yves béreaux - Academia.edu (original) (raw)

Papers by yves béreaux

Nucleation and Atmospheric Aerosols, 2018

Single-screw plastication, used in extrusion and in injection moulding, is a major way of process... more Single-screw plastication, used in extrusion and in injection moulding, is a major way of processing commodity thermoplastics. During the plastication phase, the polymeric material is melted by the combined effects of shear-induced self-heating (viscous dissipation) and heat conduction coming from the barrel. In injection moulding, a high level of reliability is usually achieved that makes this process ideally suited to mass market production. Nonetheless, process fluctuations still appear that make moulded part quality control an everyday issue. In this work, we used a combined modelling of plastication, throughput calculation and laminar dispersion, to investigate if, and how, thermal fluctuations could propagate along the screw length and affect the melt homogeneity at the end of the metering section. To do this, we used plastication models to relate changes in processing parameters to changes in the plastication length. Moreover, a simple model of throughput calculation is used to relate the screw geo...

HAL (Le Centre pour la Communication Scientifique Directe), Apr 18, 2007

To be able to predict the throughput of a single‐screw extruder or the metering time of an inject... more To be able to predict the throughput of a single‐screw extruder or the metering time of an injection moulding machine for a given screw geometry, set of processing conditions and polymeric material is important both for practical and designing purposes. Our simple model show that the screw geometry is the most important parameter, followed by polymer rheology and processing conditions. Melting properties and length seem to intervene to a lesser extent. The calculations hinges on the idea of viewing the entire screw as a pump, conveying a solid and a molten fraction. The evolution of the solid fraction is the essence of the plastication process, but under particular circumstances, its influence on the throughput is nil. This allows us to get a very good estimate on the throughput and pressure development along the screw. Our calculations are compared to different sets of experiments available from the literature. We have consistent agreement both in throughput and pressure with published data.

Packaging Technology and Science, Nov 24, 2022

An innovative process for packaging films sealing has been recently promoted: Heat is provided on... more An innovative process for packaging films sealing has been recently promoted: Heat is provided on the upper side of the polymer films. In this paper, sealing conditions are studied for two PET‐PE films. Melting temperature of the sealant layer material was determined by differential scanning calorimetry (DSC), through both conventional and successive self nucleation and annealing procedures. Interface temperature was measured during sealing, and a temperature model was fitted to compute the effective sealing time for each process parameter. Unconventional T‐peel tests were established with disk‐shaped seal samples. Strengths of the seals formed for different process parameters were measured. Results have shown that the melting temperature measured by DSC (108° C and 99° C for PE70 and PE120, respectively) is the seal initiation temperature of the materials. Results of T‐peel tests can be divided in two regions: A growth region where seal strength values increase, up to a threshold at which the seal strength is almost constant (20 N/10 mm). In the growth region, we propose a time–temperature relationship between seal strength, tool temperature, and effective sealing time in the form of an Arrhenius model . The value of the time exponent in the model is in agreement with what the chain diffusion theory predicted .

International Polymer Processing, Aug 12, 2016

Thanks to the single stage injection blow molding process, specific hollow parts can be produced ... more Thanks to the single stage injection blow molding process, specific hollow parts can be produced with standard injection molding machine. A specific mold is designed, enabling the preform injection molding, as well as its blow molding on the same machine. The preform is blow molded right after its injection molding. This particular process does not involve preform storage and reheating before the blow molding stage. This implies that the preform has to remain sufficiently malleable to be blown while being viscous enough to avoid being pierced during the blow molding stage. The polymer used is a polypropylene random copolymer. Therefore the process takes place between the melting temperature and the crystallization one. As the preform is blow molded right after being injected, this single stage process involves high temperature before the blowing. The polymer rheological behavior is investigated through dynamic rheometry in its molten state at various temperatures. A viscous Cross model is used with the thermal dependence assumed by an Arrhenius law. The process is simulated through a finite element code (Polyflow) in the ANSYS Workbench framework. The geometry allows an axisymmetric approach. The transient simulation is run under anisothermal conditions and viscous heating is taken into account. Two geometries are simulated. First, the flask geometry has been used to show the process efficiency. The yoghurt pot geometry has been designed later for industrial application in a more sophisticated mold than the flask mold. Blow molded parts are analyzed by tomography and the thickness has been measured by the tomography data image analysis. The simulation results are compared to the experimental ones. The simulation fits well with the experimental results concerning both geometries. The simple numerical model proposed proves to be robust enough to predict well the blow molded parts final thickness repartitions provided that the relevant temperature and pressure conditions are well defined.

