Suppressing phase coarsening in immiscible polymer blends using nano-silica particles located at the interface

The morphologies of polymer blends generated during processing are usually unstable and phase coarsening often occurs in the melt state, so suppressing the morphology coarsening is crucial to obtain polymer blends with tailored and stable structure and properties. The effect of nano-silica particles located at the interface on the phase coarsening of a polypropylene (PP)/polystyrene (PS) blend was studied in this work. In co-continuous 50/50PP/PS blend, the particles at the interface can effectively suppress the coarsening process even at a very low particle loading. Real-time observation conducted by using an optical microscope equipped with a camera and a hot stage showed that a small loading of particles has little effect on the retraction process but can suppress the coalescence and at high loading of particles, both the retraction and coalescence process can be significantly suppressed. The suppressing effect towards the coalescence was confirmed in 70/30 blend with PS phase as the dispersed phase. The stabilization mechanism used in particle stabilized emulsions was adopted to explain the suppressing effect of nano-silica particles located at the interface towards the phase coarsening of PP/PS blends.