## 3 Results and Discussion
### Thermomechanical Stability
Comparing PPE/HIPS/SBS411R prepared by both methods, it is evident that the blends compounded by TSE presented lower T\({}_{\text{gRP}}\). That indicated that a PB-PS soft domain, plentiful in PB, was formed by TSE, and a high concentration of PS into the PPE was  
Figure 6: Soft phase glass transition temperature (TgSP) (**a–c**) and rigid phase glass transition temperature (TgRP) (**d–f**) of PPE/HIPS/SBSX-Y-Z blends (**a**) PPE/HIPS/SBS411R-Y-TSE, PPE/HIPS/SBS416R-Y-TSE, and PPE/HIPS/SBS4301L-Y-TSE; (**b**) PPE/HIPS/SBS411R-Y-IM, PPE/HIPS/SBS416R-Y-IM, and PPE/HIPS/SBS4301L-Y-IM; (**c**) PPE/HIPS-40%-IM, PPE/SBS416R-24%-IM, and PPE/SBS416R-40%-IM; (**d**) PPE/HIPS/SBS411R-Y-TSE, PPE/HIPS/SBS416R-Y-TSE, and PPE/HIPS/SBS4301L-Y-TSE; (**e**) PPE/HIPS/SBS411R-Y-IM, PPE/HIPS/SBS416R-Y-IM, and PPE/HIPS/SBS4301L-Y-IM; (**f**) PPE/HIPS-40%-IM, PPE/SBS416R-24%-IM, and PPE/SBS416R-40%-IM. achieved. Figure 67 compares the T\({}_{\text{gRP}}\) of PPE/HIPS-40%, PPE/SBS416R-40% concerning PPE/HIPS/SBS416R-24%. Note that as the SBS content increased, the T\({}_{\text{gRP}}\) rose; thus, there was a lesser amount of PS in the blend, and consequently, a hard phase poorer in PS promoted the shift of the T\({}_{\text{gRP}}\) to higher temperatures. Regarding thermomechanical stability, the storage modulus (E\({}^{\prime}\)) of all PPE/HIPS/SBS blends, depending on SBS content and type of processing, reveals higher E\({}^{\prime}\) for TSE in comparison to IM at 25 \({}^{\circ}\)C, see Figure 7a,b [55; 56; 57]. When SBS content increases for the PPE/HIPS/SBS blends, E\({}^{\prime}\) decreases for both methods. However, a significant loss of E\({}^{\prime}\) occurs at the first concentrations, suggesting that a loss of stiffness does not accompany an increase in SBS above 12 wt%. This behavior was related to a higher number of physical cross-linking sites in radial copolymers than in linear copolymers, which triggered enhanced mechanical properties in the PPE/HIPS/SBS with radial copolymers than in those with linear blocks [32; 33; 34]. For this reason, the PPE/HIPS/SBS4301L-TSE blends exhibited higher E\({}^{\prime}\) and T\({}_{\text{gSP}}\), suggesting that the dissolution of the microdomains of the PS blocks in PB was significant. Therefore, lesser incorporation of the PS blocks in the PPE phase occurred concerning the other blends [56]. The E\({}^{\prime}\) at 0 wt% SBS (corresponding to PPE/HIPS-22 and regardless of the processing method) was the highest, as expected since the stiffness reduction upon the incorporation of a soft block in a hard phase has been extensively reported (Figure 7a,b). Figure 7c illustrates the E\({}^{\prime}\) of the blends with 60 wt% PPE processed by IM. Because all blends showed similar behavior, only the comparison of E\({}^{\prime}\) of PPE/HIPS/SBS416R-IM  
60/40-X/X blends is illustrated. As observed, for the S416R increment from 0 to 40 wt%, the contents of PS and PB diminished and raised, respectively. Thus, for lesser incorporations of the PS blocks in the PPE phase, the stiffness of the rigid domain increased since PS has a lower stiffness than PPE, causing the increment in E\({}^{\prime}\). Comparing processing methods, Figure 7d, E\({}^{\prime}\) of PPE/HIPS/SBS411R-12, by TSE and IM, was 1.47 GPa and 1.20 GPa, respectively. In contrast, E\({}^{\prime}\) of PPE/HIPS-22, processed by TSE and IM, was 1.78 GPa and 1.74 GPa, respectively. These findings suggest that the TSE causes an improved distribution of components in the blend matrix [4,30]. In addition, the higher E\({}^{\prime}\) might be related to the lower interfacial tensions between phases and, accordingly, with enhanced interfacial adhesion. With a major dispersive action compared to the IM, the TSE intensifies the breakage of the PB domain, improving its dispersion and suppressing the coalescence in the melt, which improves the mechanical properties [12,58].