Solvent release from highly swollen gels under compression: an important phenomenon that has to be taken into account

National audienceThe behavior of a strongly charged polyelectrolyte gel under a uniaxial compression was studied, demonstrating the evidence of gel deformation and volume loss at the same time. A theoretical approach shows that solvent release takes place for both weakly charged and neutral gels, being more pronounced for polyelectrolyte hydrogels = Nous avons étudié le comportement de gels fortement polyélectrolytiques sous compression uniaxiale. Il est observé que le gel se déforme et expulse de son solvant en même temps. Une analyse théorique prédit cette perte de solvant pour des gels faiblement chargés comme pour des gels neutres. Le phénomène est plus prononcé pour le cas du gel polyélectrolytique

A Light Scattering Theory for Filled Diluted Polymer Solution under Flow

Light scattering by dilute flexible polymer solutions filled with spherical particles is studied theoretically within the framework of the Rayleigh-Gans-Debye approximation. The basic idea of our work is that the perturbation of stream lines and flow rates due to the presence of the particles will change the local conformation of the chains, thus inducing a light scattering contribution. This treated by considering viscosity fluctuations. The Rayleigh ratio is derived as a function of the viscosity fluctuation correlation function for the four major polarization configurations (HH, VV, HV and VH) in shear and elongational flow. Considering a random distribution of the particles, the small angle light scattering patterns are calculated.La diffusion de lumière par des solutions de polymères flexibles chargées de particules sphériques est étudiée grâce à l'approximation théorique de Rayleigh-Gans-Debye. L'idée de base du travail est que les perturbations des lignes de courant et des taux d'écoulement dues à la présence des particules vont changer la conformation locale des chaines, entrainant une diffusion de la lumière. Traitant ces perturbations comme des fluctuations de viscosité, le rapport de Rayleigh est calculé en tenant compte de la fonction de corrélation des fluctuations de viscosité pour les quatres orientations principales des polariseurs, HH, VV, HV et VH, et pour des écoulements de cisaillement et d'élongation. Les clichés de diffusion de lumière sont calculés en considérant une distribution aléatoire de particules

The EUROMECH Colloquium 487 "Structure sensitive mechanics of polymer materials: physical and mechanical aspects

International audienc

International colloquium "structure-sensitive mechanics of polymer materials: physical and mechanical aspects"

International audienc

Stress-strain behavior of high-density polyethylene below the yield point: Effect of unloading rate

International audienc

Numerical modeling of deformation behaviour of semi crystaline polymers

International audienc

Coupling of Nanocavitation With Cyclic Deformation Behavior of High-Density Polyethylene Below the Yield Point

The peculiarities of viscoelastic behavior of high-density polyethylene (HDPE) subjected to the uniaxial cyclic tensions and retractions below the yield point are studied. This required using three different deformation programs including (i) the successive increase in strain maximum of each cycle, (ii) the controlled upper and lower stress boundaries, and (iii) the fixed strain at the backtracking points. The experimental data are analyzed in a framework of the modified structure-sensitive mode