We report on shear startup data for two wormlike micellar solutions, differing only in concentration and type of two binding aromatic sodium salts. The surfactant molecule is cetylpiridinium chloride at a fixed concentration (100 mM). Sodium salicylate (NaSal) and diclofenac sodium (Diclo) are used as binding salts at concentrations 68 mM NaSal and 52 mM Diclo such that both systems are fully entangled and their linear viscoelastic response is essentially identical. Both systems show the linear response typical of a wormlike micellar solution, with terminal behavior at low frequencies, a well-defined moduli crossover, and a plateau modulus. In the nonlinear regime, however, the behavior of the two systems is totally different, suggesting that the molecular structure difference of the salts and their binding activity to the surfactant molecule are both crucial to determine the fast flow behavior. The NaSal solution shows a very complex rheological response, with strain hardening and very sharp stress peaks, whereas the solution containing Diclo behaves much like ordinary linear polymers, exhibiting pronounced overshoots as well as moderate undershoots in the transient shear viscosity, before approaching the steady state. This polymerlike behavior has also been proved by successfully comparing data with predictions of a constitutive equation recently adopted for both entangled polymers and linear wormlike micelles. As far as NaSal is concerned, a phenomenological model based on rubber network theory is developed, which describes the flow singularities. A physical interpretation of the different behavior in the nonlinear regime is also suggested.
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March 2023
Research Article|
March 01 2023
On the startup behavior of wormlike micellar networks: The effect of different salts bound to the same surfactant molecule
Rossana Pasquino
;
Rossana Pasquino
a)
1
Department of Chemical, Materials, and Industrial Production Engineering, Federico II University
, P.le Tecchio 80, 80125 Naples, Italy
a)Author to whom correspondence should be addressed; electronic mail: r.pasquino@unina.it
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Pietro Renato Avallone
;
Pietro Renato Avallone
1
Department of Chemical, Materials, and Industrial Production Engineering, Federico II University
, P.le Tecchio 80, 80125 Naples, Italy
2
Department of Engineering, University of Sannio
, Piazza Roma 21, 82100 Benevento, Italy
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Salvatore Costanzo
;
Salvatore Costanzo
1
Department of Chemical, Materials, and Industrial Production Engineering, Federico II University
, P.le Tecchio 80, 80125 Naples, Italy
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Ionita Inbal
;
Ionita Inbal
3
Department of Biotechnology and Food Engineering, Russell Berrie Nanotechnology Institute
, Technion, Haifa Israel
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Dganit Danino;
Dganit Danino
3
Department of Biotechnology and Food Engineering, Russell Berrie Nanotechnology Institute
, Technion, Haifa Israel
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Vincenzo Ianniello
;
Vincenzo Ianniello
1
Department of Chemical, Materials, and Industrial Production Engineering, Federico II University
, P.le Tecchio 80, 80125 Naples, Italy
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Giovanni Ianniruberto
;
Giovanni Ianniruberto
1
Department of Chemical, Materials, and Industrial Production Engineering, Federico II University
, P.le Tecchio 80, 80125 Naples, Italy
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Giuseppe Marrucci
;
Giuseppe Marrucci
1
Department of Chemical, Materials, and Industrial Production Engineering, Federico II University
, P.le Tecchio 80, 80125 Naples, Italy
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Nino Grizzuti
Nino Grizzuti
1
Department of Chemical, Materials, and Industrial Production Engineering, Federico II University
, P.le Tecchio 80, 80125 Naples, Italy
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a)Author to whom correspondence should be addressed; electronic mail: r.pasquino@unina.it
J. Rheol. 67, 353–364 (2023)
Article history
Received:
July 26 2022
Accepted:
November 15 2022
Citation
Rossana Pasquino, Pietro Renato Avallone, Salvatore Costanzo, Ionita Inbal, Dganit Danino, Vincenzo Ianniello, Giovanni Ianniruberto, Giuseppe Marrucci, Nino Grizzuti; On the startup behavior of wormlike micellar networks: The effect of different salts bound to the same surfactant molecule. J. Rheol. 1 March 2023; 67 (2): 353–364. https://doi.org/10.1122/8.0000537
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