ESAFORM 2021, Apr 10, 2021

In this paper, we present an innovative welding process for packaging applications developed by S... more In this paper, we present an innovative welding process for packaging applications developed by SEALESTER Company. For polymer films, studies have revealed that the welding interface must reach a specific temperature, known as "sealing initiation temperature", to obtain a sealed joint. In this paper, we will be studying the effect of the process parameters on the evolution of temperature at the welding interface. For this purpose, thermocouples have been placed between the films at different points of the trajectory to measure the temperature evolution. Process parameters and temperature measurements were recorded in each experiment. Results show that the most influential parameters are the temperature and the linear velocity of the tool. Rotational frequency affects the heat distribution on the sealing surface. A minimum pressure must be applied. In conclusion, this new process can produce sealed polymer packages. Future work will consist of studying the quality of obtained seal in addition to optimization and control of the process.

International Journal of Thermal Sciences, Dec 1, 2019

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial| 4.0 International License

Journal of Rheology, Mar 1, 2014

ABSTRACT The aim of this study is to develop an experimental method which provides relevant data ... more ABSTRACT The aim of this study is to develop an experimental method which provides relevant data about the rheological behavior of polymer melts in pressure-driven flows in microscale geometries. In order to get better description of the physics involved in such flows, numerical simulation with commercial and in-house softwares was implemented, especially with molecular dynamics constitutive models. Thus, a modular rheometrical slit die equipped with pressure and temperature transducers was designed and adapted to a capillary rheometer. Different gap dimensions between 50 mu m and 200 mu m are available. The measurements were performed with high density polyethylene and low density polyethylene. The device was assessed by comparing to usual rheometers. The wall slip was investigated according to Mooney's method. Simulations were conducted with MATLAB (R) by implementing the Doi-Edwards' tube model and the molecular stress function of Wagner to take into account the enhanced orientation of the molecules due to the very close vicinity of the die walls. The flow was also simulated with POLYFLOW (R). The pressure effect on the geometry and on the polymer material was investigated. Experimental results were compared to calculations in terms of pressure values. The conclusions somewhat modify the prospects for future studies of such flows. (C) 2014 The Society of Rheology.

HAL (Le Centre pour la Communication Scientifique Directe), May 8, 2019

HAL (Le Centre pour la Communication Scientifique Directe), Dec 1, 2002

A Computational Fluid Dynamics analysis of the flow through the distributionplate of a fibre spin... more A Computational Fluid Dynamics analysis of the flow through the distributionplate of a fibre spinning pack has been performed. The features of the flow that are relevant to polymer processing are addressed, such as the wall shear rate, residence time and dead zones. An analyticalmodel, that agrees very well with the calculations, is proposed. It also yields insight into the role played in the flow by different design parameters of the distribution plate. This model, primarily based upon a Newtonian fluid, is also extended to a shear thinning one.

HAL (Le Centre pour la Communication Scientifique Directe), Jun 3, 2019

International audienc

HAL (Le Centre pour la Communication Scientifique Directe), Oct 15, 2019

International audienc

Journal of Non-newtonian Fluid Mechanics, Dec 1, 2017

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights • Lubrication solution for viscoelastic flows in 2D slowly varying channels • Viscoelastic stress profiles are very different in convergent flows from divergent flows • Viscoelastic effects appear as higher-order terms in the perturbation expansion • Padée approximants can extend the range of Weissenberg numbers for which the perturbation solution is valid

International Journal of Material Forming, Apr 1, 2008

AIP Conference Proceedings, 2019

Single-screw plastication, used in extrusion and in injection moulding, is a major way of process... more Single-screw plastication, used in extrusion and in injection moulding, is a major way of processing commodity thermoplastics. In injection moulding, a high level of reliability is usually achieved that makes this process ideally suited to mass market production. Nonetheless, process fluctuations still appear that make moulded part quality control an everyday issue. During the plastication phase, prior to the injection phase, the polymeric material is melted by the combined effects of shear-induced self heating (viscous dissipation) and heat conduction coming from the barrel. A combined drag and pressure difference flow is imparted on the molten polymer along the screw channel. The low thermal diffusion coefficient of molten polymers implies that convection is dominant over diffusion and leads to very large Peclet numbers. However, the screw channel length is large enough for the flow to present significant diffusion effects. Therefore, the objective of this work is to study the capacity of this particular class of flows to dampen any transient inlet temperature disturbances occurring at the beginning of the metering zone of the screw channel. The integral transform method is applied to the transient energy conservation equation with the laminar velocity profile obtained for drag and pressure difference flow of a Newtonian fluid. We found that the knowledge of a single eigenvalue is sufficient to characterise the dampening efficiency of a flow and that a higher level of back-pressure is indeed improving the thermal homogeneity in the flow.

