Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering

Handle URI:
http://hdl.handle.net/10754/621382
Title:
Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering
Authors:
Ruocco, N.; Auhl, D.; Bailly, C.; Lindner, P.; Pyckhout-Hintzen, W.; Wischnewski, A.; Leal, L. G.; Hadjichristidis, Nikolaos ( 0000-0003-1442-1714 ) ; Richter, D.
Abstract:
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 Tg + 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. © 2016 American Chemical Society.
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC)
Citation:
Ruocco N, Auhl D, Bailly C, Lindner P, Pyckhout-Hintzen W, et al. (2016) Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering. Macromolecules 49: 4330–4339. Available: http://dx.doi.org/10.1021/acs.macromol.5b02786.
Publisher:
American Chemical Society (ACS)
Journal:
Macromolecules
Issue Date:
27-May-2016
DOI:
10.1021/acs.macromol.5b02786
Type:
Article
ISSN:
0024-9297; 1520-5835
Sponsors:
The authors express thanks for the financial support of the EU (ITN DYNACOP 214627 Marie Curie Network). They also acknowledge Drs. Q. Huang, M. Shivokhin, and D. J. Read for helpful and productive discussions on the evaluation of nonlinear rheology and scattering modeling. We also would like to thank the Institut Laue Langevin (ILL) for the availability of the neutron beam time.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorRuocco, N.en
dc.contributor.authorAuhl, D.en
dc.contributor.authorBailly, C.en
dc.contributor.authorLindner, P.en
dc.contributor.authorPyckhout-Hintzen, W.en
dc.contributor.authorWischnewski, A.en
dc.contributor.authorLeal, L. G.en
dc.contributor.authorHadjichristidis, Nikolaosen
dc.contributor.authorRichter, D.en
dc.date.accessioned2016-11-03T08:27:59Z-
dc.date.available2016-11-03T08:27:59Z-
dc.date.issued2016-05-27en
dc.identifier.citationRuocco N, Auhl D, Bailly C, Lindner P, Pyckhout-Hintzen W, et al. (2016) Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering. Macromolecules 49: 4330–4339. Available: http://dx.doi.org/10.1021/acs.macromol.5b02786.en
dc.identifier.issn0024-9297en
dc.identifier.issn1520-5835en
dc.identifier.doi10.1021/acs.macromol.5b02786en
dc.identifier.urihttp://hdl.handle.net/10754/621382-
dc.description.abstractWe 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 Tg + 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. © 2016 American Chemical Society.en
dc.description.sponsorshipThe authors express thanks for the financial support of the EU (ITN DYNACOP 214627 Marie Curie Network). They also acknowledge Drs. Q. Huang, M. Shivokhin, and D. J. Read for helpful and productive discussions on the evaluation of nonlinear rheology and scattering modeling. We also would like to thank the Institut Laue Langevin (ILL) for the availability of the neutron beam time.en
dc.publisherAmerican Chemical Society (ACS)en
dc.titleBranch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scatteringen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical Science Programen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.identifier.journalMacromoleculesen
dc.contributor.institutionUniversity of California Santa Barbara, Santa Barbara, CA, United Statesen
dc.contributor.institutionJülich Centre for Neutron Science-1, Forschungszentrum Jülich, Jülich, Germanyen
dc.contributor.institutionUniversité Catholique de Louvain, Louvain-La-Neuve, Belgiumen
dc.contributor.institutionMaastricht University, Maastricht, Netherlandsen
dc.contributor.institutionInstitut Laue-Langevin, Grenoble, Franceen
kaust.authorHadjichristidis, Nikolaosen
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