## 3 Results and Discussion
### Thermomechanical Stability  
Measurement of the T\({}_{\text{g}}\) is a criterion used to determine the phase behavior of a polymer blend. The main change for PPE/HIPS/SBS blends occurs in soft phase glass transition temperature (T\({}_{\text{gSP}}\)) and rigid phase glass transition temperature (T\({}_{\text{gRP}}\)) due to phase rich of PB (HIPS + SBS) and phase rich of PS/PPE (SBS, HIPS and PPE), respectively [38; 47; 48]. It is well known that three phases are identified for SBS block copolymers: PB in the pure PB phase (T\({}_{\text{g1}}\)), PB in the mixed PB-PS phase rich in PB (T\({}_{\text{g2}}\)), and PS only present in a mixed PB-PS phase rich in PS (T\({}_{\text{g3}}\)) [49; 50]. Figure 6a displays the T\({}_{\text{gSP}}\) of the PPE/HIPS/SBS411R-TSE, PPE/HIPS/SBS416R-TSE, and PPE/HIPS/SBS4301L-TSE blends. Compared with PPE/HIPS-22-TSE, the PPE/HIPS/SBS411R-TSE and PPE/HIPS/SBS416R-TSE blends show lower values. Meanwhile, the PPE/HIPS/SBS4301L-TSE blend exhibits superior values except for the PPE/HIPS/SBS4301L-24-TSE blend. Figure 6b illustrates the T\({}_{\text{gSP}}\) of the PPE/HIPS/SBS411R-IM, PPE/HIPS/SBS416R-IM, and PPE/HIPS/SBS4301L-IM blends. The PPE/HIPS/SBS411R-IM, PPE/HIPS/SBS4301L-IM, and PPE/HIPS/SBS416R-IM blends diminished their T\({}_{\text{gSP}}\) than the T\({}_{\text{gSP}}\) of PPE/HIPS-22-IM, forming a PB-PS phase more abundant in PB. In contrast, the PPE/HIPS/SBS4301L-6-IM blend exhibited a higher T\({}_{\text{gSP}}\) than the PPE/HIPS-22-IM. Therefore, the soft domains formed in the PPE/HIPS/S416R-IM and PPE/HIPS/S4301-IM blends could be due to the PB-PS phase richest in PB and the poorest in PB (or abundant in PS), respectively, Figure 6b. Note that in PPE/HIPS/SBS416R-24-IM, a substantial reduction in the T\({}_{\text{gSP}}\) occurred, suggesting a diminished PS content in the rubbery block and, therefore, a soft phase richer in PB than present in PPEHIPS-40%-IM and PPE/S416R-40%-IM, see Figure 6c. Furthermore, PPE/S416R-40%-IM contains 12 wt% of PS, making PPE only a little miscible with SBS. Due to PB and PPE were not miscible at the higher PB content, this will cause a significant phase separation [32]. Consequently, the blocks of PS and PB will interact, and a more considerable amount of PS will be present in the rubbery block, promoting the shift of T\({}_{\text{gSP}}\) to a higher temperature [42; 51]. Figure 5: Han plots of PPE/HIPS/SBSX-Y-Z blends: (**a**) PPE/HIPS/SBS411R-Y-TSE; (**b**) PPE/HIPS/SBS416R-Y-TSE; (**c**) PPE/HIPS/SBS4301L-Y-TSE; (**d**) PPE/HIPS/SBS411R-Y-IM; (**e**) PPE/HIPS/SBS416R-Y-IM; (**f**) PPE/HIPS/SBS4301L-Y-IM. Regarding T\({}_{\text{gRP}}\), which corresponds to the T\({}_{\text{g}}\) of the PPE-PS rigid phase. In addition, the T\({}_{\text{g}}\) shift depends on the component interactions, i.e., PPE and PS with the rubbery block [47,48,52]. Hence, the PB content significantly affects the shift of T\({}_{\text{g}}\) PS, suggesting an additional interaction between the PS phase, from HIPS or SBS, with the phase of PB [10,53,54]. As SBS content increases, the T\({}_{\text{gRP}}\) is shifted towards lower temperatures concerning the T\({}_{\text{gRP}}\) of P/H-22%, regardless of the processing method (IM or TSE), see Figure 6d,e. However, a reduced content of PPE led to a reduction of the T\({}_{\text{g}}\) of the PPE-PS T\({}_{\text{gRP}}\). It is important to note the incorporation of PS into the PPE. The T\({}_{\text{gRP}}\) of PPE/HIPS/SBS4301L-TSE blends exhibits lower values than the PPE/HIPS/SBS411R-TSE and PPE/HIPS/SBS416R-TSE blends (both with radial architecture), see Figure 6d. A similar behavior is observed for mixtures processed by IM, see Figure 6e. This finding can be explained by the fact that S4301L has significant PS content and moderate viscosity. Therefore, the incorporation of the PB from S4301L into the PPE is more favorable than for the other SBS416R and SBS411R copolymers, regardless of the processing method.