The local structure of blends of polystyrene and poly(2,6‐dimethylphenylene oxide)

Polystyrene (PS) and poly(2,6‐dimethylphenylene oxide) (PPO) are miscible over the complete composition range. The addition of 30–40% PPO to PS changes the mechanical behavior of the material from brittle to tough and ductile. The x‐ray scattering curves from unoriented and oriented samples of PS and of PPO are compared with those from a 50/50 blend. The introduction of PPO into PS disrupts microsegregation of phenyl groups into stacks which are a feature of the pure polymer and which may be responsible for formation of sharp shear bands and brittle behavior of PS. The local structure of the blend is significantly different from both PS and PPO.