Investigating the effect of surface modification on the dispersion process of polymer nanocomposites

Achieving controlled nanoparticle dispersion through melt processing has been challenging as processing-structure rules for polymer nanocomposites are still not well-defined. This work focuses on developing a quantitative understanding of the filler–matrix compatibility and melt mixing parameters on the dispersion of nanoparticles. Filler-matrix compatibility was varied by surface modification of silica nanoparticles. A twin screw extruder was used to prepare the nanocomposites and TEM imaging and image analysis were used to quantitively characterize the microstructure. It was found that matrix–filler compatibility strongly affected the method of agglomerate breakdown and dispersion. Under similar conditions, compatible systems tended to disperse via rupture of agglomerates while incompatible systems were found to disperse via erosion. A map was created to predict the dispersion mechanism as a function of processing conditions and system compatibility and systems from this study and literature were found to be in good agreement with the map.