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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 23 Oct 2019 21:13:35 GMT2019-10-23T21:13:35ZA torsion test for the study of the large deformation recovery of shape memory polymers
http://hdl.handle.net/10985/6560
A torsion test for the study of the large deformation recovery of shape memory polymers
DIANI, Julie; FREDY, Carole; GILORMINI, Pierre; MERCKEL, Yannick; REGNIER, Gilles; ROUSSEAU, Ingrid
A torsion device was designed and built for testing the shape fixity and shape recovery of shape memory polymers at large deformation. A simple thermal chamber was used to regulate the thermal environment during testing and a CCD camera was used for recording the deformation. Such a torsion testing system provided a quantitative estimate of the kinematics and kinetics of shape recovery for samples submitted to large deformations at moderate strains that are more likely expected in actual shape memory applications. In addition, such measurements are complementary to those obtained from large strain uniaxial tension tests usually run for during traditional shape memory effect characterization. As a result, the torsional shape memory testing device and testing method described is expected to contribute building complementary data for the thermomechanical modeling of shape memory polymers.
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10985/65602011-01-01T00:00:00ZDIANI, JulieFREDY, CaroleGILORMINI, PierreMERCKEL, YannickREGNIER, GillesROUSSEAU, IngridA torsion device was designed and built for testing the shape fixity and shape recovery of shape memory polymers at large deformation. A simple thermal chamber was used to regulate the thermal environment during testing and a CCD camera was used for recording the deformation. Such a torsion testing system provided a quantitative estimate of the kinematics and kinetics of shape recovery for samples submitted to large deformations at moderate strains that are more likely expected in actual shape memory applications. In addition, such measurements are complementary to those obtained from large strain uniaxial tension tests usually run for during traditional shape memory effect characterization. As a result, the torsional shape memory testing device and testing method described is expected to contribute building complementary data for the thermomechanical modeling of shape memory polymers.An experimental and analytical study of the elasticity of model polyurethane networks crosslinked by tri- and quadriisocyanate
http://hdl.handle.net/10985/6814
An experimental and analytical study of the elasticity of model polyurethane networks crosslinked by tri- and quadriisocyanate
FAYOLLE, Bruno; GILORMINI, Pierre; DIANI, Julie
Polyurethane networks have been prepared from a mix of tri- and quadriisocyanate and from two types of diols, polyether-based (with molar masses of 1,000, 2,000, and 4,000 g/mol) and polyester-based (1,035 g/mol). The weight fraction of sol has been measured, as well as the elastic shear modulus of the gels. It has been found that the statistical theory of network formation predicts a weight fraction of sol in agreement with the experimental results, but its standard combination with the theory of rubber elasticity disagrees significantly with the elastic modulus measured. This suggests a discrepancy between theory and experiment in terms of elastically active chains. In contrast, the assumption that all nodes in the gel, or even in the system, are elastically active gives much better predictions for the system considered.
The original publication is available at www.springerlink.com : http://link.springer.com/article/10.1007%2Fs00396-009-2145-6?LI=true
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10985/68142010-01-01T00:00:00ZFAYOLLE, BrunoGILORMINI, PierreDIANI, JuliePolyurethane networks have been prepared from a mix of tri- and quadriisocyanate and from two types of diols, polyether-based (with molar masses of 1,000, 2,000, and 4,000 g/mol) and polyester-based (1,035 g/mol). The weight fraction of sol has been measured, as well as the elastic shear modulus of the gels. It has been found that the statistical theory of network formation predicts a weight fraction of sol in agreement with the experimental results, but its standard combination with the theory of rubber elasticity disagrees significantly with the elastic modulus measured. This suggests a discrepancy between theory and experiment in terms of elastically active chains. In contrast, the assumption that all nodes in the gel, or even in the system, are elastically active gives much better predictions for the system considered.An introduction to the statistical theory of polymer network formation
http://hdl.handle.net/10985/6886
An introduction to the statistical theory of polymer network formation
GILORMINI, Pierre
A short but detailed introduction to the statistical theory of polymer network formation is given, including gel formation, gel structure, and sol fraction. Focus is put on the use of probability generating functions, and results that are of interest for polymer network elasticity are emphasized. Detailed derivations are supplied, and a simple 6-step procedure is provided, so that the reader is able to adapt and apply the theory to his own chemical systems, even if examples are given on polyurethanes essentially.
