Elasticity of Soft Polymers. Constant-Stress Elongation Tests

1952 ◽  
Vol 25 (1) ◽  
pp. 56-70
Author(s):  
C. A. Dahlquist ◽  
J. O. Hendricks ◽  
N. W. Taylor
Keyword(s):  
Time Dependence ◽  
Viscous Flow ◽  
Empirical Equation ◽  
Relaxation Times ◽  
Polymeric Materials ◽  
Constant Stress ◽  
Elastic Behavior ◽  
Total Deformation ◽  
Test Conditions ◽  
Elastic Processes

Abstract The elastic properties of polymeric materials which are too soft to test on conventional stress-strain machines can be obtained by elongation at constant stress. A simple apparatus has been developed for maintaining constant stress during elongation. Data illustrate the time dependence of the elastic behavior of polymeric materials and demonstrate the usefulness of the constant-stress method in the evaluation of this time dependence. The constant-stress method is useful in the evaluation of plasticizers for gum rubbers. Because of the difficulty of separating highly delayed elastic elongation from viscous flow, the method has not been found practical as a tool for measurement of viscosity in the solid state. However, under most test conditions, viscous flow has been a negligible fraction of the total deformation. Several terms for delayed elasticity are required to fit an empirical equation to the elongation-time curves, and it seems probable that these terms are only an approximation of a very large number of delayed elastic processes having different relaxation times.

Time Dependances of the Resistance Coefficients of Polymeric Materials

INEOS OPEN ◽  
2020 ◽  
Vol 3 ◽  
Author(s):  
A. V. Matseevich ◽  
◽  
A. A. Askadskii ◽  
Keyword(s):  
Time Dependence ◽  
Physical Mechanism ◽  
Polymeric Materials ◽  
Resistance Coefficient ◽  
Constant Stress ◽  
Time To Rupture ◽  
Structure Sensitive ◽  
Material Durability ◽  
Resistance Coefficients ◽  
Extremal Character

One of the possible approaches to the analysis of a physical mechanism of time dependence for the resistance coefficients of materials is suggested. The material durability at the constant stress is described using the Zhurkov and Gul' equations and the durability at the alternating stress—using the Bailey criterion. The low strains lead to structuring of a material that is reflected in a reduction of the structure-sensitive coefficient in these equations. This affords 20% increase in the durability. The dependence of the resistance coefficient assumes an extremal character; the maximum is observed at the time to rupture lg tr ≈ 2 (s).

Relaxation Time Spectrum, Elasticity, and Viscosity of Rubber. I

1954 ◽  
Vol 27 (1) ◽  
pp. 36-54 ◽  
Author(s):  
W. Kuhn ◽  
O. Künzle ◽  
A. Preissmann
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Time Spectrum ◽  
Test Sample ◽  
Elastic Behavior ◽  
Relaxation Processes ◽  
Relaxation Time Spectrum ◽  
Restoring Force ◽  
Constant Length ◽  
Rapid Deformation

Abstract By rapid deformation of a medium in which linear molecules are present, various changes are produced simultaneously in the latter. These changes are more or less independent of one another, and can release independently and totally or partially by rearrangement of valence distances and valence angles in the chain molecules. By virtue of such relaxation processes, a portion of the stress originating in the rapid deformation disappears, with a changing time requirement for the various portions. A relaxation time spectrum is thus formed. The relaxation time spectrum consists of a finite number of restoring force mechanisms with proper relaxation times or of a continuous spectrum. Both the creep curves (the dependence of the length of a body on time at constant load), and stress relaxation (decay of the stress observed in test sample kept at constant length after rapid deformation), as well as the total visco-elastic behavior, especially the behavior at constant periodic deformation of the test sample, are determined by the relaxation time spectrum. The appropriate Quantitative relationships were derived.

Multiplicity of dielectric-relaxation times of dispersed ice microcrystals. Time dependence

1987 ◽  
Vol 9 (7) ◽  
pp. 815-828 ◽  
Author(s):  
P. Pissis ◽  
L. Apekis ◽  
C. Christodoulides
Keyword(s):  
Time Dependence ◽  
Dielectric Relaxation ◽  
Relaxation Times

Behavior models of concrete. General theory of degradation

2019 ◽  
Author(s):  
Андрей Варламов ◽  
Andrey Varlamov ◽  
Владимир Римшин ◽  
Vladimir Rimshin
Keyword(s):  
Composite Material ◽  
General Theory ◽  
Experimental Studies ◽  
Polymeric Materials ◽  
Elastic Behavior ◽  
Industrial Building ◽  
Relative Deformation ◽  
Energy Potential ◽  
Wood Structures ◽  
Behavior Models

