Polymer Blends: Principles and Applications: Part 1. Polymer-Polymer Miscibility and Applications of Miscible Blends

Abstract

Thermodynamic discussion on the miscibility between dissimilar polymers leads to: (i) the contribution of combinatorial entropy of mixing to the miscibility is negligibly small and (ii) the miscibility is mostly caused by the hydrogen bonding-type intermolecular specific interactions and the repulsive intramolecular interactions in random copolymers. By analyzing the fee energy curve, the free energy of mixing as a function of composition, phase diagrams are described in terms of the binodal curve and the spinodal curve. Criterions of polymer-polymer miscibility are deduced in the framework of such thermodynamic discussion. The polymer-polymer miscibility is applied: (i) to improve melt-processability (PPE/PS), (ii) to improve ozone resistance (NBR/PVC), (iii) to reduce optical anisotropy (to provide zero-birefringence plastics), (iv) to improve heat resistance (PEEK/PET), and (v) to make materials flexible (PVC/EVA).