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A predictive model for the effects of thermal history on the mechanical behavior of amorphous polymers
Author(s) -
Shay R. M.,
Caruthers J. M.
Publication year - 1990
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760302003
Subject(s) - materials science , viscoelasticity , amorphous solid , constitutive equation , polymer , thermodynamics , isothermal process , composite material , yield (engineering) , nonlinear system , physics , crystallography , chemistry , quantum mechanics , finite element method
The effects of thermal history during formation on the mechanical behavior of amorphous polymer solids must be part of a constitutive description for polymers in order to enable efficient design of manufacturing processes. A nonlinear, thermoviscoelastic constitutive equation for amorphous polymers has been previously derived via the rational thermodynamics framework, where the dissipation is assumed to occur on a material timescale that is controlled by the non‐equilibrium entropy, In this paper we report on the predictions of this constitutive equation for poly(vlnyl acetate). The material properties required by the constitutive model were determined for poly(vinyl acetate) from PVT and linear viscoelastic shear and bulk moduli measurements. Predictions of specific volumes during isobarfc cooling from the rubber and nonlinear uniaxial stress‐strain curves just below T g are in reasonable agreement with experimental data. The model predicts that samples cooled below T g and then isothermally annealed for specified times will exhibit yield stresses that increase with Increasing annealing time, as well as the familiar effects of changes in temperature and strain rate on the uniaxial stress‐strain and yield behavior. Shortcomings and potential improvements in the model are discussed.