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10985/68862011-01-01T00:00:00ZGILORMINI, PierreA short but detailed introduction to the statistical theory of polymer network formation is given, including gel formation, gel structure, and sol fraction. Focus is put on the use of probability generating functions, and results that are of interest for polymer network elasticity are emphasized. Detailed derivations are supplied, and a simple 6-step procedure is provided, so that the reader is able to adapt and apply the theory to his own chemical systems, even if examples are given on polyurethanes essentially.Charcaterization of the Mullins effect of carbon-black filled rubbers
http://hdl.handle.net/10985/6804
Charcaterization of the Mullins effect of carbon-black filled rubbers
MERCKEL, Yannick; DIANI, Julie; BRIEU, Mathias; GILORMINI, Pierre; CAILLARD, Julien
Several carbon-black filled styrene-butadiene rubbers showed different sensibilities to the Mullins softening when submitted to cyclic uniaxial tension. In order to quantify this softening, a damage parameter was introduced. It is defined by using a classic damage approach and can be estimated by using either the strain amplification factor method or the tangent modulus at zero stress. The proposed parameter is used to study the effects of crosslink density and filler amount on the Mullins softening. The latter is shown to remain unaffected by a change of crosslink density and to increase with an increase of filler amount. The damage parameter exhibits mere linear dependences on the maximum Hencky strain applied and on the filler volume fraction. A simple linear expression is given finally to predict the Mullins softening of filled rubbers. The parameter also provides an objective analysis for the Mullins softening that supports comments on a better understanding of this effect.
Publisher version : http://rubberchemtechnol.org/doi/abs/10.5254/1.3592294?journalCode=rcat
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10985/68042011-01-01T00:00:00ZMERCKEL, YannickDIANI, JulieBRIEU, MathiasGILORMINI, PierreCAILLARD, JulienSeveral carbon-black filled styrene-butadiene rubbers showed different sensibilities to the Mullins softening when submitted to cyclic uniaxial tension. In order to quantify this softening, a damage parameter was introduced. It is defined by using a classic damage approach and can be estimated by using either the strain amplification factor method or the tangent modulus at zero stress. The proposed parameter is used to study the effects of crosslink density and filler amount on the Mullins softening. The latter is shown to remain unaffected by a change of crosslink density and to increase with an increase of filler amount. The damage parameter exhibits mere linear dependences on the maximum Hencky strain applied and on the filler volume fraction. A simple linear expression is given finally to predict the Mullins softening of filled rubbers. The parameter also provides an objective analysis for the Mullins softening that supports comments on a better understanding of this effect.Testing some implementations of a cohesive-zone model at finite strain
http://hdl.handle.net/10985/10171
Testing some implementations of a cohesive-zone model at finite strain
GILORMINI, Pierre; DIANI, Julie
This study shows how the results given by a cohesive-zone model at finite strain may depend strongly on its numerical implementation. A two-dimensional four-node cohesive element is considered, which includes several variants depending on a part of the strain-displacement matrix, on the quadrature rule applied, and on the configuration chosen to perform integration. Finite element simulations combine these variants with a very simple, bilinear, cohesive-zone model, in two tests. The first test involves a single element and illustrates some features of the various implementations. The other test simulates the peeling of an elastomer strip from a rigid substrate.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/101712015-01-01T00:00:00ZGILORMINI, PierreDIANI, JulieThis study shows how the results given by a cohesive-zone model at finite strain may depend strongly on its numerical implementation. A two-dimensional four-node cohesive element is considered, which includes several variants depending on a part of the strain-displacement matrix, on the quadrature rule applied, and on the configuration chosen to perform integration. Finite element simulations combine these variants with a very simple, bilinear, cohesive-zone model, in two tests. The first test involves a single element and illustrates some features of the various implementations. The other test simulates the peeling of an elastomer strip from a rigid substrate.Cyclic and monotonic testing of free and constrained recovery properties of a chemically crosslinked acrylate
http://hdl.handle.net/10985/7759
Cyclic and monotonic testing of free and constrained recovery properties of a chemically crosslinked acrylate
ARRIETA, Juan Sebastian; DIANI, Julie; GILORMINI, Pierre
A chemically crosslinked acrylate network was submitted to various thermomechanical strain and stress recoveries while changing the experimental parameters in order to better define the benefits and the limits of using chemically crosslinked polymers for multicycle applications or applications under external constraints. The results showed that the free recoveries and the constrained recoveries remained the same at the first cycle and during the next ones. It was also shown that the low stress usually generated by a crosslinked network when submitted to a constrained recovery can be significantly increased by choosing suitable experimental conditions.
