Microstructural Evolution of PP/EPDM/Organoclay Nanocomposites in a Twin Screw Extruder

Abstract

The offline Microstructure of nanocomposites based on Poly-Propylene (PP), Ethylene-Propylene Diene Monomer (EPDM) and Cloisite 15A along the twin screw extruder barrel was investigated by X-Ray diffraction, Transmission Electron Microscopy (TEM) and rheological measurements. To assess the effect of screw zones, the microstructural development of nanocomposites along the screw was investigated. Accordingly, dead-stop experiment samples were taken at four different positions of the extruder after abruptly stopping the machine and opening the barrel. Effect of clay loading on the evolution of morphology in the extruder was studied. X-Ray diffraction results showed that at lower clay contents (up to ∼7 wt.%), the intercalation process is independent of screw geometry and accomplishes as soon as the matrix is melted; and on the other hand, excessive melt mixing of the samples containing higher clay loadings (10 wt.%) might lead to the collapse of silicate layers and consequently poor degrees of intercalation/exfoliation. Results were confirmed by TEM micrographs and also XRD patterns of the nanocomposites sensitively detecting the microstructural changes of the samples.