Elongational viscosity and brittle fracture of bidisperse blends of a high and several low molar mass polystyrenes

Wagner, Manfred H.; Narimissa, Esmaeil; Shahid, Taisir

doi:10.1007/s00397-021-01304-1

Cited by 14 publications

(6 citation statements)

References 43 publications

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“…The critical stretch at fracture, f c , is given by f c = U 3 k T ϕ with k being the Boltzmann constant and T the absolute temperature. This fracture criterion has been shown to be in agreement with experimental evidence of polymer melts and solutions, see, e.g., refs − .…”

Section: Ers Model With Dilutionsupporting

confidence: 84%

Rheology of Poly(α-olefin) Bottlebrushes: Effect of Self-Dilution by Alkane Side Chains

Wagner,

Hirschberg

2024

Macromolecules

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Bottlebrush polymers are combs with extremely high grafting density along their backbone chain. We consider the rheology of bottlebrush poly(α-olefins) with side chains ranging from 6 carbons [poly(1-octene)] to 16 carbons [poly(1octadecene)] as investigated by Loṕez-Barroń et al. (J. Rheol. 2019, 63 (6), 917−926). We argue that the backbone chain of poly(α-olefins) is diluted by the unentangled alkane side chains and that the rheology of poly(α-olefin) bottlebrushes is equivalent to that of poly(1-methylethylene), i.e., atactic polypropylene diluted by a low-molecular-weight solvent. We show that this approach is in agreement with the decreasing plateau modulus of the poly(α-olefins) with increasing side chain length, and it allows to replace empirical correlations by a relation based on physical arguments. The specific strong transient strain hardening in elongational flow shows similar features as observed for entangled solutions of linear polymers and can be explained by the enhanced relaxation of stretch model if self-dilution of the poly(α-olefins) is taken into account. Due to the large difference between the disengagement time d and Rouse time R , the orientation and stretch of backbone chains are well separated, and strain hardening starts after full orientation at Weissenberg numbers above Wi 0.3 R R =. The amount of strain hardening increases with increasing dilution, and at high Wi R , all poly(α-olefins) are expected to reach the same steady-state elongational stress.

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Section: Ers Model With Dilutionsupporting

confidence: 84%

Rheology of Poly(α-olefin) Bottlebrushes: Effect of Self-Dilution by Alkane Side Chains

Wagner,

Hirschberg

2024

Macromolecules

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“…This behavior is captured by the EIP model. 63 In Figure 5a, the behaviors of the solutions with 2 and 4 kg/mol OS are also very close to each other.…”

Section: Extensional Rheology and Dynamics Ofmentioning

confidence: 52%

“…As reported by Shahid et al, the samples containing 10% long PS chains (820 kg/mol) and 90% short chains with molecular weights of 72K, 34K, 23K, and 8.8K reach the same extensional steady-state viscosity when the Rouse time-based Weissenberg number Wi R > 1 (as long as the matrix is not stretched). This behavior is captured by the EIP model . In Figure a, the behaviors of the solutions with 2 and 4 kg/mol OS are also very close to each other.…”

Section: Extensional Rheology and Dynamics Of Polymers With Different...mentioning

confidence: 53%

When Polymer Chains Are Highly Aligned: A Perspective on Extensional Rheology

Huang

2022

Macromolecules

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We provide a Perspective on recent findings in extensional rheology for polymer melts and solutions with different macromolecular architectures. For linear polymer systems, we focus on the argument of flow-induced friction reduction and provide our comments from an experimental point of view. For branched polymers, we provide our understanding on how to control extensional viscosity for polymers with different zero-shear-rate viscosity based on recent experimental results of star and comb polymer melts. For ring polymers, we summarize the recent progress in extensional rheology and provide our view on what would be interesting for further investigation. On the basis of the above results and discussions, we show that extensional rheology is complicated for even very simple molecular architectures. More data from both experiments and simulations are important for improvement of a fundamental understanding and development of theories, which is essential for molecular design of polymer materials.

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“…On the other hand, fillers migrating parallel to the phase interface tend to remain stable on the phase interface either due to minimal influence from migration driving forces or negligible impact from migration driving forces. At the same time, the elongational viscosity of the PS phase increased [39], resulting in the distribution of GNPs in the fibrous PA6 phase.…”

Section: Molecular Dynamics Simulationmentioning

confidence: 98%

Enhancing the Thermal Conductivity of PS/PA6/GNPs Composites through Elongational Flow

Wen,

Chen,

Zhang

et al. 2024

Preprint

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Migration and distribution of thermal conduct fillers in polymer blend are key factors in the preparation of enhanced thermal conductivity composite. In this study, polystyrene(PS)/polyamides 6(PA6)/graphene nanoplatelets(GNPs) composites with enhanced thermal conductivity were prepared under elongational flow, and the migration and distribution of GNPs were investigated by molecular dynamics simulation and experiments. The results showed that when GNPs immigrate from PA6 phase to PS phase, the elongational flow caused the orientation of the PS phase and GNPs, reducing the migration rate of GNPs from the PA6 phase to the PS phase. At the same time, the stretching viscosity of the PS phase increases, which prevents GNPs entering the PS phase. As a result, GNPs remain within the PA6 phase near the interface of the two phases. The effective distribution density of GNPs increased, making it easier for them to interconnect and form thermal conduction paths, thereby improving the thermal conductivity of the composites. Particularly, the composite prepared under the elongational flow with the 50/50 vol ratio of PS/PA6, the in-plane thermal conductivity of PS/PA6/GNPs composites reached a maximum of 1.64 W/(m·K).

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Elongational viscosity and brittle fracture of bidisperse blends of a high and several low molar mass polystyrenes

Cited by 14 publications

References 43 publications

Rheology of Poly(α-olefin) Bottlebrushes: Effect of Self-Dilution by Alkane Side Chains

Rheology of Poly(α-olefin) Bottlebrushes: Effect of Self-Dilution by Alkane Side Chains

When Polymer Chains Are Highly Aligned: A Perspective on Extensional Rheology

Enhancing the Thermal Conductivity of PS/PA6/GNPs Composites through Elongational Flow

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