BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Keynote 7 - Molecular Rheology of Entangled Polymeric Fluids: New Discoveries and Remaining Challenges DTSTART;VALUE=DATE-TIME:20181211T105000Z DTEND;VALUE=DATE-TIME:20181211T113000Z DTSTAMP;VALUE=DATE-TIME:20260523T152713Z UID:indico-contribution-89-489@lindico453.srv.lu.se DESCRIPTION:Speakers: Bamin Khomami (Chemical & Biomolecular Engineering\, The University of Tennessee\, USA)\nQuantitative understanding of the inf luence of environmental variables on the dynamic evolution of microstructu re in polymeric fluids plays a central role in soft matter physics as well as the processing of a wide variety of soft materials. Atomistic simulati on via non-equilibrium molecular dynamics (NEMD) offer a viable alternativ e to experiment wherein the dynamics of individual macromolecules can be t racked independently\, thus allowing for relevant calculations of their si ngle-chain configurational properties as well as the individual chain cont ributions to bulk-average properties. Specifically\, large scale NEMD simu lation results of entangled polymeric fluids allow examination of the fund amental tenants of reputation/ tube based theories including calculation o f essential variables such as the tube orientation tensor\, tube stretch\, and disengagement and Rouse times.\nIn this presentation\, I will briefly review the progress made in fundamental understanding of non-equilibrium dynamics of polymeric melts as well as the remaining challenges in develop ment of a unified approach for quantitative prediction of dynamics of this class of fluids in processing flows commonly used to produce structural a nd functional soft materials. Specifically\, I will discuss\, Non-Equilibr ium Molecular Dynamics Simulations (NEMD) results of linear monodisperse e ntangled macromolecular melts in shear and extensional flows that depict e xistence of new phenomena that challenges the fundamental tenants of reput ation/tube based theories and models used to describe fast flow of entangl ed polymeric fluids. In turn\, the intricate connection between single cha in dynamics and the macroscopic response of this class of fluids including the intriguing phenomena of shear banding and configurational microphase separation in planar extensional flows will be discussed.\nAcknowledgments : Financial support was provided by the National Science Foundation under Grant No. CBET-1602890.Computational resources for this project were provi ded by allocation of advanced computational resources by the National Inst itute for Computational Sciences (NICS) and the Oak Ridge National Laborat ory Joint Institute for Computational Sciences. This work also used the Ex treme Science and Engineering Discovery Environment (XSEDE)\, which is sup ported by National Science Foundation grant number ACI-1548562/TG-CTS15005 4.\n\nhttps://lindico453.srv.lu.se/event/67/contributions/489/ LOCATION:Elite Hotel Ideon Tera URL:https://lindico453.srv.lu.se/event/67/contributions/489/ END:VEVENT BEGIN:VEVENT SUMMARY:Contr. Talk 8 - Shear Effects on Soft Colloids DTSTART;VALUE=DATE-TIME:20181211T103000Z DTEND;VALUE=DATE-TIME:20181211T105000Z DTSTAMP;VALUE=DATE-TIME:20260523T152713Z UID:indico-contribution-89-488@lindico453.srv.lu.se DESCRIPTION:Speakers: Jorg Stellbrink (JCNS-1\, Forschungszentrum Julich\, 52425 Julich\, Germany)\nWhereas the collective response to external shea r of soft colloids is frequently investigated [1\,2]\, observations of she ar-induced effects on the single particle level are still scarce. Therefor e we investigated this intraparticle “brush deformation” of polybutadi ene (PB) star and linear polymers by rheology and Rheo-SANS [3\, 4]. Excel lent agreement between experiment and theory with respect to the amount of shear deformation and shear thinning for star polymers with varying funct ionality\, f\, was found. Surprisingly\, two decay modes (“fast” and “slow” modes) were observed in flow curves of star polymers\, indicati ng a hierarchical deformation of the polymeric corona. In binary mixtures it was observed that fast and slow modes originating from the star polymer s were strongly affected by the addition of linear homopolymer\, which inf luenced the shear induced ‘brush deformation’ of star polymers. We fou nd macroscopic phase separation upon increasing concentrations of linear p olymer and shear-induced microphase separation (coil-to-globule transition ) by means of Rheo-SANS experiments.\n\nhttps://lindico453.srv.lu.se/event /67/contributions/488/ LOCATION:Elite Hotel Ideon Tera URL:https://lindico453.srv.lu.se/event/67/contributions/488/ END:VEVENT BEGIN:VEVENT SUMMARY:Keynote 6 - Nonlinear rheology of polydisperse blends of entangled linear polymers: Rolie-Double-Poly models DTSTART;VALUE=DATE-TIME:20181211T095000Z DTEND;VALUE=DATE-TIME:20181211T103000Z DTSTAMP;VALUE=DATE-TIME:20260523T152713Z UID:indico-contribution-89-487@lindico453.srv.lu.se DESCRIPTION:Speakers: Daniel Read (Department of Applied Mathematics\, Uni versity of Leeds\, UK)\nWhilst there has been much success in modeling the linear and nonlinear rheology of monodisperse entangled linear polymers\, progress in the constitutive modeling of polymeric materials continues to lag behind the needs of industry. Industrially sourced polymers are typic ally polydisperse (comprising a broad distribution of molecular weights)\, making their rheology more suitable for processing but also more difficul t to predict. To date\, there are no molecular-based constitutive models t hat are practically suitable for describing industrially relevant polymers in industrially relevant flows. We extend but strongly simplify the Read et al. model [Read et al.\, J.Rheol. 56\, 823-873 (2012)]\, which is able to predict the linear and nonlinear rheology of bidisperse blends but is p rohibitively complex for industrial use. We propose a pair of simplified t ube models for polydisperse melts of entangled linear polymers that combin e the success of the double reptation approximation [des Cloizeaux\, Europ hys. Lett. 5\, 437-442 (1988)] in the linear regime with the success of th e Rolie-Poly constitutive equation [Likhtman et al.\, J. Non-Newton. Fluid Mech.114\, 1-12 (2003)] in the nonlinear regime. For binary blends\, We s how that these models naturally identify the effects from couplings betwee n constraint release and chain retraction (i.e. the so-called "enhanced st retch relaxation time"). We generalize to a multi-component (polydisperse) model\, based on the same underlying principles. Both of our models are i n qualitative\, and largely quantitative\, agreement with experimental dat a for bidisperse and polydisperse melts of entangled linear polymers.\n\nh ttps://lindico453.srv.lu.se/event/67/contributions/487/ LOCATION:Elite Hotel Ideon Tera URL:https://lindico453.srv.lu.se/event/67/contributions/487/ END:VEVENT END:VCALENDAR