scholarly journals Interrelation between mechanical response, strain field, and local free volume evolution in glassy polymers: Seeking the atomistic origin of post-yield softening

2018 ◽  
Vol 12 (1) ◽  
pp. 2-12 ◽  
Author(s):  
H. Goodarzi Hosseinabadi ◽  
R. Bagheri ◽  
T. Gigl ◽  
C. Hugenschmidt ◽  
D. Raps ◽  
...  
Keyword(s):  
Free Volume ◽  
Strain Field ◽  
Mechanical Response ◽  
Glassy Polymers

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

Influence of the loading rate on the indentation response of Ti-based metallic glass

2009 ◽  
Vol 24 (3) ◽  
pp. 918-925 ◽  
Author(s):  
J. Sort ◽  
J. Fornell ◽  
W. Li ◽  
S. Suriñach ◽  
M.D. Baró
Keyword(s):  
Metallic Glass ◽  
Free Volume ◽  
Mechanical Response ◽  
Loading Rate ◽  
Yield Criterion ◽  
Contact Stiffness ◽  
Strain Rates ◽  
Cohesive Stress ◽  
Crystalline Materials ◽  
Loading Rates

The mechanical behavior of Ti-based metallic glass has been investigated by means of indentation experiments at different loading rates. Contrary to many crystalline materials, an increase of the loading rate causes a reduction of hardness, i.e., a mechanical softening. This effect is ascribed to deformation-induced creation of excess free volume, which is more pronounced for higher strain rates. The decrease of hardness is accompanied with an increase of the contact stiffness and a reduction of the reduced elastic modulus. Finite element simulations reveal that the mechanical response of this material can be described using the Mohr-Coulomb yield criterion. The changes in the nanoindentation curves with the increase of loading rate are well reproduced by decreasing the value of the Mohr-Coulomb cohesive stress. This result is consistent with the presumed enhancement of free volume.

Changes In The Characteristics Of The Free Volume Of Glassy Polymers During Deformation And Relaxation.

1991 ◽  
Vol 227 ◽  
Author(s):  
M.I. Tsapovestsky ◽  
V.K. Lavrentiev ◽  
S.A. Tishin
Keyword(s):  
Dielectric Loss ◽  
Positron Annihilation ◽  
Free Volume ◽  
Small Angle ◽  
Mechanical Tests ◽  
Glassy Polymers ◽  
Volume Relaxation ◽  
X Ray ◽  
X Ray Scattering ◽  
Original Interpretation

ABSTRACTThe behavior of glassy polymers was studied with the aid of mechanical tests on the basis of free volume. Three types of experiments were carried out and interpreted using modern ideas about the structure of free volume. They were: 1. The study of changes in the total free volume occurring as a result of deformation (by measurement of density) 2. The study of micro voids and their changes on deformation using small angle X-ray scattering (SAXS) and positron annihilation 3. The study of mobile regions by the measurement of dielectric loss (using an original interpretation) during deformation. This allows several parts of the total free volume to be distinguished and investigated. A model for the free volume relaxation during deformation is proposed.

scholarly journals Coupled thermoviscoplasticity of glassy polymers in the logarithmic strain space based on the free volume theory

2011 ◽  
Vol 48 (13) ◽  
pp. 1799-1817 ◽  
Author(s):  
Christian Miehe ◽  
Joel Méndez Diez ◽  
Serdar Göktepe ◽  
Lisa-Marie Schänzel
Keyword(s):  
Free Volume ◽  
Glassy Polymers ◽  
Logarithmic Strain ◽  
Free Volume Theory ◽  
Strain Space

scholarly journals Methods for the calculation of occupied volumes in glassy polymers: The lattice integration and the monte carlo methods

2003 ◽  
Vol 1 (4) ◽  
pp. 402-426 ◽  
Author(s):  
E. Rozhkov ◽  
B. Schukin ◽  
I. Ronova
Keyword(s):  
Monte Carlo ◽  
Error Estimates ◽  
Free Volume ◽  
Monte Carlo Methods ◽  
Glassy Polymer ◽  
Monomer Unit ◽  
Glassy Polymers ◽  
Inert Gases ◽  
Improved Method ◽  
Accessible Volume

AbstractA new model for characterizing the free volume of a glassy polymer—gas systems is proposed. An improved method for the calculation of occupied volume per monomer unit was developed within the limits of this model. The model assumptions, error estimates and algorithm efficiencies are described. Using the example of polyvinyltrimethylsilane, it is shown that linear dependences of logarithms of the diffusion and the permeability coefficients on specific accessible volume for inert gases exist.

Stress-Strain Behavior of Rubber-Reinforced Glassy Polymers

1966 ◽  
Vol 39 (4) ◽  
pp. 1019-1029 ◽  
Author(s):  
Seymour Newman ◽  
Stephen Strella
Keyword(s):  
Stress Field ◽  
Free Volume ◽  
Large Scale ◽  
Rubber Particle ◽  
Cold Drawing ◽  
Glassy Polymers ◽  
Triaxial Stress ◽  
Strain Behavior ◽  
Rubber Phase ◽  
The Difference

Abstract The main objective of this work has been to develop some rational hypothesis for the toughness of rubber polyblends as defined by the energy to rupture in a tensile measurement. It is shown, both by induction and by direct experimental evidence, that the S/AN rigid phase yields and cold draws. It is thereby established that the toughness of a polyblend is a result of the large energy absorption involved in the cold drawing of the matrix. The presence of inherent flaws or cracks limits the strength and ductility of some glassy polymers, whereas others are known to cold-draw. It is believed, therefore, that the rubber phase in a polyblend acts principally to induce a yielding in the S/AN matrix. There are at least two factors which contribute to this yielding. (a) By limiting the crack growth, the rubber phase effectively strengthens the rigid phase, prevents premature fracture, and permits yielding. In this connection, it is believed that under a tensile strain, the difference in the Poisson's ratio of the rubber and matrix phases results in a triaxial stress field in the environment of the rubber particle. Under such a triaxial stress field, the rubber particle possesses a strength which is greater than in tension and which is sufficient to prevent crack propagation. (b) Secondly, the triaxial field will result in an increase in the free volume of the SAN matrix adjacent to the rubber particle. This, combined with other factors, causes an increase in free volume sufficient to lower the glass transition temperature of S/AN to the point where large-scale molecular motion or cold drawing is further favored.

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