Nano composites have unique properties which depend to a large extent on the quality of the nanoparticle dispersion. An outstanding issue is the quantitative measure of fillers that are actually dispersed to dimensions below a particular aggregate size by the mixing processes. We have developed two variants of a method for evaluating the content of dispersed nano-sized particles using small angle X-ray scattering (SAXS). We therefore use the well known Porod integral of the measured intensity. In our experiments the range of scattering vectors h is from 0.1 to 3 nm-1 (dimensional range of about 2 – 100 nm). The ratio of the filler volume fraction WF calculated from the Porod integral to the actual filler volume fraction (WD) provides a quantitative estimation of the quality of the nano-scale dispersion process, as the fraction of nano-fillers that were successfully dispersed to a scale below about 100 nm. In the case of significant impurities in the matrix, this calculation may be incorrect. If the particle shape is known and the SAXS pattern has a distinctive peak, the quantitative estimation of the dispersion quality (nano index: WF/WD) can be estimated by the experimental and calculated (from WD) peak area comparison.
Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2012: Advanced Materials, CNTs, Particles, Films and Composites (Volume 1)
Published: June 18, 2012
Pages: 45 - 47
Industry sector: Advanced Materials & Manufacturing
Topics: Materials Characterization & Imaging