Okereke, Michael I. ORCID: 0000-0002-2104-012X and Akpoyomare, Ambrose I. (2019) Two-process constitutive model for semicrystalline polymers across a wide range of strain rates. Polymer, 183:121818. ISSN 0032-3861 (doi:https://doi.org/10.1016/j.polymer.2019.121818)

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Abstract

The presence of crystalline and amorphous phases in semicrystalline polymers presents interesting constitutive modelling challenges. In this study, a physically based, three-dimensional constitutive model has been developed for simulating a wide range of features observed in deformation and processing of semicrystalline polymers. The proposed model combines into one constitutive model such features as: multiple viscoelastic relaxation processes, very wide strain-rate range, temperature-dependence, adiabatic heating, structural rejuvenation; in addition to it being applied to a semicrystalline polymer. The constitutive mathematics is based on a one-process glass-rubber model for amorphous polymers. It adapts that model to semicrystalline polymers by extending it to two relaxation processes: one associated with the glass transition of the mobile amorphous phase; the other associated with relaxation of the crystalline fraction and its associated rigid amorphous phase. In particular, two dominant processes were identified: the α-process and the β-process. The model has been implemented numerically into a commercial finite element code through a user-defined material subroutine (UMAT). The model has been validated against compression test results carried out on polypropylene. Also, the model predicts very well the experimentally observed nonlinear rate-dependent response and post-yield de-ageing of polypropylene.

Item Type:	Article
Uncontrolled Keywords:	semicrystalline polymers, polypropylene, constitutive modeling, nonlinear rate-dependent response
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Engineering (ENG)
Last Modified:	27 Sep 2020 01:38
URI:	http://gala.gre.ac.uk/id/eprint/25456

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