Polymer Blends

Miscibility and compatibility in polymer blends is a topic of great academic and industrial importance. This is because miscibility and compatibility contribute to morphology, properties, and performance. Miscibility results in one phase; compatibility creates a disperse phase with size and stability determined by interfacial interactions. Miscible polymer properties are averaged similar to a plasticizer polymer, and compatible polymers retain properties of each component, such as toughening or reinforcement. With miscible polymer blends the continuous phase dominates properties; the disperse phase contributes via stress transfer. This chapter revisits the criteria for miscibility or compatibility in polymer blends and the contributors of compatibility compared with miscibility and incompatibility. Development of copolymers and their blending with thermosets and thermoplastics result in complex two-phase morphologies. The dynamics of phase separation observed in polymer blends leading to different morphologies and the criteria for phase separation is explained. A nanometer-dispersed phase requires strong interfacial interactions to stabilize the large interfacial area, and this is favored by rapid spinodal phase separation compared with size diminution by high shear. Nanoblends open up a new arena for polymer blends, and research shows that nanoblends have outstanding optical and mechanical properties.