Open AccessStress Relaxation in Symmetric Ring-Linear Polymer Blends at Low Ring Fractions
Author(s) -
Daniele Parisi,
Jungkyu Ahn,
Taihyun Chang,
Dimitris Vlassopoulos,
Michael Rubinstein
Publication year - 2020
Publication title -
macromolecules
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.994
H-Index - 313
eISSN - 1520-5835
pISSN - 0024-9297
DOI - 10.1021/acs.macromol.9b02536
Subject(s) - relaxation (psychology) , polymer , ring (chemistry) , materials science , viscoelasticity , volume fraction , viscosity , linear polymer , stress relaxation , polymer chemistry , linear molecular geometry , thermodynamics , chemistry , composite material , physics , molecule , organic chemistry , psychology , social psychology , creep
We combine linear viscoelastic measurements and modelling in order to explore the dynamics of blends of the same-molecular-weight ring and linear polymers in the regime of the low volume fraction (0.3 or lower) of the ring component. The stress relaxation modulus is affected by the constraint release (CR) of both rings and linear components due to the motion of linear chains. We develop a CR-based model of ring-linear blends that predicts the stress relaxation function in the low fraction regime of ring component in excellent agreement with experiments. Rings trapped by their entanglements with linear chains can only relax by linear-chain-induced constraint release, resulting in much slower relaxation of rings than of linear chains. The relative viscosityη ( ϕ R * ) / η Lof the blend with respect to the linear melt viscosity η L at ring overlap volume fraction ϕ R * increases proportionally to the square root of ring molecular weightM w , R. Our experimental results clearly demonstrate that it is possible to enhance the viscosity and simultaneously the structural relaxation time of linear polymer melts by adding a small fraction of ring polymers. These results not only provide fundamental insights into the physics of the CR process but also suggest ways to fine-tune the flow properties of linear polymers by means of adding rings.