The problem of miscibility of polymers is one of the most important problems at present. The point is is that new polymeric materials are now created, as a rule, not by synthesizing new polymers, but by composing mixtures of the known polymers. Therewith, it is essential to consider not only mixed composites, into which components of the mixture are injected in comparable amounts, but also the introduction of micro additions of polymers, their surface modification, etc. There are also problems appearing in this case, such as microphase separation, facilities to control the composition and size of microphases, etc. Having no way of discussing numerous publications which have appeared recently in this field, let us analyze one of possible ways of predicting the miscibility of polymers and estimating the composition of microphases.

One of possible ways of looking at the problem of predicting the miscibility of polymers is the application of criterion (XII.21), which is intended for analyzing the solubility of polymers. Therewith, if one polymer is introduced in small amounts into another polymer, the former of them is considered as the 'polymer' and the latter - as the 'solvent' when criterion (XII.21) is applied. In principle, the following variants are probable.

1. When criterion (XII.21) is used, it turns out that, in all cases, the left part of the criterion is greater than the right part, i.e. total incompatibility takes place. Under all cases we mean those when the first polymer is introduced in small quantities into the second one and,...