The definitive version is available at http://onlinelibrary.wiley.com/doi/10.1002/app.39813/full
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/77592014-01-01T00:00:00ZARRIETA, Juan SebastianDIANI, JulieGILORMINI, PierreA chemically crosslinked acrylate network was submitted to various thermomechanical strain and stress recoveries while changing the experimental parameters in order to better define the benefits and the limits of using chemically crosslinked polymers for multicycle applications or applications under external constraints. The results showed that the free recoveries and the constrained recoveries remained the same at the first cycle and during the next ones. It was also shown that the low stress usually generated by a crosslinked network when submitted to a constrained recovery can be significantly increased by choosing suitable experimental conditions.Crosslink Density Changes during the Hydrolysis of Tridimensional Polyesters
http://hdl.handle.net/10985/8276
Crosslink Density Changes during the Hydrolysis of Tridimensional Polyesters
RICHAUD, Emmanuel; GILORMINI, Pierre; COQUILLAT, Marie; VERDU, Jacques
The hydrolysis of almost ideal networks based on macrodiols of average molar mass about 2 kg mol 1, with L¼18 ester groups per chain is studied. Tensile testing is used to evaluate the crosslink density through the statistical theory of rubber elasticity at two temperatures and three values of relative humidity. A kinetic model for ester consumption including an autocatalysis term is proposed and combined with two original approaches for modeling the crosslink density changes. This allows kinetic parameters of hydrolysis to be determined, and very good predictions are obtained for the variations of crosslink density (or elastic modulus) in the three aging conditions considered. The initial curvature of elastic modulus versus time is predicted positive for weak autocatalysis and negative for strong autocatalysis. The obtained conversion ratio at degelation is found to decrease sharply with the number of esters per elastically active chain
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/82762014-01-01T00:00:00ZRICHAUD, EmmanuelGILORMINI, PierreCOQUILLAT, MarieVERDU, JacquesThe hydrolysis of almost ideal networks based on macrodiols of average molar mass about 2 kg mol 1, with L¼18 ester groups per chain is studied. Tensile testing is used to evaluate the crosslink density through the statistical theory of rubber elasticity at two temperatures and three values of relative humidity. A kinetic model for ester consumption including an autocatalysis term is proposed and combined with two original approaches for modeling the crosslink density changes. This allows kinetic parameters of hydrolysis to be determined, and very good predictions are obtained for the variations of crosslink density (or elastic modulus) in the three aging conditions considered. The initial curvature of elastic modulus versus time is predicted positive for weak autocatalysis and negative for strong autocatalysis. The obtained conversion ratio at degelation is found to decrease sharply with the number of esters per elastically active chainOn using the leveling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length
http://hdl.handle.net/10985/7394
On using the leveling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length
GILORMINI, Pierre; TEYSSEDRE, Hubert
Measuring the relaxation time involved in the leveling of the free surface of a Newtonian fluid laid on a substrate can give access to material parameters. It is shown here how most favorable pattern geometries of the free surface and film thicknesses can be defined for the measures of viscosity and Navier slip length at the fluid-solid interface, respectively. Moreover, special emphasis is put on the conditions required to avoid shear-thinning by controling the maximum shear rate. For initially sinusoidal patterns with infinitesimal amplitudes, an analytical solution including slip at the fluid-solid interface is used, and numerical simulations based on the natural element method allow to discuss the effect of finite amplitudes. This leads to the definition of a relevance domain for the analytical solution that avoids the need for numerical simulations in practical applications. It is also shown how these results can be applied to crenelated profiles, where Fourier series expansion can be used, but with caution.
