Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering
Autor: | Wim Pyckhout-Hintzen, Dietmar Auhl, Nikolaos Hadjichristidis, Nino Ruocco, Dieter Richter, Christian Bailly, L. G. Leal, Peter Lindner, Andreas Wischnewski |
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Přispěvatelé: | RS: FSE AMIBM, AMIBM, UCL - SST/IMCN/BSMA - Bio and soft matter |
Rok vydání: | 2016 |
Předmět: |
Materials science
Polymers and Plastics CONSTITUTIVE-EQUATIONS 02 engineering and technology Neutron scattering 01 natural sciences Molecular physics NONLINEAR RHEOLOGY Inorganic Chemistry Viscosity Matrix (mathematics) Optics CHAIN CONFORMATION Phase (matter) 0103 physical sciences Materials Chemistry H-POLYMERS POM-POM MODEL TOPOLOGICAL CONSTRAINTS chemistry.chemical_classification 010304 chemical physics Deformation (mechanics) Scattering business.industry Organic Chemistry technology industry and agriculture MOLECULAR RHEOLOGY Polymer 021001 nanoscience & nanotechnology Small-angle neutron scattering CONSTRAINT-RELEASE ENTANGLED POLYMERS chemistry POLYMER MELTS 0210 nano-technology business |
Zdroj: | Macromolecules, 49(11), 4330-4339. American Chemical Society Macromolecules, Vol. 49, no.11, p. 4330-4339 (May 2016) |
ISSN: | 1520-5835 0024-9297 |
DOI: | 10.1021/acs.macromol.5b02786 |
Popis: | We present a small angle neutron scattering (SANS) investigation of a blend composed of a dendritic polymer and a linear matrix with comparable viscosity in start-up of an elongational flow at T-g + 50. The two-generation dendritic polymer is diluted to 10% by weight in a matrix of a long well-entangled linear chains. Both components consist of mainly 1,4-cis-polyisoprene but differ in isotopic composition. The resulting scattering contrast is sufficiently high to permit time-resolved measurements of the system structure factor during the start-up phase and to follow the retraction processes involving the inner sections of the branched polymer in the nonlinear deformation response. The outer branches and the linear matrix, on the contrary, are in the linear deformation regime. The linear matrix dominates the rheological signature of the blend and the influence of the branched component can barely be detected. However, the neutron scattering intensity is predominantly that of the (branched) minority component so that its dynamics is clearly evident. In the present paper, we use the neutron scattering data to validate the branch point withdrawal process, which could not be unambiguously discerned from rheological measurements in this blend. The maximal tube stretch that the inner branches experience, before the relaxed outer arm material is incorporated into the tube is determined. The in situ scattering experiments demonstrate for the first time the leveling-off of the strain as the result of branch point withdrawal and chain retraction directly on the molecular level. We conclude that branch point motion in the mixture of architecturally complex polymers occurs earlier than would be expected in a purely branched system, presumably due to the different topological, environment that the linear matrix,presents to the hierarchically deep-buried tube sections. |
Databáze: | OpenAIRE |
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