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Viscosity of ring polymer melts.


ABSTRACT: 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 η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as function of the number of entanglements Z. In the unentangled regime η0,linear0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear0,ring=2. In the entanglement regime, the Z-dependence of rings 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 1η0,linear0,ring ~ Z1.2±0.3, is weaker than the scaling prediction (η0,linear0,ring ~ Z1.6±0.3 ) and the simulations (η0,linear0,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.

SUBMITTER: Pasquino R 

PROVIDER: S-EPMC4517619 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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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 <i>η<sub>0,linear</sub></i> to their ring counterparts <i>η<sub>0,ring</sub></i> at isofrictional conditions is discussed as function of the number of entanglements <i>Z</i>. In the unentangled regime <i>η<sub>0,linear</sub>/η<sub>0,ring</sub></i> is virtually constant, consistent with the ea  ...[more]

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