## 4 Conclusions  
In this study, PPE/HIPS/SBS blends were prepared, investigating the processed method (twin-screw extrusion (TSE) and internal mixing (IM)), the composition of SBS and its type (radial architecture, e.g., 416 and 411, and linear, e.g., 4301). For the PPE/HIPS/SBS blends, the extent of interaction between components was decisive for miscibility (HIPS:SBS) and rheological, thermo-mechanical, and impact resistance performance. The extent of interaction depended not only on the SBS architecture and content in the blend, but also on the processing method. Furthermore, an increment in the SBS content led to an enhancement in blend elasticity and impact resistance. The larger number of physical cross-linking sites in the radial copolymer chains than in the linear triblock triggered improved mechanical properties in the PPE/HIPS/SBS blends. The substantial impact resistance of the PPE/HIPS/SBS suggested a HIPS-SBS synergistic effect, which made the toughening of PPE possible. For the blends prepared with PPE in excess, significant impact resistance was achieved for PPE/HIPS/SBS411R-18-TSE, with radial architecture and the highest molecular weight (M\({}_{w}\)). Likewise, a certain amount of PS in the mixture restricts the increase in immiscibility between PPE and SBS and allows SBS to behave as an excellent toughener. The influence of the PB:PS ratio was also analyzed since  
Figure 9: Effect of PPE/HIPS/SBS ratio on the Izod impact resistance. (**a**) PPE/HIPS/SBS411R-18-TSE, PPE/HIPS/SBS411R-24-TSE against PPE/HIPS/SBS411R-TSE (1:1:1) blends; (**b**) PPE/HIPS/SBS416R-18-TSE, PPE/HIPS/SBS416R-24-TSE against PPE/HIPS/SBS416R-TSE (1:1:1) and PPE/HIPS/SBS416R-IM (1:1:1) blends. a high content of PB in the matrix combined with a low content of PS (PPE/HIPS-22) or low content of PB in the matrix combined with a high content of PS (PPE/HIPS-40) lead to lower impact resistance, compared with PPE/HIPS/SBS blends, at 24 wt% of SBS content. For the PPE/HIPS/SBS blend with a ratio 1:1:1, where the PS content was more significant than the other components and with an adequate component distribution. The toughening was more influenced by the blend composition than the blending process since the PPE/HIPS/SBS416 blends formulated by both methods presented similar values. Therefore, an appropriate distribution of the block copolymer is crucial to excellent impact resistance performance. Consequently, the control of phase separation between PPE and PB allows adequate interfacial adhesion and outstanding impact resistance. The PPE/HIPS/SBS blends are fascinating because of the combination of the high chemical, thermal, and mechanical properties of PPE with the elastomeric behavior of SBS and the excellent processability of HIPS. These blends are also of scientific and technological interest from the performance and cost viewpoints because they allow the custom formulation of compositions having predetermined properties ranging between those of SBS/HIPS and PPE by controlling the ratio of the components. The lactic employed in this contribution enables the tailoring of high-performance polymer blends, improving processability and reducing cost, where the blends with excellent performance could be used in the automotive industry, for example, in bumpers. Due to the versatility of these blends, the evaluation of the impact resistance varying the PPE:HIPS:SBS ratios is pending for future work. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app142210264/s1](https://www.mdpi.com/article/10.3390/app142210264/s1)]([https://www.mdpi.com/article/10.3390/app142210264/s1](https://www.mdpi.com/article/10.3390/app142210264/s1)), Figure S1. Storage modulus (G\({}^{\prime}\)) and viscous modulus (G\({}^{\prime\prime}\)) as a function of SBS content of the poly(2,6-dimethyl-1,4-phenylene ether) (P)/high-impact polystyrene (H)/styrene-butadiene-styrene (S) solprene 411 radial copolymer (S411R) P/H/S411R blends formulated by internal mixing (IM) versus P/H-22-IM. Figure S2.