Poly(styrene‐ <i>block</i> ‐butadiene‐ <i>block</i> ‐styrene‐ <i>block</i> ‐butadiene) and poly(styrene‐ <i>block</i> ‐butadiene‐ <i>block</i> ‐methyl methacrylate) copolymers as compatibilizers in PPO–SAN blends. I. Morphology and fracture behavior

Abstract

The toughness behavior of PPO–SAN blends with the modifier poly(styrene-block-butadiene) (SBSB) and with poly(styrene-block-butadiene-block-methyl methacrylate) copolymers (SBM) under impact loading conditions has been investigated. The observed morphology of blends compatibilized with SBM, in which the rubber phase discontinuously accumulated at the PPO–SAN interface, correlated with about 20 times higher energy dissipation up to maximum force and about seven times higher deformation capacity compared to pure PPO–SAN blends. In contrast, the fracture behavior of the SBSB-modified blends was not as strongly dependent on the rubber content. It is especially noteworthy that although the SBM modification resulted in a strong increase in toughness of the PPO–SAN blends, no decrease in stiffness could be found with up to 15% rubber additions. The values of Young's moduli remained at the same high level of the nonmodified material. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2037–2045, 2000