X-ray scattering studies of flow induces alignment in polymer nanocomposites and new development in wire and cable and pressure sensitive adhesive technologies by Dr. Saswati Pujari

Location and Date: 
Wednesday, 6 February, 2019, 4:00 pm, Seminar Hall, Second Floor, DESE-CESE Building


Polymer nanocomposites are a new class of materials, in which a nanoscale particle is dispersed in a polymer matrix. These materials are of increasing interest because of significant property enhancement achieved at small volume fraction of the nanoparticles. Often these nanoparticles are of anisotropic shapes like discs (clay, graphene) and rods (carbon nanotubes). The anisotropic shape of the nanoparticles causes them to align when subject to various flow conditions during processing. Since the physical and thermal properties of the nanocomposites strongly depend on the alignment of the nanoparticles, it becomes essential to develop methods to characterize and predict nanoparticle alignment during flow. In this talk I would like to present a part of my PhD work which deals with characterization of flow induced alignment in model multi-walled carbon nanotube (MWNT), and clay dispersions during simple shear flow. For the MWNT dispersions, I will detail how time resolved x-ray scattering was used to get insight into the mechanism of structural changes in the vorticity (1-3) and flow gradient (1-2) plane of simple shear flow. Time resolved measurement of structure was made possible by the high intensity and brilliance of synchrotron x-ray radiation, where these experiments were conducted. Accompanying rheological measurements enabled us to infer the consequences of such structural changes to the rheological behavior of these materials. Among some of the most interesting results were extremely long transients to reach steady state and partial relaxation of anisotropy when flow was stopped. Further, I will use the studies on clay dispersions to demonstrate the flow induced structural behavior of disc-like particles and how x-ray scattering can reveal structure at multiple length scales – individual particles and particle networks.
The second part of my talk will focus on topics of industrial research including development of new materials and technologies for advanced wire and cable applications and pressure sensitive adhesive applications. The talk will cover material requirements in these application areas and key technologies developed through my research.