Macroscopically homogeneous mixture of two or more different species of polymer.
Notes:
In most cases, blends are homogeneous on scales larger than several times the wavelengths of visible light.
In principle, the constituents of a blend are separable by physical means.
No account is taken of the miscibility or immiscibility of the constituent macromolecules, i.e., no assumption is made regarding the number of phase domains present.
The use of the term polymer alloy for a polymer blend is discouraged, as the former term includes multiphase copolymers but excludes incompatible polymer blends.
The number of polymeric components which comprise a blend is often designated by an adjective, viz. binary, ternary, quaternary, etc.