A new pressurizable dilatometer for measuring the time-dependent bulk modulus and pressure-volume-temperature properties of polymeric materials

2009 ◽  
Vol 80 (5) ◽  
pp. 053903 ◽  
Author(s):  
Yan Meng ◽  
Paul Bernazzani ◽  
Paul A. O’Connell ◽  
Gregory B. McKenna ◽  
Sindee L. Simon
Keyword(s):  
Bulk Modulus ◽  
Polymeric Materials ◽  
Time Dependent

Thermoelastic Constitutive Equations for Chemically Hardening Materials

1974 ◽  
Vol 41 (3) ◽  
pp. 652-657 ◽  
Author(s):  
Bernard W. Shaffer ◽  
Myron Levitsky
Keyword(s):  
Bulk Modulus ◽  
Strain Rate ◽  
Chemical Reaction ◽  
Constitutive Equations ◽  
Strain Energy ◽  
Elastic Solid ◽  
Time Dependent ◽  
Component Model ◽  
Two Component ◽  
Potential Applications

Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.

Interconversions between linear viscoelastic functions with a time-dependent bulk modulus

2017 ◽  
Vol 23 (6) ◽  
pp. 879-895 ◽  
Author(s):  
Dao-Long Chen ◽  
Tz-Cheng Chiu ◽  
Tei-Chen Chen ◽  
Ping-Feng Yang ◽  
Sheng-Rui Jian
Keyword(s):  
Bulk Modulus ◽  
Relaxation Modulus ◽  
Time Dependent ◽  
Reasonable Assumption ◽  
Prony Series ◽  
Relaxation Rates ◽  
Unknown Parameters ◽  
Linear Viscoelastic ◽  
Shear Relaxation ◽  
Increasing Function

The interconversion relations for viscoelastic functions are derived with the consideration of the time-dependent bulk modulus, K( t), for both traditional and fractional Prony series representations of viscoelasticity. The application of these relations is to replace the fitting parameters of Young’s relaxation modulus, E( t), by the unknown parameters of K( t) and the known parameters of the shear relaxation modulus, G( t), and to fit the E( t) to the experimental data for obtaining the parameters of K( t). The fitting results show that only two experiments for measuring the viscoelastic functions of an isotropic material are not enough to determine the other viscoelastic functions. However, if we consider the relaxation rates of K( t) and G( t), we may conclude that the constant bulk modulus is a more reasonable assumption, and the corresponding Poisson’s ratio, ν( t), is a monotonic-increasing function.

scholarly journals Micromechanics of creep and relaxation of wood. A review COST Action E35 2004–2008: Wood machining – micromechanics and fracture

Holzforschung ◽  
2009 ◽  
Vol 63 (2) ◽  
Author(s):  
Parviz Navi ◽  
Stefanie Stanzl-Tschegg
Keyword(s):  
Mechanical Response ◽  
Molecular Level ◽  
Polymeric Materials ◽  
Climatic Conditions ◽  
Time Dependent ◽  
Viscoelastic Behaviour ◽  
Single Fibres ◽  
Time Dependent Behaviour ◽  
Wood Machining ◽  
Dependent Behaviour

Abstract Wood, like all polymeric materials, shows viscoelastic behaviour. The time dependent behaviour of wood depends on material anisotropy, temperature, moisture and stresses. To predict the behaviour of wood, numerous mathematical models have been developed largely relying on experimental results. In this paper, time dependent viscoelastic behaviour of wood is reviewed under constant and cyclic climatic conditions, separately. More emphasis is given on results obtained in recent years on the behaviour of thin wood tissues, single fibres, thermo-viscoelasticity of wood, influence of hemicelluloses and the modelling of the effect of transient moisture at the molecular level on the mechanical response.

Nonlinear Viscoelastic Constitutive Equations for Composites Based on Work Potentials

1994 ◽  
Vol 47 (6S) ◽  
pp. S269-S275 ◽  
Author(s):  
R. A. Schapery
Keyword(s):  
Constitutive Equations ◽  
Viscoelastic Behavior ◽  
Polymeric Materials ◽  
Time Dependent ◽  
Inelastic Behavior ◽  
Nonlinear Viscoelastic ◽  
Viscoelastic Effects ◽  
Residual Strains ◽  
Viscoelastic Composites ◽  
Independent Behavior

Constitutive equations for nonlinear viscoelastic composites are discussed. The effects of time-independent inelastic behavior, microcracking and time-dependent residual strains are considered along with the viscoelastic effects that are traditionally associated with the behavior of monolithic and reinforced polymeric materials. Time-independent behavior is discussed first, in which the experimentally observed insensitivity of mechanical work to deformation or load paths is used as the basis for a simplified constitutive model. This representation is then modified to account for time- or rate-effects due to microcrack-like evolution laws. Effects due to broad spectrum nonlinear, viscoelastic behavior of the polymer matrix are reviewed and then used in a generalized constitutive equation with both time-independent and time-dependent effects. Emphasis of this paper is on a thermodynamically-based phenomenological description of deformation response and the use of simplifications based on experimental observations. However, there is a limited discussion of physical mechanisms for nonlinear time-dependent behavior.

