MODEL EXPERIMENTS CONCERNING MORPHOLOGY DEVELOPMENT DURING THE INITIAL-STAGES OF POLYMER BLENDING

In order to investigate the mechanisms of morphology development in polymer-polymer blending, a model experiment is developed which allows the matrix to be dissolved away so that the dispersed phase may be observed directly using scanning electron microscopy (SEM). The dispersed phase for the model experiments is an amorphous nylon. The matrix phase is a polystyrene. These model experiments dramatically reveal the primary modes of particle deformation and the nature of the morphologies at short mixing times. The initial mechanism of morphology development involves the dragging of a large particle of the dispersed phase along a hot surface such as the mixer walls. This dragging action results in the formation of sheets or ribbons of the dispersed phase. These sheets or ribbons become unstable due to the effects of shear and interfacial tension. Holes develop in the ribbons which grow in size and concentration until a fragile lace structure is formed. This lace structure breaks into irregularly shaped particles which are then broken up into nearly spherical particles.