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Comb and Branch‐on‐Branch Model Polystyrenes with Exceptionally High Strain Hardening Factor SHF > 1000 and Their Impact on Physical Foaming

Faust, Lorenz 1; Röpert, Marie-Christin 1; Esfahani, Masood K. 1; Abbasi, Mahdi; Hirschberg, Valerian 1; Wilhelm, Manfred 1
1 Institut für Technische Chemie und Polymerchemie (ITCP), Karlsruher Institut für Technologie (KIT)

Abstract:

The influence of topology on the strain hardening in uniaxial elongation is investigated using monodisperse comb and dendrigraft model polystyrenes (PS) synthesized via living anionic polymerization. A backbone with a molecular weight of M$_{w,bb}$ = 310 kg mol$^{–1}$ is used for all materials, while a number of 100 short (SCB, M$_{w,scb}$ = 15 kg mol$^{–1}$) or long chain branches (LCB, M$_{w,lcb}$ = 40 kg mol$^{–1}$) are grafted onto the backbone. The synthesized LCB comb serves as precursor for the dendrigraft-type branch-on-branch (bob) structures to add a second generation of branches (SCB, M$_{w,scb}$ ≈ 14 kg mol$^{–1}$) that is varied in number from 120 to 460. The SCB and LCB combs achieve remarkable strain hardening factors (SHF) of around 200 at strain rates greater than 0.1 s$^{–1}$. In contrast, the bob PS reach exceptionally high SHF of 1750 at very low strain rates of 0.005 s$^{–1}$ using a tilted sample placement to extend the maximum Hencky strain from 4 to 6. To the best of the authors’ knowledge, SHF this high have never been reported for polymer melts. Furthermore, the batch foaming with CO$_{2}$ is investigated and the volume expansions of the resulting polymer foams are correlated to the uniaxial elongational properties.


Verlagsausgabe §
DOI: 10.5445/IR/1000151498
Veröffentlicht am 19.10.2022
Originalveröffentlichung
DOI: 10.1002/macp.202200214
Scopus
Zitationen: 5
Web of Science
Zitationen: 6
Dimensions
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Technische Chemie und Polymerchemie (ITCP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 1022-1352, 0025-116X, 1521-3935
KITopen-ID: 1000151498
Erschienen in Macromolecular Chemistry and Physics
Verlag Wiley-VCH Verlag
Band 224
Heft 1
Seiten Art.-Nr.: 2200214
Vorab online veröffentlicht am 18.09.2022
Nachgewiesen in Web of Science
Scopus
Dimensions
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