Effect of van der Waals Interaction Strength and Nanocluster Size on the Dynamical and Mechanical Properties of 1,4-cis-polybutadiene Melts

2012 ◽  
Vol 1424 ◽  
Author(s):  
Canan Atilgan ◽  
Ibrahim Inanc ◽  
Ali Rana Atilgan
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Bulk Modulus ◽  
Residence Time ◽  
Van Der Waals ◽  
Interaction Strength ◽  
Polymeric Materials ◽  
Van Der Waals Interactions ◽  
Increasing Trend ◽  
Dynamics Simulations

ABSTRACTUsing molecular dynamics simulations, we have investigated the effect of embedding nanoclusters of radius 3-7 Å on the dynamical and mechanical properties of 1,4-cispolybutadiene melts. To see the effect of polymer-nanocluster interaction strength on the bulk modulus, the van der Waals interactions (vdW) between the polymer chain and nanocluster have been varied from weak to very stong while keeping polymer-polymer and nanoclusternanocluster interactions constant. The modulus depends on the interaction strength, but not on nanocluster size. Residence time of chains on the surface of the nanocluster (τr) has an increasing trend that reaches to a plateau as the vdW strength is increased. τr also doubles from 100 ps to 200 ps as the nanocluster size is increased from 3 to 7 Å. Our findings give clues on how the properties of polymeric materials may be controlled by nanoparticles of different chemistry and size.

scholarly journals Viscous and Failure Mechanisms in Polymer Networks: A Theoretical Micromechanical Approach

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1576 ◽  
Author(s):  
Roberto Brighenti ◽  
Federico Artoni ◽  
Mattia Pancrazio Cosma
Keyword(s):  
Failure Mechanisms ◽  
Polymer Networks ◽  
Polymeric Materials ◽  
Time Dependent ◽  
Main Field ◽  
Micro Scale ◽  
Bond Scission ◽  
Reliable Model ◽  
Micromechanical Approach ◽  
Physically Based

Polymeric materials typically present a complex response to mechanical actions; in fact, their behavior is often characterized by viscous time-dependent phenomena due to the network rearrangement and damage induced by chains’ bond scission, chains sliding, chains uncoiling, etc. A simple yet reliable model—possibly formulated on the basis of few physically-based parameters—accounting for the main micro-scale micromechanisms taking place in such a class of materials is required to properly describe their response. In the present paper, we propose a theoretical micromechanical approach rooted in the network’s chains statistics which allows us to account for the time-dependent response and for the chains failure of polymer networks through a micromechanics formulation. The model is up-scaled to the mesoscale level by integrating the main field quantities over the so-called ‘chains configuration space’. After presenting the relevant theory, its reliability is verified through the analysis of some representative tests, and some final considerations are drawn.

The Resolution and Contrast in Biological Sections Determined by Inelastic and Elastic Scattering

1973 ◽  
Vol 31 ◽  
pp. 224-225
Author(s):  
D. L. Misell
Keyword(s):  
Electron Microscopy ◽  
Adverse Effect ◽  
Elastic Scattering ◽  
Inelastic Scattering ◽  
Amorphous Carbon ◽  
Polymeric Materials ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Quantitative Estimates ◽  
Elastic Ratio

In the electron microscopy of biological sections the adverse effect of chromatic aberration on image resolution is well known. In this paper calculations are presented for the inelastic and elastic image intensities using a wave-optical formulation. Quantitative estimates of the deterioration in image resolution as a result of chromatic aberration are presented as an alternative to geometric calculations. The predominance of inelastic scattering in the unstained biological and polymeric materials is shown by the inelastic to elastic ratio, I/E, within an objective aperture of 0.005 rad for amorphous carbon of a thickness, t=50nm, typical of biological sections; E=200keV, I/E=16.

Application Of Electron Microscopy To Automotive Finish Defect Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 258-259
Author(s):  
Martin J. Mahon ◽  
Patrick W. Keating ◽  
John T. McLaughlin
Keyword(s):  
Electron Microscopy ◽  
Zero Tolerance ◽  
Polymeric Materials ◽  
Plant Management ◽  
Defect Analysis ◽  
X Ray ◽  
Root Cause ◽  
Cutting Out ◽  
Foreign Materials ◽  
Automotive Finish

Coatings are applied to appliances, instruments and automobiles for a variety of reasons including corrosion protection and enhancement of market value. Automobile finishes are a highly complex blend of polymeric materials which have a definite impact on the eventual ability of a car to sell. Consumers report that the gloss of the finish is one of the major items they look for in an automobile.With the finish being such an important part of the automobile, there is a zero tolerance for paint defects by auto assembly plant management. Owing to the increased complexity of the paint matrix and its inability to be “forgiving” when foreign materials are introduced into a newly applied finish, the analysis of paint defects has taken on unparalleled importance. Scanning electron microscopy with its attendant x-ray analysis capability is the premier method of examining defects and attempting to identify their root cause.Defects are normally examined by cutting out a coupon sized portion of the autobody and viewing in an SEM at various angles.

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