Morphology of HDPE/(PEC/PS) blends modified with SEBS copolymers

In this study, immiscible blends of HDPE and an amorphous glassy polymer were compatibilized with styrene‐hydrogenated butadiene block copolymers. The glassy phase consisted of either pure PS or a miscible blend of PS and polyether copolymer (PEC); PEC is similar to poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO). The morphology of these two‐phase mixtures depended on physical characteristics of the components and the method of fabrication. Suitable copolymers increased the degree of dispersion and minimized heterogeneities resulting from the inherent incompatibility of the individual phases. Further reduction in the phase size and increased adhesion between the components of modified blends were achieved by increasing the composition of PEC in the glassy phase. It was concluded that favorable exothermic mixing between PEC and PS endblocks of the copolymers provided an additional driving force for compatibilization. Results from dynamic mechanical thermal analysis suggests that penetration by the copolymers into the homopolymer phases is not complete.