English Abstract

Heterogeneous Structure in Elastomers and Polymer Nanotechnology : Part II. Studies on Miscibility and Phase Separation in Polymer Alloys & Blends and Their Development

Toshio NISHI
Emeritus Professor of The University of Tokyo and Tokyo Institute of Technology
Nippon Gomu Kyokaishi,(2019),92(3),121-127 General Review in Japanese

Basic concepts in polymer alloys & blends are illustrated based on our experimental studies on several miscible polymer blends with phase diagram.
From poly (vinyl methyl ether)/polystyrene mixtures we could find out lower critical solution temperature type phase diagram. The diagram is highly molecular weight dependent and the behavior can be explained by the extension of polymer solution theory to polymer/polymer systems. Moreover, phase separation behavior in this system can be classified into nucleation & growth and spinodal decomposition.
From poly (vinylidene fluoride)(PVF2)/poly (methyl methacrylate) mixtures, we could find out melting point depression of PVF2 and even calculate the interaction parameter based on Nishi-Wang Equation.
From poly (vinyl chloride)(PVC)/copolyester thermoplastic elastomer (TPE) mixtures, we could control the dynamic mechanical properties of the system due to the miscibility between PVC and soft segment of TPE. The state of the miscibility influences the impact strength of the alloys.
Finally, from polycarbonate/poly (ethylene terephthalate) blends, we could show the importance of transesterification between two polymers.
These experimental facts can be generalized to study polymer alloys & blends and are essential for the application of these complex systems in practice.

Keywords: Miscibility, Interaction Parameter, Phase Diagram, Critical Solution Temperature, Melting Point Depression, Nishi-Wang Equation, Spinodal Decomposition, Transesterification