Les Cahiers De Rheologie, 2000

Nous nous interessons a l'ecoulement et au transfert thermique d'un polymere fondu dans u... more Nous nous interessons a l'ecoulement et au transfert thermique d'un polymere fondu dans une buse durant la phase d'injection. Nous utilisons le logiciel POLYFLOW pour simuler l'ecoulement du fluide Non-Newtonien modelise par une loi de Bird-Carreau et par une loi viscoelastique de Giesekus. Le couplage thermo-mecanique est pris en compte a deux niveaux : d'une part, par la dissipation visqueuse dans l'equation d'energie, d'autre part, par la thermodependance des parametres materiels (temps de relaxation et viscosite). Le contact thermique entre la paroi d'acier et le polymere fondu fait l'objet d'un calcul convection-conduction. Nous constatons que le regimes thermique et mecanique developpes sont inaccessibles et que la paroi est quasi-adiabatique.

Nucleation and Atmospheric Aerosols, 2018

Single-screw plastication, used in extrusion and in injection moulding, is a major way of process... more Single-screw plastication, used in extrusion and in injection moulding, is a major way of processing commodity thermoplastics. During the plastication phase, the polymeric material is melted by the combined effects of shear-induced self-heating (viscous dissipation) and heat conduction coming from the barrel. In injection moulding, a high level of reliability is usually achieved that makes this process ideally suited to mass market production. Nonetheless, process fluctuations still appear that make moulded part quality control an everyday issue. In this work, we used a combined modelling of plastication, throughput calculation and laminar dispersion, to investigate if, and how, thermal fluctuations could propagate along the screw length and affect the melt homogeneity at the end of the metering section. To do this, we used plastication models to relate changes in processing parameters to changes in the plastication length. Moreover, a simple model of throughput calculation is used to relate the screw geo...

HAL (Le Centre pour la Communication Scientifique Directe), Apr 18, 2007

Packaging Technology and Science, Nov 24, 2022

International Polymer Processing, Aug 12, 2016

ESAFORM 2021, Apr 10, 2021

International Journal of Thermal Sciences, Dec 1, 2019

Journal of Rheology, Mar 1, 2014

HAL (Le Centre pour la Communication Scientifique Directe), May 8, 2019

HAL (Le Centre pour la Communication Scientifique Directe), Dec 1, 2002

HAL (Le Centre pour la Communication Scientifique Directe), Jun 3, 2019

International audienc

HAL (Le Centre pour la Communication Scientifique Directe), Oct 15, 2019

International audienc

Journal of Non-newtonian Fluid Mechanics, Dec 1, 2017

International Journal of Material Forming, Apr 1, 2008

AIP Conference Proceedings, 2019

Single-screw plastication, used in extrusion and in injection moulding, is a major way of process... more Single-screw plastication, used in extrusion and in injection moulding, is a major way of processing commodity thermoplastics. In injection moulding, a high level of reliability is usually achieved that makes this process ideally suited to mass market production. Nonetheless, process fluctuations still appear that make moulded part quality control an everyday issue. During the plastication phase, prior to the injection phase, the polymeric material is melted by the combined effects of shear-induced self heating (viscous dissipation) and heat conduction coming from the barrel. A combined drag and pressure difference flow is imparted on the molten polymer along the screw channel. The low thermal diffusion coefficient of molten polymers implies that convection is dominant over diffusion and leads to very large Peclet numbers. However, the screw channel length is large enough for the flow to present significant diffusion effects. Therefore, the objective of this work is to study the capacity of this particular class of flows to dampen any transient inlet temperature disturbances occurring at the beginning of the metering zone of the screw channel. The integral transform method is applied to the transient energy conservation equation with the laminar velocity profile obtained for drag and pressure difference flow of a Newtonian fluid. We found that the knowledge of a single eigenvalue is sufficient to characterise the dampening efficiency of a flow and that a higher level of back-pressure is indeed improving the thermal homogeneity in the flow.

Les Cahiers De Rheologie, 2000