Miscibility criterion

This sub-problem considers the mixture properties. Mixture properties can be categorized into two types. Properties such as selectivity, solvent power etc., are based on infinite dilution activity coefficients, which are independent of composition and hence only structural information is needed for their calculation. Properties such as complete or partial miscibility of solvent with another constituent is handled by discritizing the composition range from 0 to 1 into n divisions and verifying the miscibility criterion at those points. The difference between pure component property constraints and mixture property constraints is that the former are linear and the latter are non-linear. Those satisfying the mixture property constraints are further analyzed in sub-problem 4. 

The solubility of 10-15 parts of CTPnBA in 100 parts DGEBA (Epon 828) at 25 C was the miscibility criterion for the two resins. 

If X must be less than 0.5 for full polymer-solvent miscibility, and Xs is about 0.3, it follows that Xh must be very small to meet the miscibility criterion, and that 5, and Sj must have very similar values. Specific interactions (such as hydrogen bonding between molecules of type i and type j to a greater extent than i-i and j-j hydrogen bonding) can result in the lower Xh thus enhance the mutual solubility. 

---