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A predictive model for the effects of thermal history on the mechanical behavior of amorphous polymers

A predictive model for the effects of thermal history on the mechanical behavior of amorphous... 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 Tg are in reasonable agreement with experimental data. The model predicts that samples cooled below Tg 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. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Polymer Engineering & Science Wiley

A predictive model for the effects of thermal history on the mechanical behavior of amorphous polymers

Shay, R. M.; Caruthers, J. M.
Polymer Engineering & Science , Volume 30 (20) – Oct 1, 1990
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References (25)

Publisher
Wiley
Copyright
Copyright © 1990 Society of Plastics Engineers
ISSN
0032-3888
eISSN
1548-2634
DOI
10.1002/pen.760302003
Publisher site
See Article on Publisher Site

Abstract

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 Tg are in reasonable agreement with experimental data. The model predicts that samples cooled below Tg 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.

Journal

Polymer Engineering & Science – Wiley

Published: Oct 1, 1990

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