{T_{g}}\) showed a \(\mathrm{T_{g}}\) increasing behavior for both transition temperatures when compared with the polymer and random copolymer alone. These results suggest immiscibility, however, compatibility was observed in the \(E\).  
Further processing conditions (such as temperature, torque, and screw speed) for filament production are analogous to conventional extrusion. Specifically, the temperature must be between 15-60 \({}^{\circ}\)C above the \(\mathrm{T_{g}}\) or melting point for amorphous, and semi-crystalline polymers, respectively [64].  
Figure 5: Heating curves (2 nd cycle) of neat PLA, neat poly(S-_co_-MMA), and \(\mathrm{PLA_{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{ \mathrm{ \mathrm{ \mathrm{   \mathrm{   }}}}}}}}}}}}}}}}}\) by \(\mathrm{T_{g}}\) and \(\mathrm{PLA_{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{ \mathrm{   \mathrm{     \mathrm{     }}}}}}}}}}}}}}}}\) by \(\mathrm{T_{g}}\).  
Furthermore, these PLA\({}_{\text{x}}\)/poly(S-_co_-MMA)\({}_{\text{y}}\) blends have the advantage that the system is amorphous, and therefore require less energy for their transformation. The final T\({}_{\text{g}}\) of the PLA\({}_{\text{x}}\)/poly(S-_co_-MMA)\({}_{\text{y}}\) blends varied between 102.1 and 106.5 \({}^{\circ}\)C, which determined the melt blending temperature via extrusion at 195 \({}^{\circ}\)C.