Preferred Orientation of Organoclay in Nano composites by 3D-TEM and Directional SAXS Study

摘要

The state of clay dispersion and orientation has long been anessential issue in polymer nanocomposites, affecting many physicalproperties from mechanical modulus over gas permeability to flameretardation. Two frequently used characterization techniques for thedetermination of nanoclay morphology (i.e., exfoliation vs.intercalation, stacking sequence statistics) are transmission electronmicroscopy (TEM) and small-angle X-ray scattering (SAXS).However extracting information of clay dispersion and orientationusing these techniques requires a certain degree of careful dataanalysis, not well practiced in the community. Quantitative analysisof TEM has been shown to be capable of evaluating the extent ofsilicate exfoliation in polymer matrices'. In this work, we demonstratethe use of three-dimension at (3D) TEM and directional SAXSanalysis, which can provide quantitative and complimentarystructural information on clay orientation in polymer nanocomposites.The chosen nanocomposite system was based on melt-mixedethylene-vinyl acetate (EVA) copolymers and organoclays (cloisite,C20A). 3D TEM showed that the clay particles were mostlyintercalated and with preferred orientation as sketched in Figure 1parallel with the plane direction of the pressed film.