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Open AccessArticle

Small and Medium Amplitude Oscillatory Shear Rheology of Model Branched Polystyrene (PS) Melts

1
School of Chemical and Biomolecular Engineering, Pusan National University, Busan 46241, Korea
2
Institute of Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraβe 18, 76131 Karlsruhe, Germany
3
Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea
4
Department of Chemical Engineering and Biotechnology, Korea Polytechnic University, Siheung-Si, Gyeonggi-Do 15073, Korea
*
Author to whom correspondence should be addressed.
Polymers 2020, 12(2), 365; https://doi.org/10.3390/polym12020365
Received: 23 December 2019 / Revised: 9 January 2020 / Accepted: 1 February 2020 / Published: 7 February 2020
(This article belongs to the Section Polymer Physics)
:Linear and nonlinear rheological properties of model comb polystyrenes (PS) with loosely to densely grafted architectures were measured under small and medium amplitude oscillatory shear (SAOS and MAOS) flow. This comb PS set had the same length of backbone and branches but varied in the number of branches from 3 to 120 branches. Linear viscoelastic properties of the comb PS were compared with the hierarchical model predictions. The model underpredicted zero-shear viscosity and backbone plateau modulus of densely branched comb with 60 or 120 branches because the model does not include the effect of side chain crowding. First- and third-harmonic nonlinearities reflected the hierarchy in the relaxation motion of comb structures. Notably, the low-frequency plateau values of first-harmonic MAOS moduli scaled with Mw-2 (total molecular weight), reflecting dynamic tube dilution (DTD) by relaxed branches. Relative intrinsic nonlinearity Q0 exhibited the difference between comb and bottlebrush via no low-frequency Q0 peak of bottlebrush corresponding to backbone relaxation, which is probably related to the stretched backbone conformation in bottlebrush.
Keywords: Comb polymer; Bottlebrush polymer; Medium amplitude oscillatory shear (MAOS); FT rheology; Nonlinear parameter Comb polymer; Bottlebrush polymer; Medium amplitude oscillatory shear (MAOS); FT rheology; Nonlinear parameter
MDPI and ACS Style

Song, H.Y.; Faust, L.; Son, J.; Kim, M.; Park, S.J.; Ahn, S.-K.; Wilhelm, M.; Hyun, K. Small and Medium Amplitude Oscillatory Shear Rheology of Model Branched Polystyrene (PS) Melts. Polymers 2020, 12, 365.

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