Is it possible eternal existence, and there will inevitably destruction? The monograph for the first time describes the General theory of degradation. The theory is described in its practical application to multifunctional composite concrete and reinforced concrete structures. As you know, the basis of these structures is concrete. The monograph is composed of two parts. The first part of the monograph deals with various modern approaches to modeling the behavior of concrete. Concrete is considered as the most important industrial building material. A comprehensive analysis of the behavior of concrete as a composite material is performed. Structural, technological, statistical and phenomenological models of its behavior are reviewed and considered. Describes the modern theoretical model of structural concrete, including model structural mechanics and fracture mechanics, theory of similarity and theory of loose bodies. Reviewed various proposals for how to transform the graphs of the behavior of concrete under various conditions. The results of our own experimental studies are presented. The information base of concrete behavior is obtained and described. Examples of the processed results in the database. On the basis of factor, canonical and regression analyses statistical models of concrete behavior are proposed. Structural analysis of concrete as a composite material allowed to develop models of its elastic behavior. The influence of concrete composite structure on its deformation and strength is revealed. The effect of cracks on the relative deformation of concrete is shown. In the second part of the monograph describes the main provisions of the theory of degradation as a General theory of destruction of the object. The relative independence of energy and time in the destruction of objects is revealed. A new characteristic of the object – the energy potential-is proposed. The connection of the theory of degradation with durability of various objects is shown. For concrete, two main forms of constructing a model of its behavior are identified. On the basis of the developed models of concrete behavior, diagrams of standard tests of concrete and transformed diagrams of its behavior in time are constructed. The possibility of using the developed models in relation to other materials and structures: steel, pipe concrete, wood, structures made of polymeric materials.

The Effect of Structural Relaxation on the Diffusion of Au in Amorphous Pd80Si20

1992 ◽  
Vol 279 ◽  
Author(s):  
A. V. Wagner ◽  
F. Spaepen
Keyword(s):  
Time Dependence ◽  
Viscous Flow ◽  
Concentration Profile ◽  
Structural Relaxation ◽  
Rutherford Backscattering Spectrometry ◽  
New Method ◽  
Relaxation Model ◽  
Sputter Deposited ◽  
Kinetics Of ◽  
Short Times

ABSTRACTThe diffusivity of Au in sputter-deposited amorphous Pd80Si20 has been measured by Rutherford backscattering spectrometry (RBS) between 275°C and 380°C. A new method based on scaling of the evolution of the variance of the concentration profile was used to analyze the data. The diffusivity was found to be independent of the Au concentration below 3 at.%. Structural relaxation causes a time dependence that is evident at short times. The kinetics of this relaxation can be described by the bimolecular relaxation model used in the analysis of viscous flow.

Influence of Test Conditions and Couple Materials on Frictional Characteristic of Polymeric Materials

2011 ◽  
Vol 306-307 ◽  
pp. 684-687
Author(s):  
Li Xiao Jia ◽  
Yong Zhen Zhang ◽  
Yong Ping Niu ◽  
San Ming Du ◽  
Jian Li
Keyword(s):  
Friction Coefficient ◽  
Polymeric Material ◽  
Polymeric Materials ◽  
Friction Characteristic ◽  
Test Conditions ◽  
Frictional Characteristic

Frictional characteristic of three kinds of polymeric material was studied by Mark II slipmeter under the condition of different couple materials and test conditions in order to understand the frictional mechanism of people’s walking deeply and decrease the probability of accidents caused by slips and falls. The results indicate that test conditions and couple materials influent friction characteristic of polymeric materials but the influence of test conditions is more significant. In the three test conditions, the friction coefficient of dry condition is highest and that of oil condition is lowest. The friction coefficient of polymeric materials on different floor samples had different trend indicated that there was interaction between shoe sole samples and floor samples.

scholarly journals Dielectric Relaxation of Mixtures of N-Methylacetamide and N,N-Dimethylformamide Solved in Benzene Using Microwave Absorption Data

2006 ◽  
Vol 61 (3-4) ◽  
pp. 197-204
Author(s):  
Raman Kumar ◽  
V. S. Rangra ◽  
D. R. Sharma ◽  
N. Thakur ◽  
N. S. Negi
Keyword(s):  
Dielectric Relaxation ◽  
Viscous Flow ◽  
Relaxation Process ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Single Frequency ◽  
Absorption Data ◽  
Dielectric Relaxation Process ◽  
Energy Parameters ◽  
Microwave Techniques

The dielectric relaxation times τ and dipole moments μ of N-methylacetamide (NMA) mixed with N,N-dimethylformamide (DMF) in benzene solutions have been obtained using standard standing wave microwave techniques and Gopala Krishna’s single frequency (9.90 GHz) concentration variational method at 25, 30, 35, and 40 ◦C. The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of mixtures with equal amounts of NMA and DMF have been calculated and compared with the corresponding energy parameters (ΔHη , ΔFη , ΔSη ) for the viscous flow. On the basis of the observations it is found that the dielectric relaxation process can be treated as a rate process like the viscous flow. Solute-solute and solute-solvent types of the molecular associations have been predicted

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