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A constitutive model for block-copolymers based on effective temperature

Das, Sanhita and Roy, Debasish (2019) A constitutive model for block-copolymers based on effective temperature. In: INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 161 .

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Official URL: htpps://dx.doi.org/10.1016/j.ijmecsci.2019.105082


Phase segregated copolymers such as elastomeric copolymers find myriad applications especially in impact resistant structures. When domains with varying relaxation characteristics are present, these polymers exhibit thermorheologically complex behaviour. The multiple relaxation processes are herein captured using the effective temperature based thermodynamics, used extensively in modelling thermo-mechanical response of metals and polymers. Specifically, we use two slowly evolving configurational subsystems and a fast evolving kinetic-vibration (K-V) subsystem. The two configurational subsystems represent the inter-molecular and intra-molecular meso-scale configurational transformations occurring within the two domains. The K-V subsystem represents the faster atomic vibrations. The configurational subsystems are weakly coupled with the K-V through heat exchange which accounts for structural relaxations of the individual domains towards the equilibrium microstructure. Based on this, we are able to capture strain rate dependence and strain induced softening of these materials under cyclic loads. In comparison with the existing formulations for such copolymers, ours is perhaps a more transparent approach, as it uses quantities such as volume fraction, glass transition temperatures of individual domains as material parameters. Indeed, our formulation could be readily adapted for non-elastomeric copolymers. It should also be potentially useful as a design tool for copolymers with increased glass transition range.

Item Type: Journal Article
Additional Information: copy right of this article belong to PERGAMON-ELSEVIER SCIENCE LTD
Keywords: Effective-temperature; Polymer; Glass transition; Viscoelasticity; Structural relaxation; Effective temperature; Physical ageing; Mechanical rejuvenation; Polyurea; Copolymer; Slow indentation; Thermoplastic elastomers
Department/Centre: Division of Mechanical Sciences > Civil Engineering
Date Deposited: 18 Dec 2019 10:57
Last Modified: 18 Dec 2019 10:57
URI: http://eprints.iisc.ac.in/id/eprint/64071

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