Processing of Polypropylene-Organic Montmorillonite Nanocomposite by Equal Channel Multiangular Extrusion

By the example of polypropylene-organic montmorillonite composite (PP-OMMT), the abilities of the method of equal channel multiangular extrusion have been studied with respect to the modification of the structure and the properties of polymeric nanocomposites. With using X-ray structure analysis, TEM, DSC, and dilatometry, it has been demonstrated that this kind of processing provides an additional intercalation of the polymer into OMMT tactoids with the succeeding exfoliation and facilitates an increase in the aspect ratio, the degree of platelet orientation, the crystalline lamellar thickness, and a decrease in the dispersion of the crystallite thickness, as well as the formation of biaxial orientation of the OMMT and PP crystals. The observed structure rearrangements determine enhanced microhardness, ductility, and the heat distortion temperature of the PP-OMMT composite.

Crystallite Thickness Estimates from Precession Electron Diffraction Patterns for Structural Fingerprinting in the Quasi-kinematic Limit

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Crystallite size distribution of clay minerals from selected Serbian clay deposits

The BWA (Bertaut-Warren-Averbach) technique for the measurement of the mean crystallite thickness and thickness distributions of phyllosilicates was applied to a set of kaolin and bentonite minerals. Six samples of kaolinitic clays, one sample of halloysite, and five bentonite samples from selected Serbian deposits were analyzed. These clays are of sedimentary volcano-sedimentary (diagenetic), and hydrothermal origin. Two different types of shape of thickness distribution were found - lognormal, typical for bentonite and halloysite, and polymodal, typical for kaolinite. The mean crystallite thickness (T BWA) seams to be influenced by the genetic type of the clay sample.