Version éditeur : http://rspa.royalsocietypublishing.org/content/469/2160/20130457.short
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/73942013-01-01T00:00:00ZGILORMINI, PierreTEYSSEDRE, HubertMeasuring the relaxation time involved in the leveling of the free surface of a Newtonian fluid laid on a substrate can give access to material parameters. It is shown here how most favorable pattern geometries of the free surface and film thicknesses can be defined for the measures of viscosity and Navier slip length at the fluid-solid interface, respectively. Moreover, special emphasis is put on the conditions required to avoid shear-thinning by controling the maximum shear rate. For initially sinusoidal patterns with infinitesimal amplitudes, an analytical solution including slip at the fluid-solid interface is used, and numerical simulations based on the natural element method allow to discuss the effect of finite amplitudes. This leads to the definition of a relevance domain for the analytical solution that avoids the need for numerical simulations in practical applications. It is also shown how these results can be applied to crenelated profiles, where Fourier series expansion can be used, but with caution.Thermoforming of a PMMA transparency near glass transition temperature
http://hdl.handle.net/10985/6684
Thermoforming of a PMMA transparency near glass transition temperature
GILORMINI, Pierre; CHEVALIER, Luc; REGNIER, Gilles
In order to simulate the thermoforming of a transparency, constitutive equations are proposed for the nonlinear viscoelastic behaviour of poly(methyl methacrylate) near glass transition temperature, which include large deformations. In a first step, they are fitted on a set of uniaxial tensionrelaxation tests at various strain levels and strain rates. In a second step, their implementation in a finite element code is performed. Finally, the thermoforming of a transparency at a constant and uniform temperature is simulated and compared with experimental results.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10985/66842010-01-01T00:00:00ZGILORMINI, PierreCHEVALIER, LucREGNIER, GillesIn order to simulate the thermoforming of a transparency, constitutive equations are proposed for the nonlinear viscoelastic behaviour of poly(methyl methacrylate) near glass transition temperature, which include large deformations. In a first step, they are fitted on a set of uniaxial tensionrelaxation tests at various strain levels and strain rates. In a second step, their implementation in a finite element code is performed. Finally, the thermoforming of a transparency at a constant and uniform temperature is simulated and compared with experimental results.Micromechanical modeling of the linear viscoelasticity of carbon-black filled styrene butadiene rubbers: the role of the rubber-filler interphase
http://hdl.handle.net/10985/6830
Micromechanical modeling of the linear viscoelasticity of carbon-black filled styrene butadiene rubbers: the role of the rubber-filler interphase
DIANI, Julie; GILORMINI, Pierre; MERCKEL, Yannick; VION-LOISEL, Fabien
Micromechanics modeling of the linear viscoelasticity of carbon-black filled styrene butadiene rubbers (SBR) shows that a simple representation of a spherical rigid-phase surrounded by rubber gum and embedded in an homogeneous equivalent medium provides access to the effective volume fraction of fillers. This simple representation is successful for a significant range of filler amount, and for materials in the glassy state. For materials in the rubbery state, experimental results support the existence of a filler-rubber interphase with reduced mobility due to confinement. The 4-phase micromechanics model, which accounts for a bounded rubber layer coating the fillers, provides satisfactory estimates of the linear viscoelasticity of filled rubbers from the rubbery state to the glassy state. It also provides access to the filler rubber interphase behavior that appears viscoelastic, and to an estimate of the interphase thickness.
Version éditeur : http://www.sciencedirect.com/science/article/pii/S0167663612002190
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/68302013-01-01T00:00:00ZDIANI, JulieGILORMINI, PierreMERCKEL, YannickVION-LOISEL, FabienMicromechanics modeling of the linear viscoelasticity of carbon-black filled styrene butadiene rubbers (SBR) shows that a simple representation of a spherical rigid-phase surrounded by rubber gum and embedded in an homogeneous equivalent medium provides access to the effective volume fraction of fillers. This simple representation is successful for a significant range of filler amount, and for materials in the glassy state. For materials in the rubbery state, experimental results support the existence of a filler-rubber interphase with reduced mobility due to confinement. The 4-phase micromechanics model, which accounts for a bounded rubber layer coating the fillers, provides satisfactory estimates of the linear viscoelasticity of filled rubbers from the rubbery state to the glassy state. It also provides access to the filler rubber interphase behavior that appears viscoelastic, and to an estimate of the interphase thickness.