Polymer blends: fundamentals

A polymer blend is a mixture of at least two macromolecular substances, polymers or copolymers, in which the concentration of each polymeric ingredient is above 2 wt.%. Blends are either miscible or immiscible [1], The miscible polymer blends are homogeneous down to the molecular level. Their free energy and heat of mixing, \u394Gm 45 \u394H m 640 and 022\u394Gm/\u3c6>2>0, where \u3c6 is the volume fraction. In these blends, the domain size is comparable to the dimension of the macromolecular statistical segment, d<20 nm. The immiscible polymer blends are those where \u394Gm>0, and/or 022\u394G m/ 02\u3c62