# Viscosity of ring polymer melts

Journal Article (Academic article)

We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts ?0,linear to their ring counterparts ?0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime ?0,linear/?0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation ?0,linear/?0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 \textless Z \textless 20, ?0,linear/?0,ring ? Z1.2±0.3, is weaker than the scaling prediction (?0,linear/?0,ring ? Z1.6±0.3) and the simulations (?0,linear/?0,ring ? Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem.$$nWe have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts ?0,linear to their ring counterparts ?0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime ?0,linear/?0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation ?0,linear/?0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 \textless Z \textless 20, ?0,linear/?0,ring ? Z1.2±0.3, is weaker than the scaling prediction (?0,linear/?0,ring ? Z1.6±0.3) and the simulations (?0,linear/?0,ring ? Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem.

### Full Text

### Duke Authors

### Cited Authors

- Pasquino, R; Vasilakopoulos, TC; Jeong, YC; Lee, H; Rogers, S; Sakellariou, G; Allgaier, J; Takano, A; Brás, AR; Chang, T; Gooßen, S; Pyckhout-Hintzen, W; Wischnewski, A; Hadjichristidis, N; Richter, D; Rubinstein, M; Vlassopoulos, D

### Published Date

- 2013

### Published In

### International Standard Serial Number (ISSN)

- 2161-1653

### Digital Object Identifier (DOI)

- 10.1021/mz400344e