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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/5422
Title: A constitutive model for thermoplastics based on two temperatures
Authors: Das S.
Roy Chowdhury, Shubhankar
Roy D.
Published in: European Journal of Mechanics, A/Solids
Abstract: Posed within a two-temperature thermodynamic framework, our aim is to propose a unified glass-rubber constitutive model for thermo-rheologically simple thermoplastic polymers. This modelling set-up usually applies to phenomena wherein sub-macroscopic processes involving different time scales occur and accordingly the thermodynamic system may be interpreted as comprising of two subsystems. The configurational subsystem contains the slower states, while the kinetic-vibrational subsystem comprises of the faster moving states. The two subsystems fail to equilibrate within experimental timescales in the glassy regime (low temperature or high strain rate) due to low structural relaxation rates. As transition to the rubbery regime commences at temperatures higher than glass transition or at sufficiently low loading rates, the two subsystems equilibrate within microscopic timescales. The model exploits physically inspired prescriptions for the free energies due to different underlying mechanisms - elastic stretching, localised shear transformations and intra-molecular straightening of chains. A simple temperature dependent formulation for structural relaxation in terms of heat transfer between the subsystems is used to capture transition between these mechanisms. The model is then validated against experimental results of uniaxial compression tests for various strain rates and temperatures establishing its ability to seamlessly transit between the glassy and rubbery regimes. Also demonstrated is the model's efficacy in capturing the key features of physical ageing and mechanical rejuvenation. ¬© 2018 Elsevier Masson SAS
Citation: European Journal of Mechanics, A/Solids(2018), 72(): 440-451
URI: https://doi.org/10.1016/j.euromechsol.2018.06.010
http://repository.iitr.ac.in/handle/123456789/5422
Issue Date: 2018
Publisher: Elsevier Ltd
Keywords: Effective temperature
Glass transition
Mechanical rejuvenation
Physical ageing
Polymer
Secondary hardening
Strain softening
Structural relaxation
Two temperature thermodynamics
Viscoelasticity
ISSN: 9977538
Author Scopus IDs: 57213459744
56818427600
7402439420
Author Affiliations: Das, S., Computational Mechanics Lab., Department of Civil Engineering, Indian Institute of Science, Bangalore, 560012, India
Roy Chowdhury, S., Computational Mechanics Lab., Department of Civil Engineering, Indian Institute of Science, Bangalore, 56001
Corresponding Author: Roy, D.; Computational Mechanics Lab., Department of Civil Engineering, Indian Institute of ScienceIndia; email: royd@iisc.ac.in
Appears in Collections:Journal Publications [CE]

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