A Model for Mechanically Induced Densification of Glassy Polymers

1999 ◽  
Vol 66 (3) ◽  
pp. 702-708 ◽  
Author(s):  
A. D. Drozdov
Keyword(s):  
Composite Material ◽  
Free Volume ◽  
Constitutive Equations ◽  
Specific Volume ◽  
Amorphous Polymer ◽  
Glassy Polymers ◽  
Viscoelastic Response ◽  
Stress Strain ◽  
Small Strains ◽  
Temporary Network

Constitutive equations are derived for the isothermal viscoelastic response of glassy polymers at small strains. An amorphous polymer is modeled as a composite material consisting of a temporary network of long chains, immobile voids, and free volume gas diffusing through the network. The model is applied to analyze stress-induced densification of polymers in tensile and compressive relaxation tests. It is demonstrated that the stress-strain relations adequately predict a decrease in the specific volume observed in uniaxial experiments on polycarbonate.

Elasto-viscoplastic constitutive equations for the description of glassy polymers behavior at constant strain rate

2006 ◽  
Vol 129 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Fahmi Zaïri ◽  
Moussa Naït-Abdelaziz ◽  
Krzysztof Woznica ◽  
Jean-Michel Gloaguen
Keyword(s):  
Constitutive Equations ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Glassy Polymers ◽  
Uniaxial Tensile ◽  
Model Parameters ◽  
Strain Rates ◽  
State Variable ◽  
Rubber Toughened ◽  
Compressive Tests

In this study, a modelization of the viscoplastic behavior of amorphous polymers is proposed, from an approach originally developed for metal behavior at high temperature, in which state variable constitutive equations have been modified. A procedure for the identification of model parameters is developed through the use of experimental data from both uniaxial compressive tests extracted from the literature and uniaxial tensile tests performed in this study across a variety of strain rates. The numerical algorithm shows that the predictions of this model well describe qualitatively and quantitatively the intrinsic softening immediately after yielding and the subsequent progressive orientational hardening corresponding to the response of two polymers, amorphous polyethylene terephthalate and rubber toughened polymethyl methacrylate.

Role of free volume in molecular mobility and performance of glassy polymers for corrosion-protective coatings

2020 ◽  
Vol 55 (2) ◽  
pp. 145-158
Author(s):  
A. J. Hill ◽  
A. W. Thornton ◽  
R. H. J. Hannink ◽  
J. D. Moon ◽  
B. D. Freeman
Keyword(s):  
Free Volume ◽  
Molecular Mobility ◽  
Protective Coatings ◽  
Glassy Polymers ◽  
And Performance
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