Molecular design of multicomponent polymer systems. XIV. Control of the mechanical properties of polyethylene–polystyrene blends by block copolymers

The present investigation deals with the tensile mechanical properties of the melt‐blended polyethylene/polystyrene pair as controlled by poly(hydrogenated butadiene‐b‐styrene) copolymers. It is clearly demonstrated that moderate amounts of these copolymers (2–10%) significantly increase both the ultimate strength and elongation at break of blends of polystyrene with various types of polyethylene (low‐density, high‐density, linear low‐density, and hydrogenated polybutadiene) and synergistic effects may result. The mechanical performance is strikingly dependent on the molecular characteristics of the copolymers. Over a broad range of molecular weights (60,000–270,000), diblocks are more effective than graft, triblock, or star‐shaped copolymers. It is also demonstrated that using polymeric emulsifiers under usual processing conditions in the melt state is powerful technique for preparing valuable polymer alloys. Copyright © 1989 John Wiley & Sons, Inc.