Scanning electron microscopy studies of polymer melt devolatilization

Abstract The devolatilization mechanism of polystyrene was studied by scanning electron microscopy. Strands of molten polystryene, containing 2,300 ppm styrene, and molten polystyrene containing 5% pentane, were extruded into a heated vacuum chamber. The strands were abruptly frozen, then fractured under liquid nitrogen and their morphology studied with scanning electron microscopy. A rich variety of morphological features in the core and on the surface of strands was discovered. These include micro‐ and miniblisters, fibrous structures, and crusty nodules on the inner surfaces of large macrobubbles. The source of these morphological features and their relevance to devolatilization is discussed.